Weightlifting and Power Events

Chapter 47
Weightlifting and Power Events
VIC TOR A . R O G O Z K I N
Introduction
The success of athletes in many competitive
sports is determined by the extent to which they
have developed their strength–velocity characteristics: these include strength, speed and power
of muscle function. Peak expression of the functional capability of the athlete requires the
maximum voluntary effort that can be achieved,
and thus depends not only on the characteristics
of the muscle, but also on the initiation of
impulses in the motor centres of the central
nervous system, on the maintenance of high
firing rates in the motor nerves, and on the coordination of the activation of synergistic and
antagonistic muscles. Important muscle characteristics include, in addition to muscle size itself,
the orientation of the muscle fibres, the proportions of the different fibre types present, and the
amount and structure of the connective tissue.
The basics of muscle structure and function
have been reviewed in Chapter 2, and will be
discussed only briefly here. The following
characteristics of muscle are important for the
development of force and power:
1 The maximum muscular effort that can be
achieved is directly proportional to the length of
the individual sarcomeres (Faulkner & White
1990). This cannot be changed with training, but
will be influenced by joint angle, which will in
turn change the length of the muscle. In a whole
muscle, maximum force-generating capacity in
an isometric contraction is largely determined
by cross-sectional area (Maughan et al. 1983).
Adding more sarcomeres in parallel will increase
the maximum force that can be achieved, but
adding more sarcomeres in series will have no
effect on maximum force other than by shifting
the position on the length–tension relationship at
any given joint angle.
2 The maximum velocity of shortening of a
muscle is dependent on the load applied. For
single muscle fibres, the maximum velocity of
shortening, and therefore the maximum speed of
movement, is a function of the myosin adenosine
triphosphatase (ATPase) activity: this determines the rate at which ATP can be used to power
the interactions between actin and myosin. In
fast-contracting (type IIb) muscle fibres, the
maximum velocity of shortening is four times
higher than in slow-contracting (type I) fibres
(Burke & Edgerton 1975).
3 The power that can be developed by a muscle
is a linear function of the maximum ATPase
activity, and thus is closely related to the proportions of the different fibre types present. Muscles
with a high proportion of type II fibres will be
able to achieve higher power outputs than those
where type I fibres predominate. Muscles of elite
sprinters typically contain more than 60% type I
fibres, whereas type I fibres predominate in the
muscles of endurance athletes (Costill et al. 1976).
4 The characteristic relationship between force,
or strength, and velocity referred to above was
described by Hill (1938). Force is greatest during
an isometric activation of the muscle, where the
applied load exceeds the force generating capacity of the muscle and the velocity of shortening
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sport-specific nutrition
is zero: the maximum velocity, in an isolated
muscle or an individual fibre, occurs during
unloaded shortening. This situation cannot be
achieved with the muscle in situ because of the
mass of the limb segments that must be moved
and other biomechanical factors, and maximum
velocity is achieved when the load applied is less
than 20% of the maximum isometric force
that can be generated. The maximum values of
isometric force that can be achieved by human
muscle are approximately 15–30 ¥ 104 N · m2
(Saltin & Gollnick 1982). The maximum force per
unit cross-sectional area of the muscle is not significantly different between the different fibre
types (Faulkner & White 1990).
The known relationships between strength
and velocity of muscle contraction allow identification of the main components of a programme
designed for developing the strength and power
characteristics of an athlete. For development
of the maximum isometric strength, training
should be carried out at forces between 70%
and 100% of the maximum voluntary isometric
strength. To improve performance where high
speeds of movement are required, the force
should not exceed 70% of maximum isometric
strength. Where high rates of power generation
are to be developed, the force applied during
training should be in the range of 40–70% of
maximum isometric force.
Speed–strength sports
The 1996 Olympic Games included a number of
very different types of sport where strength and
speed are primary requirements for the participants (Table 47.1). These include:
• Boxing: open to men only, including 12 weight
categories ranging from 48 kg to over 91 kg.
• Judo: open to men (weight categories from
60 kg to over 80 kg) and women (from 48 to over
72 kg).
Table 47.1 Profile of major championship sports with a high strength component and in which competition is by
weight category.
Wrestling
Boxing
Judo
Weightlifting
Parameters
Male
Male
Female
Male
Female
Weight
classes (kg)
48
51
54
57
60
63.5
67
71
75
81
91
Over 91
60
65
71
78
86
90
Over 90
48
51
56
61
66
72
Over 72
54
59
64
70
76
83
91
99
108
Over 108
46
50
54
59
64
70
76
83
Over 83
Match rules
Three 2-min
rounds
One 5-min bout
Three lifts
One 5-min period
Matches per
day
No more
than one
No more than three
recommended in 2
days
No more than one
No more than
three are
recommended
Weigh-in rules
3 h before
competition
2 h before competition
each day
2 h before competition
Night before
competition
Greco-Roman
and freestyle
48
52
57
62
68
74
82
90
100
130
weightlifting and power events
• Weightlifting: open to men only, with 10
weight classes from 54 to over 108 kg.
• Wrestling: Greco-Roman and freestyle competition, open to men only, with 10 weight classes
from 48 kg to over 130 kg, giving a total of 20
competitions.
In addition, strength and speed are vital components of the sprint events on the track and of
all field events, including long jump, high jump,
triple jump, pole vault, shot, discus, javelin,
hammer throw. In cycling, there are sprint
events on the track for men and women. In the
Winter Olympic competition, speed skating and
bobsleigh (two-man and four-man) also require
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similar characteristics: indeed many speed
skaters are also top class cyclists, and bobsleigh
competitors often compete at 100 m on the track
in the summer. It is clear that sports in this grouping account for the majority of medals awarded
at the Olympic Games.
Non-Olympic sports involving similar characteristics and demands include a variety of
martial arts (karate, Tae Kwondo). Bodybuilding
training follows broadly similar principles,
although the training loads and numbers of
repetitions performed may be somewhat different and the demands of competition are also
different.
(a)
Fig. 47.1 In all weight category
sports, a high power to mass ratio
is essential. Increasing body mass
moves the competitor up into a
higher weight category. (a) Photo
© Allsport; (b) photo © Allsport /
J. Jacobsohn.
(b)
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sport-specific nutrition
The two main characteristics of this group of
sports, therefore, are that, at least in most of
them, competition is open to men and women,
and that, in many, athletes compete in specific
weight categories. This latter fact places particular demands on the athlete, with special
consideration required for training and diet in
preparation for competition.
General nutritional principles
for athletes
The requirements of the athlete for energy and
for individual nutrients are different in different
sports, and will be influenced very much by the
total training load that is carried out (Rogozkin
1978). Body mass is also a major factor, as is
immediately obvious when looking at the
requirements of a light-flyweight boxer (48 kg
weight class), a track athlete, or a wrestler in the
super-heavyweight class (over 130 kg). Even
for athletes with similar body size, however,
the nutritional requirements will vary greatly
depending on the training load: this is set in part
by the demands of the sports but will also vary
within any given event depending on the programme selected by the athlete and coach. Recommended energy intakes for male and female
athletes in different sports are clearly influenced
by many factors, but are likely to be about
14.6–23.0 MJ (3500–5500 kcal) daily for male athletes and 12.5–18.8 MJ (3000–4500 kcal) for female
athletes during periods of hard training
(Rogozkin 1978).
The protein requirement of athletes in different
sports is described in detail in Chapter 10. It
is clear that the requirement for protein will
depend to some extent on the specific nature of
the sport, but will also be very much influenced
by the amount and intensity of the training load,
which will vary at different times of the season.
In Russia, it is generally recommended that the
daily protein intake for athletes in hard training
should be about 1.4–2.0 g · kg–1 body mass
(Rogozkin 1978). The requirement for carbohydrate will be closely related to the power output
required in training and competition, and a daily
carbohydrate intake of 8–10 g · kg–1 would be
considered normal. Depending on the type
of sport, fat intake should be about 1.7–
2.4 g · kg–1 · day–1. These recommendations are
made in absolute amounts related to body
weight rather than as a fraction of total energy
intake, but if the guidelines are followed, this
will give a diet with the following composition:
15–16% of total energy intake from protein,
25–26% from fat and 58–60% from carbohydrate.
The fundamental principles of nutritional
support which have been developed in the
Russian Federation for athletes competing in
strength and power events have been described
in detail by Rogozkin (1993). These are summarized in the following recommendations.
1 The body must be provided with sufficient
energy to meet its needs. For athletes, the energy
requirement will be largely determined by the
total training load. If the energy demand is not
met, it will not be possible to continue with the
same intensity and duration of training.
2 An appropriate nutritional balance among the
various essential nutrients must be maintained.
The proportions of the different macronutrients
and micronutrients necessary to achieve this
balance will depend on the total energy intake
and on the period of preparation relative to competition. Protein intake must provide an appropriate balance of all the essential amino acids,
and the dietary fat must supply all of the essential fatty acids. In addition, the intake of vitamins, minerals and fibre must be adequate for
the athlete’s needs.
3 The choice of foods and nutritional products
that will meet the nutrient requirements will be
different during periods of intensive training,
during the period of preparation for competition,
during competition itself, and during the recovery phase after competition.
4 Several nutrients, mostly vitamins and minerals, play a key role in the activation and regulation of intracellular metabolic processes, and a
deficiency of any of these in the diet will impair
performance during training and competition.
5 Biosynthetic processes involved in tissue
repair and recovery after exercise will be influ-
weightlifting and power events
enced by the hormonal environment: important
factors include the catecholamines, insulin, corticosteroids, growth hormone, cyclic nucleotides
and others. Dietary influences on the metabolic
environment in the recovery phase will influence
the extent of recovery from training and
competition.
6 A varied diet is essential to provide all the
nutrients needed by that athlete in adequate
amounts, but other factors, including especially
those associated with the storage and preparation of foods, will affect the availability of these
nutrients from the diet.
7 The diet must be chosen to include foodstuffs
that will provide all of the essential nutrients, but
care must be taken to ensure that, during periods
when the athlete is training two or three times
per day, the meals are readily digested and
absorbed and do not result in gastrointestinal
disturbances.
8 Where there is a need to increase body mass,
usually in the form of lean tissue, and specifically
in the form of muscle, the diet must contain sufficient protein and other nutrients to ensure that
the increased requirement is met. For athletes
competing in weight category sports, and for
others where a low body mass or a low body fat
content are important, there must be special
attention to the composition of the diet to ensure
that all nutritional requirements are met from the
restricted total energy intake.
9 The diet must be chosen to take account of the
individual physiological, metabolic and anthropometric characteristics of the individual athlete,
and should consider the condition of the athlete’s
digestive system. It must also take personal
tastes and preferences into account.
Only if the diet is selected in the light of these
considerations is it possible to meet all of the
requirements imposed by training and competition and to optimize the athlete’s performance.
Strength training
Muscle, fat and bone are the three major structural components that determine the body shape
and size of the individual. Body build is to a large
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degree genetically determined, as is the ability to
achieve success in sport. Specific types of physical training can modify the expression of the
individual’s genetic endowment, resulting in
changes in body composition. Weight training is
effective when the aim is to increase muscle
mass, whereas endurance training can alter
energy balance and reduce fat mass. An appropriate weight-training regimen, however, will
also be effective in reducing body fat content if
combined with a suitable diet.
There are several categories of strength exercise that can be included in a weight training
programme: these include isometric (static) contractions, which are not truly contractions, as the
muscle is not allowed to shorten during activation and the angle of the limb is fixed. Because of
stretching of the elastic components, however,
there will be some shortening of individual sarcomeres. Isokinetic exercise involves shortening
of the muscle at a fixed velocity, and requires
special apparatus to keep the velocity of shortening constant while measuring the applied force.
Isotonic exercise, in which a constant load is
applied to the muscle is the type of training
most familiar to and popular with coaches and
athletes (Fahey 1986). The applied load may be
in the form of free weights or a resistance machine. Isotonic strength-training techniques may
include constant or variable load, and may
involve lengthening of the muscle (eccentric activation) as well as the more normal shortening
(concentric activation) when the load is applied.
Plyometric and speed loading techniques may
also be included in a strength programme.
It has been shown that greater increases in
strength can be achieved following a programme
of maximum-force concentric and eccentric activation than when concentric activation alone
is used (Fahey 1986). The available evidence
suggests that eccentric activity results in some
degree of damage to the muscle, involving disruption of the muscle membrane and possibly
also some disruption of the contractile components, and the subsequent repair process seems
to be important for the increase in the size of
muscle fibres that results from a strength training
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sport-specific nutrition
programme (Faulkner & White 1990). Strength
training with high loads leads to an increase in
the cross-sectional area of the muscle without
any appreciable change in muscle length, and
changes in cross-sectional area of the muscle can
be used as an index of the gain in muscle mass.
Both type I and type II fibres increase in size in
response to this type of training stimulus, and
increases in cross-sectional area of 39% for type I
fibres and 31% for type II fibres have been
reported after a programme of heavy resistance
exercise (MacDougall et al. 1980). Increases in
force-generating capacity after strength training
may be large (30–40%) in the early stages of a
training programme, and are invariably greater
than the increase in cross-sectional area
(Maughan 1984). Some of the increase in muscle
strength is therefore likely to be the result of
changes in the muscle recruitment pattern and in
neural drive. In pennate muscles, where the individual fibres lie at an angle to the long axis of the
muscle, increases in the size of the individual
fibres will result in an increase in the angle of
pennation, which will have the effect of decreasing the force relative to the anatomical crosssectional area (Maughan 1984).
Release of a variety of hormones is stimulated
during and after high resistance training: these
include growth hormone, testosterone, catecholamines and cortisol (Sutton et al. 1990). The
release of these hormones will be influenced by
the intensity of training, the length of rest periods
allowed, and the level of training of the athlete.
The response to training is specific to the muscle,
so there must be a change in the sensitivity of the
active muscle to the circulating hormones and
growth factors so that changes in the systemic
concentration results in specific changes in
protein synthesis. This may involve a change in
receptor number or sensitivity and/or release of
local growth factors (including insulin-like
growth factor) in the working muscle in response
to hormonal stimulation.
Increases in muscle strength and muscle
hypertrophy have been shown to be greater after
prolonged fatiguing contractions than after
short, intermittent contractions (Schott et al.
1995). The authors speculated that the enhanced
response after fatiguing contractions indicated
an involvement of changes in intracellular
metabolite levels and pH in determining the
response of the muscle.
In addition to the changes in muscle size and
strength, weight training will have a significant
effect on bone mass. Peak bone mass, which is
normally reached in the third decade of life, can
be increased by any form of weight-bearing exercise, and will help to protect the skeleton against
the stresses imposed on it. These processes are
described in detail in Chapter 23.
As the muscle becomes stronger with training
and the load that can be applied increases, so the
stimulus for new bone formation should also
be increased to a degree consistent with the
imposed load or relative intensity of the exercise.
The imposed load is more important for determining the response of bone than the number of
loading cycles completed. Progressive resistance
training should therefore allow the bone mass to
increase until it reaches the genetically determined peak bone mass. Given the greater length
of time required for new bone formation relative
to the adaptation of skeletal muscle, which is
apparent within a few days of training beginning, changes in bone mass require long-term
adherence to a training programme that will
effectively load the skeleton.
Training diet
The adaptive changes that occur in the various
organs and tissues of the athlete in response to
the training load occur in a phasic manner. The
acute responses to a single bout of exercise are
translated into a permanent (at least as long as
the training persists) condition by a series of
events that may be described as fatigue, restoration and supercompensation. The adaptations
which occur in response to training result in an
increased capacity for force generation, power
output or endurance, depending on the type of
training. This will be manifested during the
weightlifting and power events
effort itself, but there must be, during the postexercise period, an altered gene expression to
cause an enhanced synthesis of specific proteins.
To achieve these aims during the training
period, athletes normally follow a training programme containing microcycles lasting 3–5 days.
Each training microcycle is constructed to allow
adaptation of all of the different functions which
respond to the specific training undertaken.
Complete adaptation in response to this type of
training usually appears after three to five repetitions of the cycle (Lamb 1984).
The diet consumed by the athlete during this
training phase should be designed to supply the
necessary energy and nutrients in order to maximize the efficiency of the training process. Preparation of the diet requires a knowledge of the
total energy demand, but also some understanding of the specific character of the training programme at any given time. Energy expenditure
of strength and power athletes during periods of
heavy training is typically about 14.6–18.8 MJ
(3500–4500 kcal), depending on body weight,
and the preparation of a balanced diet is not difficult to achieve. However, it appears that at some
times in the training cycle of these athletes, there
is a need for an increase in the dietary protein
intake if muscular development is to occur. To
meet the protein requirement of weightlifters,
sprinters and throwers, for example, it is recommended that the daily protein intake should be
1.4–2.0 g · kg–1 body mass (Rogozkin 1993). This is
slightly higher than the intake of 1.4–1.7 g · kg–1
recommended by Lemon (1991). It is not only the
total protein intake that is important, but also the
content and balance of the essential amino acids,
and the proteins in meat, fish and dairy produce
have a higher biological value than those in other
foods. Dairy products have a high content of the
sulphur-containing amino acid methionine,
which is indispensable for the synthesis of
muscle protein (Williams 1976).
The fat intake for athletes from these sports
should be approximately 2 g · kg–1 · day–1, and a
significant part of this will be provided by the
protein-rich foods in the diet, especially meat
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and dairy produce. Vegetable oils, however,
including sunflower seed, corn and nut oils, are
valuable sources of the essential polyunsaturated fats, which may comprise as much as
50–60% of their total fat content. Dietary fat is
also important in ensuring an adequate supply
and uptake of the fat-soluble vitamins A, D and
E. A carbohydrate intake of 8–10 g · kg–1 · day–1
should be sufficient to meet the needs of the
organism even during the heaviest training.
The requirements of the strength athlete for
vitamins and minerals have been identified, and
the recommended intakes are shown in Table
47.2 (Rogozkin 1993).
The following general and specific recommendations are made.
1 The energy requirement for the athlete in training should be completely satisfied from nonprotein sources (carbohydrate and fat).
2 The diet should contain an increased amount
(15–20%) of energy from protein, consisting of
biologically valuable and easily assimilated proteins from various sources, including meat, fish,
milk and eggs.
3 Meals with a high protein content should be
eaten no less than five times per day.
4 There must be optimal conditions for the
assimilation of the protein components of foods.
After training, meat should be taken together
with vegetables, and during the intervals
Table 47.2 Recommended daily intakes of vitamins
and minerals for athletes during periods of intensive
strength training.
Vitamins
C
B1
B2
B3
B6
B9
B12
PP
A
E
Minerals
175–200 mg
2.5–4.0 mg
4.0–5.5 mg
20 mg
7–10 mg
0.5–0.6 mg
4–9 mg
25–45 mg
2.8–3.8 mg
20–30 mg
Phosphorus
Calcium
Potassium
Magnesium
Iron
Zinc
Iodine
Chromium
2.5–3.0 g
2.0–2.4 g
5.0 –6.0 g
0.5–0.7 g
25–35 mg
25–35 mg
150–200 mg
10–15 mg
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sport-specific nutrition
between training sessions, special protein supplements should be taken.
5 It is necessary to ensure an adequate intake of
vitamins (B1, B2, B6, C and PP) which promote
protein synthesis and the accumulation of
muscle mass.
Careful attention to diet is necessary during
periods of intensive weight training in order to
create the appropriate metabolic environment to
allow increases in muscle mass to occur.
Diet and weight control
Restriction of energy intake sufficient to result in
a negative energy balance is an essential part
of any successful weight-control programme
(Williams 1976). Most fad diets that promise
rapid loss of body weight stress weight loss
rather than fat loss, and may seriously affect the
athlete’s performance because loss of lean tissue
is likely to account for much of the loss in weight.
These diets are often unpalatable and unhealthy,
and do not represent an eating pattern that
would be possible to sustain on a long-term
basis. A rebound gain of the lost weight is almost
inevitable. The goal of the dietary programme
when weight loss is required should be a loss of
body fat followed by maintenance of that loss.
Many popular diets promote a low carbohydrate intake, and these diets may be successful in
causing large weight losses, perhaps as much as
5–10 kg in a few weeks. However, a diet that is
low in carbohydrate will result in depletion of
the liver and muscle glycogen stores and in a loss
of water from tissues. Although the weight loss
seems impressive, there may be little loss of body
fat. Additionally, glycogen depletion greatly
diminishes exercise capacity, leading to a
decreased exercise level, which in turn means a
decreased level of energy expenditure. Periods
of low exercise levels in combination with
restricted energy intake result in a loss of muscle
tissue.
A successful weight-loss programme requires
a negative energy balance. Given that the energy
content of 0.45 kg of fat is about 14.7 MJ (3500
kcal), which is as much as most athletes expend
in day, it is clearly impossible to lose more than a
few pounds of fat in a week. Empirical evidence
suggests that, if weight is lost at a faster rate, the
loss must come increasingly from loss of muscle
mass. Diets that promise large decreases in fat in
a short time are misleading: they are potentially
dangerous and will impair performance.
Weight loss and making weight
The aim of all weight-loss programmes should
be to restrict food intake so that the body’s fat
reserve is gradually reduced while the normal
functions of the body are maintained. The only
successful approach is to reduce energy intake
while ensuring that the nutrient density, and in
particular the carbohydrate content, is kept high.
The reducing diet will therefore be achieved by
restricting fat, rather than carbohydrate, intake.
Foods should be chosen to provide not only carbohydrate, which should be present mostly in
the form of complex carbohydrates, but also vitamins, minerals and trace elements in adequate
amounts, rather than simply being high in fibre.
All visible fat should be removed from meat, and
low-fat foods should be substituted for high-fat
alternatives where these are available. If the diet
is already very low in fat, the only available
option is to reduce the overall amount of food
being eaten.
Making weight is a different situation from a
gradual weight-loss programme. This situation
arises when athletes have to prepare to compete
in a particular weight category. Most athletes
participating in sports with specific weight categories, including boxing, judo, wrestling and
weightlifting, compete in a class that is 5–10%
below their usual weight. Typical weight reduction techniques used to induce large weight
losses in a short time include dietary restriction,
fluid restriction, dehydration through exercise in
the heat or in a rubber suit, or sitting or exercising
in a sauna or steam room. Less commonly used
techniques include the use of diuretics and laxatives, vomiting and spitting.
Athletes will commonly lose weight rapidly in
the last few days before competition (3–4 kg in
weightlifting and power events
the space of 3–4 days) by a combination of sweating and severe restriction of food and fluid
intake. This practice of making weight may be
repeated very often in a competitive season, as
the lost weight is quickly regained. A more
gradual weight loss (3–4 kg over 3–4 weeks)
achieved by a more modest restriction of energy
intake and increased energy expenditure would
probably allow a better hydration state to be
maintained. Prolonged dietary restriction,
however, would inevitably involve restriction of
protein and carbohydrate intake, and might lead
to some loss of body proteins and glycogen
stores. Although dehydration has a much
smaller impact on high-intensity exercise than on
endurance activities, and does not seem to
compromise muscle strength or performance in
events lasting less than 30 s, some reduction in
function may occur (Sawka & Pandolf 1990).
Dehydration is better tolerated by trained
athletes than by sedentary individuals, with
less impact on thermoregulation and exercise
performance (Sawka & Pandolf 1990). The
trained person has an increased body water
reserve, and may be able to tolerate a fluid deficit
of up to 5% of body mass without a significant
detrimental effect on some aspects of physiological function (Rehrer 1991).
Athletes should be encouraged to maintain
a relatively stable body weight and to lose
unwanted fat gradually. The practical experience
of athletes and coaches, however, indicates that
the most successful performers often undergo
severe weight-loss regimens in the few days
before competition. The use of diuretics, and
competition after their use, is to be discouraged.
Not only does this impair performance, but also
poses a health risk.
Gaining weight
A high body mass is an advantage in many
sports, including the throwing events in athletics, and the top weight categories in weightlifting, wrestling and judo. If too much of this
weight is made up of fat, however, performance
will suffer. The principles of weight gain are the
629
same as those for weight loss: a positive energy
balance will result in weight gain, and a negative
energy balance will result in weight loss. Athletes
who are seeking to gain weight should strive to
ensure that as much as possible of the gain is in
the form of lean tissue. This can be achieved most
effectively through a vigorous weight-training
programme that stresses the large muscle groups
in the legs, hips, shoulders, arms and chest.
Increases in muscle mass occur only slowly, and
may take many years to be fully realized, but this
is preferable to the increase in body fat that is
quickly added by the use of high-energy weightgain supplements.
Eating a high-protein diet will not in itself
result in an increase in muscle mass (Lemon
1991). Any protein consumed in excess of the
body’s requirement will simply be used as a fuel
for oxidative metabolism, and the excess nitrogen will be excreted. The common practice of
eating large amounts of meat, dairy produce and
eggs is expensive, and is potentially detrimental
to the athlete’s health and performance. Abnormal eating habits established during the years of
training are not easily altered in later life, and
consumption of a relatively high fat diet, which
almost invariably accompanies a high intake of
these foods, may lead to an increased risk of cardiovascular disease. In addition, if the intake of
protein and fat is too high, there will be little
room left in the diet for high-carbohydrate foods.
Without an adequate dietary carbohydrate
intake, the athlete is unlikely to be able to train to
full potential and will be unable to maximize the
benefits that accrue from consistent intensive
training.
Many weightlifters and bodybuilders use specific amino acid supplements in an attempt to
stimulate output of growth hormone and insulin,
as both of these hormones are involved in the
stimulation of protein synthesis and thus in the
processes of muscle growth and repair. In a carefully controlled trial, however, supplementation
with the amino acids that are purported to be
effective at a dosage equal to that commonly
used by power athletes (1 g arginine, 1 g
ornithine and 1 g lysine, twice daily), had no
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sport-specific nutrition
effect on serum growth hormone or insulin concentrations (Fogelholm et al. 1993). There seems
to be no substantial evidence to support the use
of these supplements.
The addition of medium-chain triglycerides,
which include fatty acids with a carbon chain
6–12 atoms long, to the diet of athletes is a new
phenomenon (Manore et al. 1993). Medium-chain
triglycerides are metabolized differently from
longer chain fatty acids. They are absorbed
rapidly in the gut and transported via the portal
vein to the liver, rather than through the lymphatic system in the form of chylomicrons. As
with longer chain fatty acids, oxidation occurs in
the mitochondria, but carnitine is not required
for transport across the mitochondrial membrane. They are rapidly oxidized after ingestion.
The use of medium-chain triglycerides is
becoming popular with athletes, especially
bodybuilders, because they are energy dense
(35.3 kJ · g–1, 8.4 kcal · g–1), providing twice the
energy of carbohydrate on a weight basis. A
single dose of 25–30 g of medium-chain triglycerides does not cause any gastrointestinal
problems, but some symptoms may occur with
higher doses (Berning 1996). They are, however,
relatively expensive. Also, ingestion of large
amounts will stimulate ketone body formation if
not consumed with an adequate amount of carbohydrate, and have a strong thermogenic effect.
Creatine supplementation in an appropriate
dose can provide improved performance for athletes in explosive events: these include all events
lasting from a few seconds to a few minutes. The
effects and use of creatine are described fully in
Chapter 27. One commonly reported side-effect
is a gain in weight of 1–2 kg within a week of
beginning supplementation. Most of this extra
weight is accounted for by water, but this may
have implications for athletes in weight category
sports.
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