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Answer and explain 4 discussion questions related to strength and nutrition. The answer should be around 2-3 pages long

1) A strength/power athlete who is trying to gain a small amount of weight, primarily as
muscle mass, should consume approximately:
â€¢
____________ calories per day more than current calorie intake
â€¢
____________ grams of carbohydrate per kg of body weight
â€¢
____________ grams of protein power per kg body weight
â€¢
____________ percent of total calorie intake as fat
Provide a justification for your answers to each of the entries above.
2) List at least 5 ways coaches, trainers, and dieticians can help team members stay wellhydrated during outdoor practices in hot and humid conditions.
3) Case: Susan is a 15-year-old middle distance track and cross-country runner on her high
school team. She was diagnosed with Type 1 diabetes 3 months ago during the off
season. Now the cross-country season has started, and she plans to train and compete just
as hard as last year, prior to her diabetes diagnosis.
Questions:
glucose and ketone levels as well as recommendations for exercise based upon those levels.
2. You are the dietician or athletic trainer for Susan’s cross-country team. You are aware of
her recent diabetes diagnosis, and she has shared with you her medications and current
dietary regimen. Describe your role in helping Susan optimize her performance by training
and competing safely. How do you prepare for the possibility of a diabetic emergency on
the course?
4) Case: Jake is a collegiate soccer player. His team has just completed a very successful
season. They are moving into their offseason, during which their workouts are unstructured
to allow for rest and recovery. Jake is interested in continuing to stay in shape and to eat
healthfully. He has made an appointment with you to determine how he should modify his
diet based on his change in workouts.
Questions:
1. Assuming Jake is 20 years old and weights 165 pounds, calculate his daily calorie, protein,
carbohydrate, and fat requirements for the offseason.
CHAPTER 13
Strength/Power Athletes
1. What is different about strength/power athletes?
2. What energy systems are utilized during
strength/power exercise?
3. Are the calorie needs of strength/power athletes
different from those of other types of athletes?
4. Are carbohydrate needs different for
strength/power athletes?
5. Are protein needs different for strength/power
athletes?
6. Are fat needs different for strength/power athletes?
7. Are vitamin and mineral needs different for
strength/power athletes?
8. Are fluid needs different for strength/power
athletes?
9. What meal-planning/event logistics need to be
considered during strength/power events?
You Are the Nutrition Coach
Robert is a 45-year-old competitive masters power lifter who
competes in the 181-pound weight class. He has been having
trouble keeping his body weight low enough to compete in the
181-pound class and is concerned that his body fat level is
actually increasing despite his heavy weight-training regimen.
He has a rather sedentary office job and tries to walk about a
mile every weekday evening with his wife. He states that he
eats well (approximately 3,500 calories per day). To help build
muscle and enhance recovery, he consumes about 250
grams of protein per day from natural food sources and
supplementation. He has decreased his carbohydrate intake
because he has been experimenting with a low-carbohydrate
diet to control his weight.
Question
Why is Robert having trouble controlling his body weight?
What are the most glaring concerns about his diet?
strength/power athletes?
The terms strength and power are often used
interchangeably when describing athletes. Although
strength and power are important aspects of physical
fitness, and strength is a component of power, they
are not synonymous. Strength is the ability of a
muscle or group of muscles to generate force.
Strength is purely a measure of how much weight
can be moved or lifted by an athlete. It is highly
dependent on the amount of muscle tissue an athlete
possesses. In other words, the bigger the muscle,
the greater the strength. Power, in contrast, is
dependent not only on how much force can be
developed by the muscles (i.e., strength) but also on
how fast the force can be generated. Because
velocity of movement is an integral part of power,
power is often referred to as speed-strength. The
ability to run, jump, throw, and quickly change
direction are all very dependent upon the ability of
muscle to rapidly generate force (i.e., power). For the
purposes of this chapter, strength/power athletes are
those involved in the explosive track and field events
(i.e., javelin, shot put, discus, high jump, long jump,
hammer, sprints), weight lifting, gymnastics, and
wrestling, just to name a few. In short,
strength/power athletes are athletes who participate
in sports in which success is dependent primarily on
the demonstration of brute strength, or relatively
short bursts (i.e., â‰¤1.5 minutes) of near-maximal,
muscle-force production.
The pure strength/power athletes are different
from many other athletes in that success in their
sport relies on activities of short duration; for
example, any of the throws in track and field take
only a few seconds to perform. As a result, the
energy needs and goals of training differ vastly from
those of the endurance athlete. This chapter
discusses the macro- and micronutrient needs of
strength/power athletes along with issues regarding
hydration and meal planning.
What energy systems are utilized
during strength/power exercise?
The bodyâ€™s three energy systems (the phosphagen,
anaerobic, and aerobic systems) are constantly working
together to meet the bodyâ€™s immediate energy demands. The
short, high-intensity muscle contractions required to perform
strength and power sports rely heavily on the phosphagen
system with increasing contribution from the anaerobic
system as the length of the activity increases (see FIGURE
13.1 ). In the case of a strength athlete performing a onerepetition maximum bench press, the actual time the athlete
spends performing the lift may be only 4 seconds. The time
interval is even shorter for a javelin thrower or a person
performing the shot put (i.e., the left-most region of area 1 in
Figure 13.1). Muscle stores of adenosine triphosphate (ATP)
and creatine phosphate (CP) enable the muscles of these
athletes to meet the immediate demands for energy and thus
complete a successful lift or throw. On the other end of the
strength/power spectrum is an athlete such as an 800-meter
sprinter. These athletes derive the majority of their energy
from the combined efforts of the phosphagen and anaerobic
energy systems (i.e., right-most region of area 2 in Figure
13.1).
Figure 13.1 Strength/power athletes rely primarily on the phosphagen
and anaerobic energy systems to provide ATP. Shaded area 1 in the graph
represents all-out activities that progress in length from 1 second (left
margin) to 30 seconds (right margin). Area 2 involves all-out efforts that
progress from 30 seconds to about 1.5 minutes. Strength/power athletes
tend to perform activities that fall in areas 1 and 2. Although the aerobic
energy system is not a major provider of energy for these athletes, it is
important for recovery afterward.
Reproduced from McGraw-Hill Education from Bowers RW, Fox EL. Sports
Physiology, 3rd ed. Dubuque, IA: William C Brown Publishers; 1992, p. 34.
Depending upon the nature of the sport, it may be
necessary to repeat the strength/power movement numerous
times. Even though the phosphagen and the anaerobic
systems supply the immediate energy need, the aerobic
system should not be neglected or shrugged off as
unimportant. In the case of a shot putter, aerobic metabolism
is relatively unimportant because there is usually plenty of rest
time between puts to recover; however, other strength/power
sports require the athlete to repeatedly perform
strength/power movements over a period of time with
relatively short intervals of rest. In these cases, the aerobic
system is important for supplying the energy for recovery,
which, in turn, indirectly affects performance by delaying the
onset of fatigue. An example of a sport requiring repeated,
powerful bursts of muscle activity can be seen during
gymnastics competitions. In competition and during training,
skills requiring muscle strength and power are separated by
short rest periods that occur during the event (e.g., between
tumbling runs during floor exercise) or between apparatus as
the athletes rotate from one to another. Muscle recovery and
the associated recharging of the creatine and ATP stores are
dependent upon the aerobic system. Therefore, if
strength/power athletes neglect the development of their
aerobic system, their ability to recover will be impaired, and
fatigue will ensue more quickly.
In summary, strength/power athletes rely primarily on the
phosphagen energy system to provide ATP during
strength/power events, with increasing contributions of ATP
coming from the anaerobic energy system as the duration of
the activity increases. Although the aerobic energy system
contributes little ATP during the actual strength/power activity,
it is important for recovery after the activity. During the
recovery period, the aerobic energy system replenishes ATP
and CP levels, thus recharging the phosphagen system and
delaying the onset of fatigue.
Are the calorie needs of
strength/power athletes different
from those of other types of
athletes?
As with most athletes, the main dietary concern with individuals
involved in strength/power sports is the consumption of adequate
amounts of total daily calories. Energy needs are based on several
factors, including age, gender, body mass, and sport-specific
demands, which can vary tremendously among athletes. No single
macronutrient is more important than the others; thus the dietary
composition for strength/power athletes is not much different from
the recommended healthy diet of nonathletes. This section will
review calculating total calorie needs for strength/power athletes,
and subsequent sections will focus on the roles of each of the
macronutrients, micronutrients, and fluids.
How are daily calorie needs calculated for
strength/power athletes?
For strength/power athletes, similar to other athletes, there are three
main considerations when determining energy needs and
developing an individualized meal plan: Does the athlete want to
maintain, lose, or gain weight? In the category of strength/power
athletes, weight goals span an enormous continuum. On one end of
the spectrum are weight lifters who, in general, are trying to gain
muscle tissue and build mass. On the other end are gymnasts who,
in general, are attempting to minimize body mass while
simultaneously aiming for increased strength and power. Therefore,
nutrition plans need to meet the athleteâ€™s basic nutrient requirements
while also reflecting the athleteâ€™s desires and goals.
The energy needs for strength/power athletes can be calculated
using the equations and activity factors presented in TABLE 13.1 .
The following examples provide real-life scenarios of strength/power
athletes who want to lose, maintain, or gain weight. Each scenario
reviews how to calculate energy needs and provides
recommendations based on the athleteâ€™s goals and objectives.
Table 13.1
Resting Energy Expenditure (REE) Calculations and Activity
Factors
Gender and age
Equation(BW in
kilograms)
Activity
factor
Males, 10 to 18 years REE = (17.5 Ã— BW) + 651 1.6â€“2.4
Males, 18 to 30 years REE = (15.3 Ã— BW) + 679 1.6â€“2.4
Males, 30 to 60 years REE = (11.6 Ã— BW) + 879 1.6â€“2.4
Females, 10 to 18
years
REE = (12.2 Ã— BW) + 749 1.6â€“2.4
Females, 18 to 30
years
REE = (14.7 Ã— BW) + 496 1.6â€“2.4
Females, 30 to 60
years
REE = (8.7 Ã— BW) + 829
1.6â€“2.4
Data from World Health Organization. Energy and Protein Requirements.
Report of a Joint FAO/WHO/UNU Expert Consultation. Technical Report 724.
Geneva, Switzerland: World Health Organization;1985:206.
How can calorie needs be calculated for athletes
aiming to lose/minimize body weight while
increasing strength/power?
Female gymnasts are a category of strength/power athletes who are
generally aiming to lose weight or maintain an already low weight. To
obtain their goal, many gymnasts are eating suboptimal levels of not
only total calories but also a variety of nutrients. Several studies
have examined the differential between recommended and actual
calorie intake. The results are staggeringâ€”gymnasts are consuming
only 47 to 84% of their daily calorie requirements!1â€“4 When working
with female gymnasts or any other strength/power athlete whose
goal is to lose weight, calculate energy needs and then compare the
calculations to actual current intake before developing a meal plan
and making recommendations.
Lyndsiâ€™s Case Study
Kari, the mother of an 11-year-old gymnast named Lyndsi
calls to make an appointment with a sports nutritionist. Kari has
grown increasingly concerned about her daughterâ€™s eating habits
and weight loss over the past several months. Lyndsi has been
part of a local club team for several years that practices 2 to 3
hours a day, 5 to 6 days a week. While on summer break, the
club team hosted a 2-week gymnastic camp. Lyndsi was very
excited about the opportunity to train and learn from the older
girls on the team, commenting to her mother several times about
how she envied their performance and abilities. At the end of
camp, Kari noticed gradual changes in her daughterâ€™s eating
habitsâ€”Lyndsi began to turn down her favorite foods, and she
had developed a strong aversion to any food containing fat.
Lyndsiâ€™s eating habits subsequently became very routine,
consisting of a plain bagel for breakfast, an iceberg lettuce and
green pepper salad with nonfat dressing for lunch, and a chicken
breast, baked potato, and broccoli every night for dinner (see
TRAINING TABLE 13.1 ). Lyndsi would usually have a small
bowl of nonfat frozen yogurt or dry cereal for a snack in the
evening. Kari has noticed a â€œdrawnâ€ look to Lyndsiâ€™s face and that
her clothes seemed to just hang loosely on her body. The point at
which she knew it was time to seek professional assistance was
when Lyndsi went to the doctor for a routine checkup, and her 5â€™
3â€ frame weighed only 95 pounds. She is certain Lyndsi is not
eating enough but is unsure of how much she should be
consuming and how she can get Lyndsi back on track to â€œnormalâ€
eating.
Training Table 13:1 Lyndsiâ€™s Initial and
Revised Meal Plans
Making recommendations. In this situation, Lyndsi has made
some drastic changes to her diet and, as a result, noticeable
weight loss has occurred.
1. The first step is to estimate her total calorie needs:
REE = (12.2 Ã— BW in kg) + 749 = (12.2 Ã— 43.2) + 749 = 1,276
Total calorie needs = REE Ã— Activity factor = 1,276 Ã— (1.6 â€“ 2.4) =
2,041â€“3,062 calories/day
Lyndsi needs at least 2,041 calories per day on rest or
easy days, and up to 3,062 calories a day for heavy
training days (3+ hours per day).
2. The second step is to estimate her calorie intake. Refer to
Training Table 13.1 for Lyndsiâ€™s initial meal plan. After
making changes to her diet, she was only consuming ~900
calories a day. It is obvious that she is not meeting her
energy requirementsâ€”in fact, she is only consuming 45%
of her bottom-level energy needs ([916 calories/2,041
calories] Ã— 100 = 45%). One of the roles of a sports
nutrition professional is to understand the clientâ€™s
perspective by determining why a client eats in a certain
way. In this scenario, it is critical to determine why Lyndsi
made changes to her diet in order to have a better feel for
her potential risk of developing an eating disorder. For this
example, assume that Lyndsi is merely ignorant of how the
changes she has implemented can potentially negatively
affect her health and performance.
3. Because her calorie intake is low, she should increase her
daily calories, but gradually. The sports nutrition
professional should ensure that Lyndsiâ€™s questions,
concerns, and fears are addressed prior to suggesting the
revised meal plan. The revised meal plan (refer to Training
Table 13.1) provides adequate nutrients for growth,
development, health, and performance. Even though the
revised plan is at the lower end of the recommended
range, it may take a couple of weeks to gradually progress
her intake to the new level. The more gradual the process,
the easier it will be for Lyndsi to adapt physically and
mentally to the increased number of calories. Once she
reaches the minimum requirement for calories, the revised
meal plan can be reevaluated and adjusted accordingly.
How can calorie needs be calculated for athletes
aiming to maintain body weight while increasing
strength/power?
Nutrition becomes a focus for some athletes who are trying to bring
their performance â€œto the next levelâ€ by optimizing their intake of
macro- and micronutrients. Often, these athletes are satisfied with
their current weight but feel something is missing in their daily
dietary regimen. For these athletes, energy needs should be
calculated to confirm that an appropriate calorie level is being
consumed, and then the focus should shift to establishing balance,
variety, and moderation within the diet.
Jakeâ€™s Case Study
Jake is a 25-year-old, 50-meter butterfly swimmer. He swam
competitively in high school and college and now trains and
competes periodically with the masterâ€™s swim team at the YMCA.
During high school and college, he ate â€œwhatever he wantedâ€ and
never gained an ounce because he was so active. He has been
at the same weight (165 pounds) since graduation, and he wants
to maintain that weight. He works full time, lives alone, swims 5
to 6 days a week, and volunteers as an assistant coach for a
high school team. Since he has become so busy, he has been
relying more on fast food (see TRAINING TABLE 13.2 ), which
he recognizes has affected his swimming performance and
energy levels (unlike the â€œglory daysâ€ of his high school and
collegiate career). He wants to stay fit, eat healthy, increase his
energy levels, and compete at several upcoming swim meets.
Training Table 13.2 Jakeâ€™s Initial and Revised
Meal Plans
Making recommendations. In this scenario, Jake has realized
he needs to make some changes to his diet to keep his energy
levels up, to meet his nutritional needs, to avoid weight gain, and
to swim at his best.
1. The first step is to calculate his energy needs:
REE = (15.3 Ã— BW in kg) + 679 = (15.3 Ã— 75) + 679 = 1,827 Total
energy needs = REE Ã— Activity factor = 1,827 Ã— (1.6â€“2.0) =
2,922â€“3,654 calories/day
Because Jake is not as active as he was in high school
and college, a moderate activity factor can be used (1.6â€“
2.0 versus 1.6â€“2.4).
2. The next step is to evaluate the adequacy of his current
intake by analyzing a food record. An excerpt from Jakeâ€™s
food record is listed in Training Table 13.2. As noted by the
nutrition analysis, Jake is consuming an appropriate
number of total calories; however, he is eating 37% of his
calories from fat. Therefore, dietary recommendations for
Jake should focus on substituting some of the high-fat
foods with lower-fat, more nutrient-dense options.
3. Jake maintains a busy schedule, so meal planning needs
to be simple and easy to follow. By making a few
adjustments to his food choices, keeping meal preparation
to a minimum, and taking time to plan ahead, Jakeâ€™s
revised meal plan will help him maintain his weight while
also rebalancing his daily macronutrient intake. See
Training Table 13.2 for Jakeâ€™s revised meal plan.
How can calorie needs be calculated for athletes
aiming to gain muscle mass to increase
strength/power?
Strength/power athletes who are aiming to gain weight need to
consume extra calories each day to support basic energy needs, the
energy demands of daily training, and the nutrient support for tissue
growth and development. The success of a plan for weight gain
depends upon both the quality and quantity of the diet as well as an
appropriate strength training and conditioning program. It is essential
that these two components go hand in hand; if increases in training
are not accompanied by extra calories, muscle mass can potentially
be used as an energy source, resulting in weight loss, and if extra
calories are consumed without the physical challenge of training,
extra calories will most likely contribute to larger fat stores.
Tissue growth of approximately 1 pound requires approximately 5
to 8 calories per gram.5,6 Because 1 pound of muscle weighs 454
grams, a reasonable estimate of total calories needed to produce 1
pound of muscle is a range of 2,300 to 3,600 calories. In general, no
more than 1 to 2 pounds of weight gain is recommended per week.
Therefore, an athlete would need to consume approximately 300 to
500 additional calories per day for a 1-pound lean weight gain per
week, or 600 to 1,000 additional calories for a 2-pound lean weight
gain per week, assuming all calories are used for muscle
construction. However, this assumption cannot always be made.
Although increasing daily calories is an effective way to gain weight,
researchers have found that only 30 to 40% of the weight gain is in
the form of lean mass when study participants are consuming an
extra 500 to 2,000 calories per day.7 It seems reasonable to assume
that the more dramatic the increase in daily calorie consumption, the
greater the percentage of gained weight will be in the form of fat.
The body can construct only a finite amount of muscle tissue daily;
above that level, extra calories are stored as adipose tissue.
Therefore, strength/power athletes should aim for a modest increase
in daily calorie consumption (300â€“500 calories/day) and be patient
The extra calories needed for a 1-pound weight gain can be
easily obtained by consuming a snack such as:
Two tablespoons of peanut butter on one slice of thick bread with
1 cup of milk = 370 calories
A 6-ounce yogurt with Â¼ cup of dry oatmeal and Â¼ cup of mixed
nuts = 310 calories
A can of tuna with 4â€“6 crackers and a banana = 395 calories
For individuals needing 600 to 1,000 calories, portion sizes
should be increased at each meal and at least one or two snacks
should be included throughout the day, such as:
Any of the preceding snacks
A smoothie made with 12 ounces of milk, 1 cup of frozen fruit,
and a scoop of protein powder = 470 calories
Four to 6 ounces of turkey in a whole wheat pita with lettuce and
tomato = 410 calories
A canned nutrition drink or a large energy bar (no more than one
supplement item per dayâ€”focus heavily on whole foods) = 255
to 360 calories
Leoâ€™s Case Study
Leo is a 45-year-old recreational cyclist and weight lifter. He
commutes to work on his bike daily and goes to the gym 4 to 5
days per week for weight-lifting sessions. His goal is to gain 5 to
10 pounds of muscle mass (current weight, 170 pounds), but he
is having a hard time gaining any weight. He follows a wellbalanced strength-training program and changes his routine
every 6 to 8 weeks. He is currently eating three meals a day and
sometimes a snack. He wants to gain weight in a healthy way
and not rely on candy bars and chocolate shakes to add calories
to his diet. However, when he increases his intake through fruits
and vegetables, he experiences some gastrointestinal bloating
and discomfort. He is frustrated about his inability to gain weight
and is looking for advice from a professional.
Gaining the Performance Edge
Strength/power athletes must be provided with a sufficient
number of calories per day to meet energy needs or performance
will suffer. Total energy requirements should be calculated on an
individual basis and modified according to the athleteâ€™s goals and
objectives. Take into consideration an athleteâ€™s current intake
before making final recommendations to avoid drastic and
unrealistic changes.
Making recommendations. Leoâ€™s complaints are common among
strength/power athletesâ€”he has attempted to gain weight with little
to no success. Fortunately, he is dedicated to a healthy diet by
focusing not only on weight gain but also on long-term health.
However, in his attempts to add more food to his normal regimen, he
has chosen the two food groups with the lowest calorie densityâ€”
fruits and vegetables. Although whole fruits and vegetables are
certainly an important part of his overall diet, they may be
contributing to his sense of fullness and discomfort, ultimately
discouraging him from eating enough food to increase his total
calorie intake.
1. The first step is to determine how much he is currently
consuming. TRAINING TABLE 13.3 shows a typical day for
Leo. An analysis of his current intake reveals a total calorie
consumption of 3,527 calories. Therefore, it is obvious that he
needs to eat more than 3,527 calories a day to make any
progress in gaining weight.
Training Table 13.3 Leoâ€™s Initial and
Revised Meal Plans
2. The next step is to calculate total energy needs based on his
age and activity level. Using the formulas stated in Table 13.1,
his total daily energy needs are:
REE = (11.6 Ã— BW in kg) + 879 = (11.6 Ã— 77.3) + 879 = 1,775 Total
calorie needs = REE Ã— Activity factor = 1,775 Ã— (1.6 â€“ 2.4) = 2,840â€“
4,260 calories/day
Because he is currently consuming ~3,500 calories and he is
not gaining weight, the lower end of the spectrum can be
eliminated. For him to gain weight gradually, he will need to
consume approximately 3,800 to 4,200 calories per day. This
range would provide additional calories above his current
intake, while staying within the calculated estimate.
3. Leo should be congratulated on adding fruits and vegetables
to his diet. However, consuming more nutritious and caloriedense foods should be the focus of his weight gain efforts.
Foods that provide excellent nutrition and extra calories
include items such as fruit juices, dried fruits, avocados,
olives, thick breads, nuts, seeds, yogurt, instant breakfast
mixes, and fruit/milk smoothies. See TABLE 13.2 for more
ideas on how athletes can gain weight in a healthy way by
eating nutrient- and calorie-dense foods. Leo should maintain
balance in his diet by eating items from every food group of
the MyPlate food guidance system. Discourage Leo from
focusing on one type of macronutrient or food group as the
sole source of added calories. Balance, variety, and
moderation are still his keys to success. Refer to Training
Table 13.3 for Leoâ€™s revised meal plan, which provides 4,157
calories per day.
Table 13.2
Gaining Weight the Healthy Way Through Nutrientand Calorie-Dense Foods
Foods
Nutrient- and calorie-dense
options
Grains
Oatmeal, Cream of Wheat
Brown rice, quinoa
Bagels
Wheat germ
Muffins
Fruits
100% fruit juice
Dried fruit
Pineapple
Bananas
Vegetables
Potatoes
Corn
Peas
Squash
Beets
Olives
Dairy (milk alternatives) Nonfat powdered milk
Cottage cheese
Instant breakfast mixes
Fruited yogurts
Canned shakes (e.g., Ensure)
Protein foods (meat
alternatives)
Beans (e.g., pinto, black, kidney),
lentils
Split peas
Nuts and nut butters
Seeds
Meats
Foods
Nutrient- and calorie-dense
options
Desserts
Puddings
Fig bars
dairy products
Food for Thought 13.1
Considerations for Gaining Weight
In this exercise, you will identify the components necessary for
eliciting weight gain.
How are calorie needs calculated during
strength/power training and competition?
Energy needs for strength/power athletes can vary greatly between
a training session and a competitive event. Training sessions can
last several hours, whereas performance at a competition may last
only seconds or minutes. Therefore, these two scenarios should be
Similar to endurance athletes, consuming appropriate amounts of
energy, mainly in the form of carbohydrates, during training
sessions, will help to delay fatigue. Carbohydrate intake of 30 to 60
grams per hour is appropriate, providing approximately 120 to 240
calories per hour. Strength/power athletes add the element of
repeated high-intensity bursts of effort throughout a typical training
session. This factor mandates the need for energy sources that are
easily digestible to avoid gastrointestinal discomfort. Sports
beverages are an ideal source of calories and are generally well
tolerated even during high-intensity exercise. The consumption of
solid food should be reserved for during breaks or at the end of a
training session.
Gaining the Performance Edge
A majority of required calories for strength/power activities should
be consumed before or after exercise sessions to avoid
gastrointestinal upset and the subsequent interference with
training. Consuming sports beverages throughout a practice or
eating a light snack during a break will provide the energy
needed to fuel high-intensity performance.
For some strength/power athletes, competition day consists of
only one event that lasts less than a few minutes. In these situations,
it is neither practical nor necessary to consume calories during the
event. The body will not deplete its energy reserves in such a short
burst of effort, and therefore, immediate replenishment is not critical
to performance. The exception to this rule is when an athlete is
competing in multiple events at the same meet within 1 day. In this
situation, the length of the meet can last several hours, with a small,
but progressive, depletion of energy stores with each event.
Therefore, to sustain a high level of performance throughout the day,
an athlete should plan on consuming easy-to-digest snacks,
beverages, and possibly small meals in between events to keep
energy levels elevated. The quantity of food consumed will depend
upon several factors, including time between events, length of each
event, time elapsed since the last full meal, and personal
preferences.
Gaining the Performance Edge
To meet calorie needs, strength/power athletes should focus on
consuming calorie-containing beverages and easily digestible
snacks during training sessions and half- or full-day competitive
meets. However, during single-bout events, it is neither practical
nor necessary to consume any food or beverage.
Are carbohydrate needs different
for strength/power athletes?
Consuming enough carbohydrates on a daily basis is critical
for optimal strength/power performance. Because many
strength/power sports rely on anaerobic metabolism,
carbohydrates are the main fuel for these short, high-intensity
bursts of energy. Anaerobic metabolism taps into glycogen
stores for energy during an activity; therefore, if glycogen
stores are depleted, performance will suffer.
Similar to endurance exercise, strength/power exercise
can deplete muscle glycogen, although not to the same
degree. Several studies have examined the glycogendepleting effects of strength training. Tesch and colleagues13
found a 25% decline in muscle glycogen stores after subjects
performed five sets of four different leg exercises for 6 to 12
repetitions each. Other protocols involving five to six sets of
six to 12 repetitions at 35 to 70% of maximal strength
produced a similar reduction in glycogen stores.13,10
Therefore, it has been suggested that the ingestion of higher
carbohydrate diets will improve performance through higher
initial glycogen levels. Several studies have supported this
recommendation after examining the effects of a high-versuslow carbohydrate diet prior to performing a single bout, as well
as intermittent, high-intensity activities.11â€“14 Strength/power
athletes should strive for a moderate to high intake of
carbohydrates daily to have fully loaded glycogen stores
before training sessions and competitive events.
A possible exception to the rule of glycogen stores making
an impact on strength/power performance is during a single
sprint effort. During one sprint of about 400 meters or fewer,
the quantity of muscle glycogen stored in the muscle is not
necessarily the limiting factor in performance.15
Carbohydrates are still the main source of fuel; however,
because of the short duration of the effort, glycogen stores will
not be depleted by one burst of sprinting. Therefore,
would be before a training session or other repeated highintensity exercise bouts. Sprinters may train intensely several
times per week, including repeated sprints per workout, so
moderate carbohydrate consumption on a daily basis is a
sound dietary practice.
In addition to fueling activity, carbohydrate intake can play
an indirect role in building muscle mass. Carbohydrate
ingestion stimulates the secretion of insulin. Insulin is
considered an anabolic hormone, driving nutrients into the
cells for the growth and development of tissues as well as
preventing normal postexercise muscle protein
carbohydrates, as well as ensuring that total energy and
protein needs are met, will support muscle growth in response
to the demands of an appropriate strength training and
conditioning program.
How are daily carbohydrate needs
calculated for strength/power athletes?
Many strength/power athletes will train intensely three to five
times per week; without sufficient dietary carbohydrate intake,
this could lead to glycogen depletion and decreased
performance. An intake of 6 to 10 grams of carbohydrates per
kilogram of body weight per day has been shown to replenish
glycogen stores after daily training sessions.18 However,
based on an athleteâ€™s training regimen, carbohydrate
recommendations might range from 3 to 10 grams per
kilogram of body weight.19 Carbohydrate intake should
contribute approximately 55 to 65% of total calorie intake.
This percentage can also be used to estimate carbohydrate
needs based on total calorie requirements.
Estimated carbohydrate needs should be compared with
total estimated energy requirements to verify that
carbohydrate recommendations fall near the range of 55 to
65% of total calories. Building on the scenarios described in
the last section regarding Lyndsi, Jake, and Leo, the following
examples demonstrate the importance of fine-tuning
carbohydrate recommendations for every athlete:
Lyndsi, the gymnast, requires 259 to 432 grams of
carbohydrates daily based on the 6 to 10 grams of
carbohydrates per kilogram of body weight
recommendation (95 lbs Ã· 2.2 = 43.2 kg; 43.2 kg Ã— 6â€“10
g/kg = 259â€“432 g). Lyndsiâ€™s initial meal plan analysis
revealed that she was consuming 66% of her total calories
from carbohydrates. Although this percentage sounds
appropriate, the absolute value of her carbohydrate intake
was only 153 grams, which is only 59% of the low end of
her recommended carbohydrate intake range. In addition,
Lyndsiâ€™s absolute carbohydrate intake is only slightly
higher than the RDA for carbohydrates (130 grams) for
adults and children based on the average minimum
amount of glucose utilized by the brain daily.20 In Lyndsiâ€™s
revised meal plan, the percentage of calories from
carbohydrates decreased to 56%; however, the absolute
value of her intake increased to 290 grams. This number is
within the 259 to 432 recommended range and represents
an 89% increase from her previous carbohydrate
consumption.
Jake, the swimmer, requires 450 to 750 grams of
carbohydrates daily based upon the 6 to 10 grams of
carbohydrates per kilogram of body weight
recommendation (165 lbs Ã· 2.2 = 75 kg; 75 kg Ã— 6â€“10 g/kg
= 450â€“750 g). In this case, 450 grams of carbohydrates
contribute 1,800 calories (450 g carbohydrates Ã— 4
calories/g carbohydrates = 1,800 calories). This quantity of
carbohydrates represents 62% of 2,922 calories (the low
end of his recommended calorie range) and 49% of 3,654
calories (the high end of his recommended calorie range).
Clearly, 450 grams of carbohydrates would be appropriate
for a calorie intake at the low, but not the high, end of his
recommended range; therefore, it is more appropriate to
estimate his carbohydrate needs through a percentage of
total calories. For example, 55 to 65% of Jakeâ€™s high-end
calorie range (i.e., 3,654 calories) equals:
([0.55â€“0.65] Ã— 3,654 calories)/ 4 calories per gram of
carbohydrates = 502â€“594 grams of carbohydrates daily
Gaining the Performance Edge
Carbohydrates are the master fuel for strength/power
sports. Consuming adequate amounts of carbohydrates on
a daily basis ensures glycogen stores will be sufficient to
support high-intensity training and competition.
Carbohydrates also act as a support crew for the
construction of muscle mass in response to resistance
training.
For Jake, estimating an appropriate amount of
carbohydrates varies greatly depending upon his total calorie
intake. Therefore, a final carbohydrate recommendation for
Jake is 450 to 594 grams of carbohydrates per day. Jakeâ€™s
revised meal plan provides 468 grams of carbohydrates, thus
meeting his daily needs.
Leo, the weight lifter, requires 464 to 773 grams of
carbohydrates daily based on the 6 to 10 grams of
carbohydrates per kilogram of body weight
recommendation (170 lbs Ã· 2.2 = 77.3 kg; 77.3 kg Ã— 6â€“10
g/kg = 464â€“773 g). Because Leo is attempting to gain
weight and thus has higher calorie needs, the estimated
carbohydrate intake based upon body weight should be
checked using the percent total calories method.
By comparing the body weight recommendation range
of 464 to 773 grams of carbohydrate to that of the
percentage of total calories range (i.e., 522â€“682 grams), it
is apparent that an adjustment is needed for his minimum
intake recommendation. In this case, the minimum value
of the body weight recommendation range (i.e., 6 grams
per kilogram of body weight, or 464 grams) is too low
because it accounts for less than 55% of total calories. As
a result, adjusting the minimum recommendation to 522
grams is warranted. If you convert the 522 grams of
carbohydrate into a gram per kilogram body weight
recommendation, it would be 6.8 grams per kilogram of
body weight (i.e., 522 g/77.3 kg = 6.8 g/kg).
Leoâ€™s initial meal plan was providing only 399 grams of
carbohydrates per day. The revised meal plan increased
his intake to 53% for a total of 612 grams of carbohydrates
per day.
Keep in mind that these scenarios provide only three
examples of individual athlete needs. Most of these cases
suggest 55 to 65% of total calories from carbohydrates;
however, this recommendation can be raised or lowered
based on the volume of training that a strength/power athlete
engages in daily. None of these cases recommended
carbohydrate intakes at the high end of the rangeâ€”10 grams
of carbohydrates per kilogram of body weight. This does not
mean that 10 grams of carbohydrates per kilogram of body
weight is not appropriate in some situations. Evaluate each
athlete individually, compare estimations to current intake,
and then make recommendations based on the athleteâ€™s
goals and training schedule. FIGURE 13.2 compares the
individual carbohydrate and energy needs of the three
athletes discussed here. Each of these athletes has different
energy and carbohydrate needs based upon his or her body
weight, gender, and strength-training program.
Figure 13.2 Lyndsi, Jake, and Leo have different energy and
carbohydrate needs based upon their size, sport, and training level.
Images
Are carbohydrates needed before and
during training and competition?
The performance effects of carbohydrate ingestion
immediately prior to and during strength/power sports are
unclear. The limited research available presents evidence to
support a variety of benefits and potential drawbacks. Thus,
trade-offs exist, requiring recommendations and nutrition
plans to be individualized based on the goals and objectives
of the athlete and a consideration of the specific activity to be
performed.
Although engaging in strength/power sports generally
does not cause a reduction in blood glucose levels during a
workout, a considerable glycogenolytic effect has been
observed during either intermittent, high-intensity exercise or
strength-training-type activities.8,10,21,22 If depletion of
glycogen occurs, performance suffers as a result of fatigue,
and over the long term, the athlete can experience muscle
loss. Therefore, it appears prudent to consume carbohydrates
before, and also during, strength/power exercise.
A general recommendation for preactivity eating is to
consume a carbohydrate-rich meal approximately 1 to 4 hours
prior to the initiation of exercise. The provision of
carbohydrates helps to top off the bodyâ€™s glycogen stores prior
to training or competition. Many athletes find that the
consumption of carbohydrates before a hard training session
allows them to complete a tough workout without feeling
fatigued prematurely. Therefore, athletes push themselves
harder and gain more benefit from the workout. Furthermore,
recent research has suggested that the provision of
carbohydrates, as well as amino acids, prevents muscle
breakdown during intense exercise, potentially leading to a
maintenance or enhancement of muscle mass.17
Additional benefit has been observed when athletes
supplement the preactivity meal with a supply of
carbohydrates during the workout or competition, typically in
the form of a beverage or liquid supplement. Especially for
long training sessions, consuming carbohydrates periodically
during exercise sustains energy levels and work output for
longer periods of time.23,24 In a well-designed study, Haff et
al.23 aimed to determine the performance effects of
carbohydrate supplementation on the ability to perform
resistance exercise during a second training session on the
same day. Subjects performed a glycogen-depleting session
of resistance training in the morning (15 sets of various lower
body exercises) and then returned to the gym 4 hours later to
squat to exhaustion. The carbohydrate-supplemented group
outperformed the placebo group by successfully completing a
greater number of sets and repetitions. Although higher
energy levels and greater strength/power outputs during a
training session, because of carbohydrate intake, sounds like
a â€œno-brainer,â€ not all research findings have yielded similar
results.25,26 In fact, some athletes, coaches, and researchers
are suggesting the exact opposite nutrition practiceâ€”avoiding
carbohydrates before and during training.
This school of thought exists mainly in the world of weight
lifting and body building. It is based on the premise that a
steady stream of carbohydrates into the bloodstream will
prevent the body from tapping into other energy sources,
specifically fat stores. Therefore, the recommendation is to
avoid eating carbohydrate-rich foods 1 to 4 hours prior to
exercise. In fact, most recommend not consuming any food
before a workout. The second half of the recommendation
includes the avoidance of carbohydrate beverages,
supplements, and food during a workout. Although this
practice will cause the body to turn to fats (adipose tissue and
intramuscular fats) for energy, it is well known that when
glycogen and blood glucose levels begin to run low, the
athlete will begin to tire, perception of effort increases, and
performance levels can plunge. However, not all athletes
experience extreme fatigue, particularly if their diet is
adequate at other times of the day when following this
practice; therefore, the final recommendation will be based
upon individual preference and tolerance. If an athlete
chooses to avoid consuming food before and during a
strength/power workout, a strong emphasis should be placed
on consuming the required number of daily calories
throughout the rest of the day. Obviously, this carbohydrate
avoidance scenario is best implemented with early morning
workout sessions to prevent the disruption of regular meal
times throughout the day.
Gaining the Performance Edge
Trade-offs exist in the â€œto eatâ€ or â€œnot to eatâ€ schools of
thought regarding consuming carbohydrates before and
during strength/power sports. Currently, most research
suggests that supplying the body with carbohydrates
before and during exercise will lead to greater gains in
strength/power performance. Athletes should try both
methods and determine which recommendation is ideal in
helping the athlete reach his or her goals and performance
potential.
The final recommendation should be based on an athleteâ€™s
preference for carbohydrate consumption, the effects on
performance, and the safety of the athlete. Some athletes feel
they perform better on an empty stomach, whereas others
become hungry, distracting them from performing well. In
terms of safety, if blood glucose levels run too low, athletes
can pass out and injure themselves, especially during an
activity such as weight lifting. Athletes should test both
methods during practice sessions and determine which
recommendation leads to improved performance, increased
strength/power, overall safety of the athlete, and a feeling of
well-being that they are meeting their goals. At the same time,
researchers will continue to examine the effects of
macronutrients on strength/power performance and eventually
determine specific nutritional guidelines.
Are carbohydrates needed for recovery from
strength/power activities?
Similar to endurance sports, strength/power activities can
deplete glycogen stores, requiring carbohydrate consumption
after exercise. Complete replenishment of glycogen stores
can take as little as 4 to 6 hours and up to 24 to 48 hours
depending on exogenous carbohydrate availability. It is in the
athleteâ€™s best interest to consume carbohydrates immediately
following exercise as well as throughout the day at regular
meals and snacks.
Athletes should focus on the timing and quantity of
carbohydrates consumed after exercise. A source of
carbohydrates should be eaten as soon as possibleâ€”ideally
within 15 to 30 minutesâ€”after the cessation of exercise. This
will ensure that the carbohydrates are digested and delivered
to muscles in the window of time in which the muscles are
most receptive to absorbing and storing carbohydrates as
glycogen for the next training session. Ideally, athletes should
ingest 1.0 to 1.2 grams per kilogram of body weight every
hour for 4 hours postexercise.19 Consuming enough
carbohydrates is more important than the exact type of
carbohydrates. Fruits, vegetables, juices, whole grains, lowfat milk, and dairy products are some of the best choices to
supply carbohydrates.
Although the provision of carbohydrates after highintensity exercise is critical for glycogen replenishment, it has
also been suggested that it plays a role in muscle adaptation
after intense training. However, carbohydrates cannot act
alone in this role; muscle protein synthesis will be much
greater when a combination of carbohydrates and protein is
consumed immediately after exercise.27 The quantity and
timing of this macronutrient combination for muscle growth
and development will be addressed in the upcoming sections
on protein needs for strength/power athletes.
Carbohydrates may be important not only for the
replenishment of glycogen stores and muscle construction but
also for the attenuation of immunosuppression observed after
exercise. Many studies have reported that high-intensity
exercise suppresses immune function temporarily after
exercise.28â€“31 It has been suggested that ingestion of
carbohydrates before, during, and/or after exercise may
minimize the immune function changes in athletes, leading to
less risk of illness.31â€“35 Many of the studies related to
immunosuppression have been conducted with endurance
athletes. However, Chan et al.32 researched the effects on
immune function of carbohydrate consumption before and
after resistive exercises. Subjects consumed a lowcarbohydrate meal 2 hours prior to the strength-training
session. Ten minutes prior to exercise and 10 minutes after
exercise, subjects drank either a carbohydrate supplement
beverage (one trial) or placebo (second trial). The researchers
reported that carbohydrate ingestion minimized the decrease
in interleukin-2 and interleukin-5 (an indication of greater
immune function compared with controls) after exercise. More
research is needed in this area to verify these results.
However, carbohydrate consumption after strength/power
exercise is important for glycogen resynthesis and muscle
construction regardless of its effect on the immune system. If
research does reveal that carbohydrate consumption
surrounding high-intensity, short-duration exercise has a
positive effect on immune function, it will be a bonus benefit to
Gaining the Performance Edge
Carbohydrates are the master fuel for strength/power
athletes. Each athlete should experiment with different
quantities of foods and beverages to determine his or her
individual â€œidealâ€ plan for before, during, and after
exercise.
Are protein needs different
for strength/power
athletes?
The high intensities that strength/power athletes train
at on a daily basis challenge the body and skeletal
muscle. This â€œchallengeâ€ creates microscopic tears in
muscle tissue, which are the stimuli for subsequent
tissue repair and rebuilding. Amino acids, either
synthesized by the body or obtained from the
digestion and breakdown of dietary protein, are the
building blocks for muscle repair and rebuilding.
Because of this function, protein has long been a
major dietary focus for strength/power athletes. The
mantra has typically been â€œthe more protein, the
better.â€ Although strength/power athletes do have
higher protein needs than their sedentary
counterparts, an overdose of protein intake on a
daily basis is not ergogenically beneficial.
How are daily protein needs
calculated for strength/power
athletes?
Strength/power athletes have an increased
requirement for dietary protein. Muscle tissue goes
through a process of self-repair on a daily basis, and
therefore, sufficient amounts of high-quality protein
sources need to be consumed at every meal. Dietary
proteins are digested and broken down into amino
acids, which the body then uses for building blocks
for all bodily tissues. Insufficient protein intakes will
lead to suboptimal improvements in muscle
development, low energy levels, and poor
performance. However, excessive protein intakes
body composition, and overall health.
Strength/power athletes need to find the right
balance between these two extremes. In addition to
the total protein intake, the variety of protein sources
ingested is also of importance.
How do you determine the â€œoptimalâ€
daily dose of protein for
strength/power athletes?
The true â€œoptimalâ€ quantity of daily protein intake for
strength/power athletes has been debated over the
years. A few articles have reported that active
individuals become more efficient at using protein on
a daily basis, and therefore, protein needs actually
decline rather than increase in athletes.27,36
However, a majority of the current research points to
protein needs in the other direction, at the higher end
of the scale. Some researchers suggest that a range
of 1.2 to 1.7 grams of protein daily per kilogram of
body weight is appropriate,37 whereas others
recommend a higher upper limit of 2.0 grams of
protein per kilogram of body weight.19,38 Magazines,
coaches, practitioners, and athletes often push the
upper limit even higher, to levels greater than 2.5 to
3.0 grams per kilogram of body weight. The bottom
line is that strength/power athletes do have
increased protein needs; however, there is a limit to
the amount of protein that can be used effectively
Since the early 1980s, studies have revealed that
dietary protein plays an integral role in muscle
growth and development. Although not all the
parameters affecting muscle protein synthesis have
been identified, a few factors such as increased
insulin levels and availability of amino acids are
obvious. A decline in intracellular amino acid
concentration will inhibit protein synthesis.
Strength/power exercise has been shown to elicit a
decrease in amino acid concentrations.39,40
Therefore, it seems to follow that the ingestion of
protein or amino acids would prevent this decline
and, in turn, stimulate protein synthesis. In fact,
studies have shown that the consumption of dietary
proteins, which increases endogenous amino acid
availability, can stimulate an increase in muscle
protein synthesis by 30 to 100%.27,41 Muscle growth
and development are largely caused by an enhanced
protein synthesis versus a decreased muscle
breakdown.42 Therefore, daily, and particularly, preand postworkout provision of amino acids is of the
utmost importance in maximizing muscle building.
Because of the essential role of protein and
amino acids in the growth and development of
muscle tissue, a common misconception is that by
increasing protein intake, an athlete can increase
muscle mass. As stated in the previous paragraphs,
there is no doubt that protein is critical for muscle
growth. However, once an athlete has reached the
peak of protein assimilation, additional protein will
not be used to create even more muscle tissue.
Physical training is the strongest stimulus for
signaling the muscles to grow and develop. Proper
nutrition acts as a support network to the training
stimulus; however, it does not necessarily initiate a
further stimulus when consumed in quantities that
significantly surpass physical requirements. To
increase muscle mass, the equation is simple: Train
hard and eat well, but do neither in excess.
Similar to carbohydrates and fat, athletic
performance and overall health can suffer if too
much protein is ingested and macronutrient balance
goes astray. Excessive daily protein intake is
generally considered to be greater than 2.0 grams of
protein per kilogram of body weight (except in cases
of injury rehabilitation, intensified training, or during
times of reduced energy intake). At intakes above
this level, protein is either used for fuel or converted
and stored as fat. Second, increased protein
digestion and breakdown result in greater urea
production, thus causing more fluid to be excreted
from the body to flush out the toxic urea, potentially
leading to dehydration. Third, if calories remain
stable and protein intake increases, carbohydrate
intake and glycogen replenishment generally suffer,
ultimately affecting workouts. Finally, high-protein
foods, especially animal products, tend to be high in
fat, saturated fat, and cholesterol, all of which can
negatively affect cardiovascular health. As with most
nutrients, more is not always better.
How do you determine the â€œoptimalâ€
food sources of protein?
In the world of strength/power athletes, â€œhigh-qualityâ€
and â€œcompleteâ€ proteins receive the most attention.
Although the quality of a protein is certainly
important, true success is achieved with variety. It
should be noted that the term incomplete protein
often is misinterpreted as meaning â€œinadequateâ€ or
â€œuselessâ€ for strength/power athletes. This
interpretation is erroneous and misleading. The
bottom line is that all sources of protein are valuable
for the strength/power athlete. To maximize the
benefits of dietary protein, consider putting into
practice the tips outlined in TRAINING TABLE 13.4 .
Training Table 13.4 Tips for
Maximizing the Benefits of Dietary
Protein for Strength/Power Athletes
Consume enough total calories to meet energy
needs. If calorie intake declines, a higher
percentage of ingested protein will be used for
energy versus for muscle building and repair.
Consume a level of protein that falls within 1.4
to 2.0 grams of protein per kilogram of body
weight. This level of protein generally
contributes 15 to 20% of total calories. Athletes
should ensure that plenty of carbohydrates and
at least minimum amounts of fat are also
ingested daily.
Include a protein source in every meal and
snack. By focusing on including a protein
source at every meal and snack, protein is
throughout the day. This recommendation is
especially important for athletes engaging in
multiple training sessions daily.
Choose a variety of different protein sources.
Lean meats, poultry, fish, and dairy products
are excellent choices because of their amino
acid profile and high overall protein content.
Vegetarians should consume plenty of soy
products, which also contain an ideal amino
acid profile and high protein content. Beans,
lentils, nuts, seeds, and grains supply protein
in smaller amounts and with low levels of one
or two amino acids. By consuming a variety of
these sources on a daily basis and in larger
quantities, strength/power athletes can achieve
optimal intakes of protein.
Consume protein supplements in moderation,
if necessary. In general, protein needs can be
met through â€œrealâ€ foods consumed throughout
the day. Studies have shown that supplemental
protein provides no added benefit over whole
food sources.39 However, if an athlete is
already eating a well-balanced diet but is still
having a hard time obtaining optimal quantities
of protein, a supplement can be used in
moderation. Protein powders are an
appropriate supplement to use because a
powder can be added to â€œrealâ€ foods such as
milk, yogurt, cereal, and smoothies.
Do individual amino acids have an
ergogenic effect on muscle growth
and development?
The ingestion of specific amino acids or groups of
amino acids has been purported to enhance muscle
strength and development. It has been suggested
that amino acids can influence muscle strength and
development through the initiation of protein
synthesis and/or increase the secretion of various
anabolic hormones. The current research provides
some insight into the action of various amino acids,
but more research is needed to make firm
conclusions and subsequent dietary
recommendations.
Glutamine is one of the most popular amino acid
supplement products on the market because of its
touted â€œanticatabolicâ€ effects with regard to skeletal
muscle. It is the most abundant amino acid found in
blood plasma and skeletal muscle43 and accounts for
more than 60% of the total intramuscular free amino
acid pool.44 However, glutamine is in high demand
by other tissues of the body. For example, glutamine
is needed by the cells of the gastrointestinal system
to support their continual high protein synthesis
rates. Glutamine is also used as a fuel source for
cells of the immune system and hair follicles.44,45 As
a result, if glutamine levels are not sufficient to meet
the bodyâ€™s total needs, particularly during periods of
high stress such as intense training, glutamine is
taken and/or synthesized from amino acids present
in skeletal muscle. It appears that glutamine not only
prevents muscle catabolism, but several studies
have reported that glutamine is also critical for
protein synthesis within skeletal muscle.46,47
Although the current research appears promising,
the long-term effects of glutamine supplementation
on protein synthesis and body composition have yet
to be confirmed. As a result, more research is
needed before conclusions can be drawn and
supplementation.
The branched chain amino acids (BCAAs),
particularly leucine, have been suggested to be
positive regulators of muscle protein synthesis.48
However, the research on the effects of the BCAAs
on exercise performance is ongoing. The exact
actions of these amino acids before, during, and
after exercise and the subsequent requirements and
recommendations for intake are yet to be elucidated.
The increased secretion of growth hormone is
at the center of many amino acid supplement claims;
however, study results have shown mixed
conclusions. For example, Suminski et al.49 reported
that 1,500 milligrams of arginine and 1,500
milligrams of lysine consumed at rest increased
growth hormone levels 60 minutes after ingestion.
However, the same quantity of amino acids provided
immediately prior to weight lifting did not alter
circulating growth hormone levels in males while
exercising. Amino acids and their respective
influence on insulin, testosterone, and cortisol have
also been highlighted as potential factors in protein
metabolism and synthesis. Once again, more
research is needed to ascertain the connections and
interactions of amino acid ingestion and hormonal
responses and the subsequent effects on protein
metabolism and muscle protein synthesis.
Is protein needed before and during
training sessions and competitions?
The benefits of consuming protein before
strength/power sports have recently received more
attention in the research. Most of the studies have
explored not only the effects of protein but also the
combination effect of carbohydrates and protein on
muscle synthesis, catabolism, and performance. The
influence of ingesting protein during training or
competition on strength/power performance has
received minimal attention, and therefore, the
relationship between these two factors is still under
investigation.
Until recently, many of the recommendations
related to nutrition and muscle building have focused
on the recovery period. Although the 1 to 4 hours
after exercise are still considered a critical time for
replenishment, it may not be the only time when the
athlete can affect muscle and strength gains. The
argument for consuming both protein and
carbohydrates before strength/power training is
based on the anabolic effects of increasing the
secretion of insulin and circulating amino acids. By
consuming carbohydrates before strength/power
exercise, insulin levels will rise and thus decrease
the normal exercise-induced catabolism of muscle
tissue.50,51 A supply of exogenous protein results in
a greater delivery and increased concentration of
intracellular amino acids in the muscle during
exercise, enhancing protein synthesis.40 Although
the action of carbohydrates and protein is the same
after exercise, the reason that preactivity
consumption is preferable to postactivity is related to
blood flow. The theory is that when the concentration
of nutrients (through the digestion of a preactivity
carbohydrateâ€“protein source) and blood flow
(caused by exercise) are both increased, the rate of
nutrient uptake and utilization as well as protein
synthesis is maximized.40 The positive effects of
consuming carbohydrates and protein prior to
exercise have been reported with the consumption of
10 grams of essential amino acids (15â€“25 grams of
high-quality protein) and 35 grams of
carbohydrates.19 Therefore, large volumes of food
do not need to be consumed to gain the anabolic
benefits.
Gaining the Performance Edge
Until further research is conducted to elucidate
the benefits and drawbacks of consuming
individual or groups of amino acids, the best way
for athletes to obtain amino acids is from proteinrich, whole foods eaten daily in appropriate
amounts.
Strength/power athletes should strongly consider
consuming a source of both carbohydrates and
protein before a training session to maximize the
ability of the body to synthesize new proteins. The
benefit of consuming additional protein during
strength/power sports still needs to be determined.
Is protein needed for recovery from
strength/power activities?
High-intensity exercise and strength training
stimulate protein synthesis in muscle tissue. In
response to this physical stress, amino acids are
released from the free amino acid pools within
plasma and cellular spaces of the body.52,53 To meet
the basic metabolic needs of muscle tissue, to repair
damage from high-intensity exercise, and to build
new muscle tissue, exogenous amino acids are
required. Therefore, protein is a critical component of
any strength/power athleteâ€™s postexercise meal or
snack.
Several studies have examined the effects of
consuming macronutrients at various intervals after
exercise to determine an ideal environment for
muscle synthesis and recovery from training. It
appears that the provision of amino acids after
resistance exercise stimulates greater protein
synthesis, producing a net positive effect (more
synthesis versus breakdown compared with fasting
after exercise).54 When a combination of essential
amino acids (6â€“10 grams) and carbohydrates (35
grams) is provided, an even greater increase in
protein synthesis is observed.42 The current
recommendation is to consume 15 to 25 grams of
protein, or 0.25 to 0.30 grams of protein per kilogram
of body weight, after exercise.19 Consuming a
combination of carbohydrates and protein both
before and after high-intensity training will be
beneficial for protein synthesis.
A study conducted by Chandler55 and colleagues
reported that the combination of carbohydrates and
protein was more advantageous than either
carbohydrates or protein alone in stimulating
anabolic hormone secretion after resistance
exercise. Subjects performed a standardized
resistance training workout and then consumed an
isocaloric amount of one of three supplements
(carbohydrates only, 1.5 g/kg; protein only, 1.38 g/kg;
or carbohydrates and protein, 1.06 g/kg and 0.41
g/kg, respectively) immediately and 2 hours after the
session. Both the carbohydrates and carbohydrateâ€“
protein supplements caused an increase in
circulating insulin levels. However, only the
caused a modest but significant increase in growth
hormone levels. The results of this study reveal that
the combination of carbohydrate and protein
ingestion after strength training can produce a
hormonal environment during recovery that may be
favorable to muscle growth.
A study performed by Rassmussen et al.56
provided more evidence that a combination of
protein and carbohydrates after resistance training
stimulates muscle protein synthesis. In their study,
six subjects randomly consumed a treatment drink (6
grams of essential amino acids, 35 grams of
sucrose) or a flavored placebo drink one to three
hours after a bout of resistance exercise on two
separate occasions. Muscle protein synthesis was
significantly increased over the placebo drink at both
the one and three hour dose periods. The end result
was that essential amino acids combined with
carbohydrates stimulate muscle protein anabolism
by increasing muscle protein synthesis up to three
hours postexercise.
Although the optimal balance and ideal quantity
of carbohydrates and protein to consume after
strength/power activities are yet to be determined,
athletes can gain an edge on competitors by
consuming a snack or full meal containing both
carbohydrates and protein to help recover after
training sessions or competitions. So the next
question is: When should these macronutrients be
ingested?
Similar to consuming carbohydrates immediately
after endurance exercise to optimize glycogen
replenishment, a combination of protein and
carbohydrates should be consumed as soon as
possible after strength/power activities. A proteinâ€“
carbohydrate food or beverage should be consumed
immediately following a training session or
competition, with benefits diminishing 1 to 3 hours
postexercise.56 This nutrition protocol will stimulate
the release of insulin to prevent muscle breakdown
while also supplying amino acids needed as building
blocks for muscle tissue.
Gaining the Performance Edge
Strength/power athletes should aim to consume
at least 15 to 25 grams of protein (0.25â€“0.30
grams protein per kilogram body weight) and 35
grams of carbohydrates as soon as possible after
training sessions and competitions. The
combination of carbohydrates and protein will not
only help muscle protein synthesis but also
glycogen replenishment.
Are fat needs different for
strength/power athletes?
Strength/power athletes burn very little fat during the
performance of their sport. The bioenergetic demands of the
forceful muscle actions performed by strength/power athletes
are met by the phosphagen and anaerobic energy systems,
neither of which relies on the metabolizing of fats for
production of ATP. Does that mean that strength/power
athletes do not need to consume fat? No. Essential fatty acids
are needed for the general health of all bodily tissues. Fats
are also attractive to the strength/power athlete because of
their caloric density. A moderate amount of fat should be
consumed on a daily basis, with an emphasis placed on
unsaturated fats. The timing of fat consumption is also of
importance to avoid any potential performance disturbance
during training or competition.
How are daily fat needs calculated for
strength/power athletes?
For strength/power athletes, the goal is to find the right
balance of carbohydrate, protein, and fat intake to supply all
essential nutrients and allow athletes to perform at their best.
Fat is a controversial topic requiring the consideration of
several factors, including caloric needs; the athleteâ€™s desire to
lose, maintain, or gain weight; health history; and ideal
sources of fat. All strength/power athletes need fat; however,
fat intake recommendations can vary greatly.
A general recommendation cited by Rogozkin18 suggests
a daily fat intake of approximately 2 grams of fat per kilogram
of body weight. This quantity of fat may be appropriate for
most athletes; however, as always, the calculated estimate
should be compared with total calorie needs before a final
recommendation is made to the athlete. For general health, a
fat intake of 30 to 35% of total calories is considered an upper
limit. A range of 20 to 25% is more appropriate for
strength/power athletes who are trying to lose weight because
fat is more calorically dense, and it takes less energy to
digest, absorb, and assimilate fats than carbohydrates and
proteins. What this means is that if excess calories from fatty
foods are ingested, more of the excess will be stored as fat
than if the excess calories had come from proteins or
carbohydrates. An athlete who is aiming to gain weight will
generally find the 25 to 30% range sufficient in supplying extra
calories as well as decreasing the total volume of food
needed to meet total energy needs. General health and
specific athletic goals/objectives should be considered when
estimating fat needs.
For example, consider two athletes who both weigh 150
pounds: one is a wrestler aiming to lose weight who
consumes about 2,500 calories per day, whereas the other is
a shot putter with the goal of increasing muscle mass who
requires 4,500 calories per day. Basing their fat needs on 2
grams per kilogram of current body weight, both athletes
would require 136 grams of fat per day. Comparing this
recommendation to estimated calorie needs, the percentage
of total calories from fat would be 49% and 27% for the
wrestler and shot putter, respectively. Knowing that the
wrestler wants to lose weight, that the fat intake
recommendation for overall health is no more than 30 to 35%
of total calories; that fat is calorically dense, making it easier
to err on the side of overconsumption; and that fats do not
increase the metabolic demands for digestion and absorption
like proteins and carbohydrates, the 136-gram
recommendation is not to the wrestlerâ€™s advantage. Using the
range of 20 to 25% of total calories from fat to estimate his
needs:
(2,500 calories Ã— [0.20â€“0.25])/9 calories per gram of fat =
55â€“69 grams of fat per day
Thus, 55 to 69 grams of fat per day will supply the wrestler
with a small amount of fat to provide satiety and essential fatty
acids, while minimizing the impact on total calorie intake. In
contrast, the 136 grams of fat calculated for the shot putter is
appropriate, providing a moderate amount of fat to allow the
athlete to meet his increased energy needs while maintaining
a healthy diet (see FIGURE 13.3 ).
Figure 13.3 Dietary fat consumed in moderation allows the
strength/power athlete to meet increased energy needs while maintaining
a healthy diet.
Strength/power athletes should also consider their health
history when consuming fats. Saturated and trans fats are the
most detrimental to health, whereas monounsaturated and
polyunsaturated fats are beneficial to overall health. For those
who are at risk for heart disease, high cholesterol, or cancer,
special attention should be placed on unsaturated fats. An
intake of mainly unsaturated fats is also considered protective
for future health problems for all athletes. Strength/power
athletes should be guided toward healthy types of fats,
especially those who are consuming large quantities of
protein, which are often rich sources of saturated fats. Protein
sources that are lower in total fat and saturated fat include
lean cuts of beef, chicken, turkey, fish, legumes, and soy
products.
Are fats needed before and during training
sessions and competitions?
Although fats are important to consume on a daily basis, fat
intake should be minimized in the hours leading up to, as well
as during, an intense training session or competition. Fats
take longer to digest, leading to a sense of fullness and
potentially gastrointestinal discomfort during exercise. Very
small amounts of fat can be included in a preexercise meal
consumed several hours prior to the initiation of exercise to
provide a feeling of satiety. However, a majority of fat intake
should be reserved for after training sessions and
competitions, spread evenly throughout the day.
Gaining the Performance Edge
Fats are an important component to an overall healthy diet
for strength/power athletes. Fat consumption should be
kept within the range of 20 to 35% of total calories, based
on total caloric needs and the athleteâ€™s goals and
objectives. Fats should be obtained from mainly
unsaturated sources, while minimizing saturated and trans
fat intake. The ingestion of fats before, during, and
immediately postexercise should be kept to a minimum.
Fats should be ingested in other meals and snacks spread
throughout the day.
Is fat needed for recovery from
strength/power activities?
It is not essential to replace any fat used during
strength/power exercise by consuming fat-rich foods
immediately following training or a competition.
Strength/power sports rely minimally on fat for energy during
training sessions and competitions, and therefore, fat
â€œdepletionâ€ is not an issue. Even if fat was used during
strength/power sports, the bodyâ€™s stores of fat are so great
that they will not be depleted in one workout. For athletes
aiming to lose weight and become lean, training sessions help
to burn calories, leading to a long-term loss of fat mass, and
therefore, a replacement of fat postworkout would be
counterproductive. Instead, the postexercise meal should
consist of mainly carbohydrate- and protein-rich foods.
However, fats add flavor to foods and create a sense of
satiety, and therefore, can be included in small amounts in the
postexercise meal or snack.
Food for Thought 13.2
Nutrition Specifics for Gaining Weight
In this exercise, you are asked to provide and justify
macronutrient intakes you recommend for an athlete
wishing to gain weight.
Are vitamin and mineral needs
different for strength/power
athletes?
The vitamin and mineral needs of strength/power athletes
have not been studied extensively. As with all active
individuals, nutrient needs may be slightly higher than for
sedentary counterparts, but an increased intake of specific
vitamins and minerals may or may not be critical for optimal
strength/power performance. This section reviews several of
the micronutrients that have been suggested to be of
importance, including antioxidants, boron, calcium, chromium,
iron, magnesium, and zinc. As more research develops,
Do strength/power athletes need to
supplement with antioxidant vitamins?
The main antioxidants receiving attention in the exercise
arena are beta-carotene, vitamin C, vitamin E, and selenium.
Antioxidants are touted to combat free radical damage
occurring during and after exercise, including strenuous and
high-intensity exercise. Most of the current research
conducted on the effects of antioxidants and exercise-related
free radical damage has focused on endurance athletes.
Although strength/power athletes may need more of these
nutrients, a specific recommendation cannot be made at this
time. The best option is to consume a variety of antioxidantrich foods such as citrus fruits, dark green and orange
vegetables, nuts, seeds, and Brazil nuts.
Should strength/power athletes supplement
boron intake?
Boron is a nonessential trace mineral found in foods such as
fruits, vegetables, nuts, seeds, and wine. It is readily
absorbed by the body, and the average dietary intake is
estimated to be 1 to 2 milligrams a day. Boron received
considerable attention in the world of strength/power sports
after a study in 1987 reported that people taking boron
supplements had elevated testosterone levels.57 Boron
supplements quickly appeared on the market, claiming the
product could be used as an â€œanabolic steroid alternative.â€
However, a review of the study reveals that the researchersâ€™
conclusions were sorely misinterpreted and taken out of
context. Nielsen and colleagues57 fed a group of
postmenopausal women a boron-deficient diet, and then once
hormone levels had dropped, a boron supplement was
provided. After taking a 3-milligram daily dose of boron, serum
testosterone and estrogen levels returned to normal levels.
This study focused on older women who were not athletes,
and the supplement was intended to correct a deficiency in
the diet. When a study was conducted on young individuals
engaged in the sport of body building, a boron supplement of
2.5 milligrams per day had no effect on testosterone levels,
lean mass, or strength compared with the control group.58 An
RDA has not been established for boron; however, the
estimated daily requirement is thought to be 1 milligram per
day. A UL has been established at 20 milligrams per day for
adults 19 years or older and 17 milligrams per day for
adolescents.59 Low intake of boron, as with all nutrients, can
potentially cause adverse effects; however, supplemental
boron at levels higher than the 20-milligram UL have not been
shown to be beneficial and can have negative effects.
Should strength/power athletes be
Calcium is critical for optimal bone health, muscle
development, and nerve transmission in both men and
women. Unfortunately, many strength/power athletes are not
consuming adequate amounts of daily calcium. This
deficiency is often caused by an avoidance of dairy products
in the quest for a leaner body. Ironically, studies have shown
that higher intakes of calcium can actually aid in weight loss
and body fat loss.60 Much of this research has focused on
overweight individuals placed on calorie-restricted diets with
varied dairy calcium or supplemental calcium intakes. Of
potential interest to strength athletes is the growing evidence
that high dairy calcium intake aids not only increased weight
loss but also higher body fat losses compared with low dairy
or supplemental calcium intakes.61 In addition, dairy products
contain many other essential nutrients for strength/power
athletes, including protein, carbohydrates, vitamin D, and
riboflavin. To promote overall health and a strong body, a
minimum of three to four servings of calcium-rich foods such
as milk, yogurt, calcium-fortified orange juice, green leafy
vegetables, soy milk, and other soy-based dairy alternatives
should be consumed on a daily basis to meet, but not
necessarily to exceed, current recommendations (1,000
milligrams for 19- to 50-year-old men and women).
Is chromium supplementation important for
strength/power athletes?
Chromium is an essential mineral involved in the regulation of
insulin-mediated metabolism of carbohydrates, fats, and
proteins. Some early chromium studies reported positive
changes in body composition,62,63 which have led to a variety
of ergogenic claims, such as increased muscle mass,
decreased fat mass, and enhanced muscular strength.
However, most studies reveal no effect on body composition
or muscular strength after chromium supplementation.64â€“67
Chromium can be easily obtained through the diet in foods
such as mushrooms, prunes, nuts, whole grains, brewerâ€™s
yeast, broccoli, wine, cheese, egg yolks, asparagus, dark
chocolate, and some beers.
iron?
â€œPumping ironâ€ should not be reserved only for the weight
roomâ€”it should also happen in the kitchen. Strength/power
athletes perform a variety of activities that often involve highintensity, weight-bearing movements causing hematuria.
Hematuria is the presence of hemoglobin or myoglobin in the
urine caused by a breakdown of red blood cells (i.e.,
hemolysis) or damage to muscle tissue, respectively.
Hemolysis has been observed in weight lifters as a result of
the mechanical stress of lifting heavy weights. As is the case
for hemoglobin, iron is also essential for the formation of
myoglobin, which stores oxygen inside muscle cells until it is
needed for chemical reactions and muscular contraction.
Sprint swimmers are a unique group of strength/power
athletes that have been found to have low iron levels, even
though a majority of their training is non-weight-bearing. A
study conducted by Brigham and colleagues68 examined 25
female college swimmers for iron status as well as the
effectiveness of iron supplementation during the competitive
season. The baseline tests revealed that 17 swimmers had
depleted iron stores and five swimmers were classified as
anemic. The experimental group consumed 39 milligrams of
iron per day, which was successful in preventing a further
decline in iron status compared with the control group.
However, the authors suggested that a higher dosage might
be indicated to increase iron stores to a healthy range. The
best line of defense is to prevent an iron deficiency from
occurring by ensuring that athletes are consuming plenty of
iron-rich foods daily. If anemia is suspected, a physician
should be consulted before iron supplements are taken.
Strength/power athletes should focus on sources of heme
iron found in foods such as beef, poultry, and fish as well as
nonheme iron, which is found primarily in plant foods such as
soy products, dried fruits, legumes, whole grains, fortified
cereals, and green leafy vegetables. Nonheme ironâ€™s
bioavailability can be enhanced by eating nonheme foods with
either a meat product or a vitamin C source.
Is magnesium supplementation important
for strength/power athletes?
Magnesium has become a popular supplement in the area of
strength/power sports. Because of its role in muscle
contraction and protein synthesis, magnesium
supplementation has been touted to increase muscle mass
and strength. However, only a few studies have demonstrated
an ergogenic effect, and many of the studies have not been
well controlled. Therefore, the verdict is still out on whether
intake of magnesium above the RDA will provide any benefit.
Until the picture becomes clearer, athletes should focus on
consuming magnesium-rich foods such as whole grains,
green leafy vegetables, legumes, nuts, and seafood.
Why is zinc important for strength/power
athletes?
Zinc has a variety of functions in the body, including roles as
an antioxidant, a regulator of growth and development, and a
wound healer. Strength/power athletes benefit from all of
these functions of zinc. Many athletes, especially those on
calorie-restricted diets, may not be consuming adequate
amounts of zinc, and thus it should become a focus of
attention. Zinc is found in a variety of foods, including beef
and other dark meats, fish, eggs, whole grains, wheat germ,
legumes, and dairy products. Zinc supplements are generally
not necessary when an athlete is consuming enough food.
Is multivitamin/mineral supplementation
necessary for strength/power athletes?
It is a common practice for athletes to take a
multivitamin/mineral supplement on a regular basis. Although
this may be a good practice for nutrient â€œinsurance,â€ it may not
be ergogenic. Several research articles have been published
reporting no performance benefit from multivitamin/mineral
supplementation for athletes participating in strength/power
sports.69,70 If an athlete is looking for insurance, it is best to
choose a brand containing no more than 100 to 200% of the
Daily Value for each nutrient to prevent side effects that could
be caused by ingesting large doses of vitamins and minerals.
Gaining the Performance Edge
There is little research to support taking specific vitamins
or minerals to provide an ergogenic benefit to
strength/power athletes, unless an individual is deficient in
a nutrient. Athletes should focus on whole foods first,
ensuring balance, variety, and moderation of all food
groups on a daily basis.
Food for Thought 13.3
Dietary Analysis of a Power Athlete
In this exercise, you will analyze the meal plan of an
athlete whose goal is to gain weight.
Are fluid needs different for
strength/power athletes?
Fluid consumption and hydration are important for all
types of athletes. Muscle tissue is composed mainly
of water, and therefore, when dehydration sets in,
muscular function and performance decline.
Consuming adequate amounts of fluid before,
during, and after strength/power training sessions
and competitions will ensure that an athlete feels
energetic; has the stamina for long, intense
workouts; and recovers well after each session.
What issues are of concern regarding
the fluid intake of strength/power
athletes?
Muscle function and performance will decline when
athletes are in a dehydrated state. To be well
hydrated at the onset of any training session or
competitive event, strength/power athletes should
adhere to fluid consumption recommendations. Note
that fluid losses during exercise are in addition to
daily fluid recommendations. Because of the
frequency, intensity, and duration of strength/power
athletesâ€™ training and competition sessions,
maintaining euhydration is of utmost importance and
should be a dietary focus every day.
One aspect of strength/power sports that often
leads to a restriction of daily fluid intake and
dehydration is the weight-class system. Sports such
as boxing, judo, wrestling, and weight lifting classify
athletes based upon body weight for competitive
events. The goal for these athletes is to maximize
their strength/power relative to their body weight. To
gain an advantage over a competitor, many athletes
will aim for weight reduction immediately prior to a
weigh-in for competition so that they can compete in
a lower weight category. Competing in a lower body
weight category can allow the athlete theoretically to
dominate an athlete who legitimately has a lower
body weight and possibly also less strength and
power. One of the quickest, yet unhealthiest, ways to
cut weight quickly is to dehydrate the body through a
variety of methods such as rubber suits, steam
rooms, and the restriction of fluid intake. The
magnitude of weight loss can range from a couple of
pounds to as high as 9.1 kilograms.71 Athletes may
aim to lose weight on a regular basis, often weekly,
during the competitive season. This continuous
pattern of weight loss, and then often subsequent
weight gain, leads to a pattern of weight cycling,
which not only can be detrimental on a daily/weekly
basis, but also can have a cumulative effect over the
course of an entire season. Some of the negative
effects of severe and intentional dehydration include
poor thermoregulation; loss of electrolytes, thus
increasing the risk for cardiac arrhythmias; and
extra strain on the kidneys, potentially affecting
short-term function. Because of the harmful nature of
these practices, many governing bodies have made
changes in policies and established strict guidelines
to prevent the life-threatening combination of severe
dehydration and high-intensity competition.
The sport of wrestling has received attention for
its efforts to prevent health-related problems caused
by dehydration by changing its policies and
procedures related to establishing a minimum weight
for all athletes. Currently, both the National
Collegiate Athletic Association and the National
Federation of State High School Associations have
minimum weight standards in place.72,73 Minimum
weight for wrestlers is established through body
composition testing to ensure that athletes do not
drop to unhealthy weights and body fat levels. In
addition to weight and body fat testing, all colleges
and many high schools are also measuring hydration
through urine specific gravity, requiring a specific
gravity of â‰¤1.020 before assessing a minimum
weight. Changes to wrestling policies and
procedures are a positive step forward in
safeguarding the athletesâ€™ health and performance.
The established guidelines provide an example to
other sports on the importance of enforcing daily
hydration for athletes.
Although severe dehydration is mainly a health
concern, it should be noted that it can also
significantly decrease strength/power performance.
The impact on performance for very short duration
activities (