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Copyright © by ESPEN LLL Programme 2015 1
Nutrition and Sport Topic 37
Module 37.3
Nutrition for Strength and Power Sports
Nada Rotovnik Kozjek,
MD, PhD, anaesthesiologist
Institute of Oncology, Ljubljana, 1000, Slovenia
Slovenian Olympic Committee, Ljubljana, 1000, Slovenia
Peter Soeters,
MD, PhD, emeritus professor of surgery
Maastricht University Medical Center, Maastricht, 6200, Netherlands
Learning Objectives
To present basic definitions and muscle physiology of power and strength sports;
To explain substrate use in power and strength sports;
To understand the complexity of nutritional support for training and competition in
strength and power sports;
To use existing recommendations in clinical sport nutrition for planning specific
nutritional strategies in power and strength sports;
To safely and effectively use performance-enhancing substances on the basis of current
sport nutrition guidelines.
Contents
1. Introduction
2. Basic considerations for power and strength sports
2.1. Definition of power and strength sports
2.2 Structural basis for muscle training and muscle fibre metabolism
2.3 Summary
3. Nutritional support
3.1 Periodization of nutritional support
3.2 Energy and nutrient intake recommendations for strength and power sports
3.2.1 Carbohydrate intake
3.2.2 Protein intake
3.2.3 Fat intake
3.2.4 Water
3.3 Summary of nutritional strategies to optimize recovery
3.4 Summary
4. Performance enhancing substances
4.1 Caffeine
4.2 Creatine monohydrate
4.3 β-alanine
4.4 Sodium bicarbonate
4.5 β-hydroxy-β-methylbutyrate
4.7 Summary
5. References
Copyright © by ESPEN LLL Programme 2015 2
Key Messages
• The metabolic response to exercise is dictated by energy demand and duration of
physical activity and substantially influences the ability to produce muscle power;
• Training for strength, power or speed causes specific changes in the immediate (ATP,
PC) and short-term (glycolytic) energy system, as well as increases in the muscle
buffering capacity improving strength and/or sprinting performance;
• The intake of energy and macronutrients must be personalized according to athletes’
training periodization and individual responses to specific training stimuli and
characteristics;
• Ensuring strategic energy and nutrient availability at critical training points is important
for optimal training, regeneration and competitive performance but is also essential for
immune system protection and injury prevention, and a prevention of over-reaching
and over training;
The benefit of using approved performance enhancing substances should be individually
checked and adjusted to the specific athlete’s needs.
Copyright © by ESPEN LLL Programme 2015 3
1. Introduction
Scientific findings about the underlying mechanisms of various physiological phenomena
induced by exercise, including the recovery process, are the basis for nutritional strategies
adjusted to the specific demands of every athlete. The strategically adjusted consumption of
key nutrients, depending on the specific needs of an individual, aims to enhance athletic
performance and regeneration, thus allowing an athlete to reach his or her full genetic
potential and benefit from physical activities which alternate in duration and intensity (1).
An appropriate strategy for nutritional support in power and strength sports is developed as a
combination of general recommendations from the field of clinical sports nutrition for energy
intake, amounts and composition of nutrients and fluid intake, and recommendations specific
for the type of sport and for different phases in the training process. The dietary intake of food
has immediate as well as long-term effects on the athlete’s well-being, health, and
performance. The diet directly affects the key elements of athletic performance, and should be
prescribed in accordance with other factors that could potentially influence food composition,
such as social and cultural influences and the personality of the athlete.
2. Basic Considerations for Power and Strength Sports
The term exercise is defined as any activity involving force and power generation by
coordinated activation of the appropriate skeletal muscles (2). Power is defined as the amount
of work performed per unit of time (2). It reflects the ability to exert maximum muscular
contraction instantly or in an explosive burst of movements. The two components of power are
strength and speed (e.g. jumping or a sprint start). From the energetic, and also nutritional,
point of view, it is important to understand that power is the rate at which work can be
performed or the rate of the transformation of metabolic potential energy to work and/or heat.
Strength is defined as the ability to carry out work against the highest resistance. Muscle
strength represents the maximal force generated by muscle contracting against a load (e.g.
holding or restraining an object or person) (3). A typical example of muscle strength is the
force and velocity of the motion with which the weightlifter acts on the barbell.
The assessment and quantification of these physical abilities is described by the use of
International System of Measurements (SI) for force (Newton); energy, work and heat
(Joules), torque (Newton-meters) and power (Watts).
Power in sport can be determined for a single body movement, a series of movements, or a
large number of repetitive movements. It can be determined instantaneously at any point in a
movement, or averaged for any portion of a movement or bout of exercise (3). In complex
human motions, the maximum output of mechanical power is reached with approximately 50%
of maximum force and velocity of a given athlete (4).
Optimal power output demands effective muscle coordination and mechanical efficiency of limb
movement, meaning that optimal sports performance requires the consideration of both
mechanical (e.g. best gear ratio in cycling) and biomechanical factors (e.g. step length in
running, stroke length in swimming). The best choice of gear ratio, step or stroke length etc. is
the one that allows muscles to contract with optimum speed and optimum force, which results
in maximum mechanical muscle power. In complex motor tasks, the resulting power is
influenced not only by the qualities of individual muscles and tendons, but also by muscle
coordination, the relationship between muscles and external forces, and by activity of the
nervous system (5).
Copyright © by ESPEN LLL Programme 2015 4
2.1. Definition of Power and Strength Sports
Intense exercise events in which high power output is required for success are considered as
power sports. Typical power sports are medium-distance running, track cycling, Olympic
rowing, canoeing/kayaking, and swimming (6).
The term strength sports covers the type of activities where maximal force of torque can be
developed by muscles performing a particular joint movement (7). Muscles may contract
maximally during isometric, concentric, eccentric actions or stretch-shortening cycles. The
ability to generate explosive muscle power and strength is important for sports such as
weightlifting, sprinting, throwing events and bodybuilding (8).
Training methods to increase maximal muscle force (strength) and power are developed
employing resistance exercise programs. These programs make use of very high opposing
force (routinely termed resistance), the training includes lifting weights or otherwise increasing
the resistance against which is worked. Power and strength athletes incorporate resistance
exercise programs in their yearly training plan. Resistance training is frequently included in the
training of endurance athletes too (9). It was shown that the focus on more explosive type of
lifting (Olympic lifting) results in better power and strength gain in comparison with more
traditional strength-based lifting mainly because of inducing neural adaptation (10, 11).
The focus of this module is to present nutritional recommendations for athletes involved in
events lasting up to 10 minutes. However, elements of strength and power sports are included
also in games and fighting sports (e.g. tennis, boxing) where specific cyclic movements are
interrupted with acyclic movements such as jumps, throws and hits.
2.2. Structural Basis for Muscle Training and Muscle Fibre Metabolism
The metabolic response to exercise is dictated by energy demand and duration of physical
activity and it substantially influences the ability to produce muscle power. Training for
strength, power or speed causes specific changes in the immediate (adenosine triphosphate -
ATP, creatine phosphate - CP) and short-term (glycolytic) energy system, as well as increases
in muscle buffering capacity, which is shown by improvements in performance (12, 13). The
amount of CP can be increased with ingestion of creatine (14). Glycolytic rate can be
significantly increased with high intensity or interval type of training. Increased acid buffering
capacity is shown in a muscle cell and on a systemic level. Buffering capacity can be
augmented with sports supplements (sodium bicarbonate, β-alanine) (15).
Several months of resistance training causes hypertrophy of muscle fibres and increases
muscle cross sectional area, thus increasing maximum power output (16).
The pattern of fibre metabolism and recruitment is reflected in the metabolic response (13,
17). This also reflects individual characteristics (genetics, training status). At low intensity
effort, most of the glycogen used is in type 1 slow twitch fibres. At high intensities, type 2
fibres account for most of the glycogen used, even though type 1 fibres are active. Type 2b/x
fibres have a high glycolytic and oxidative capacity and ensure the necessary amount of ATP
during activity of up to 1 min. Intense activation of these metabolic systems also releases a
large amount of lactate, which is then accumulated by sportsmen during high-intensity effort.
The longer such intensive effort is maintained, the lower the relative maximal uses of oxygen
and the larger the fraction of energy contributed by the decomposition of substrates for
oxidative phosphorylation. When the intensity of effort is lowered, type 1 fibres contribution to
metabolic energy support increases.
Copyright © by ESPEN LLL Programme 2015 5
2.3. Summary
In complex human motions, maximum output of mechanical power is reached with
approximately 50 % of maximum force and velocity for a given athlete. The time frame for
typical power sports is up to 10 minutes and is represented with sports activities such as
middle-distance running, track cycling, rowing, canoeing/kayaking, and swimming. The term
strength sports covers the type of activities where maximal force or torque can be developed
by muscles performing particular joint movements. Because of the number of variables or
conditions involved, the strength of a muscle or muscle group is defined as the maximal force
generated at a specified or determined velocity. Training plans to increase maximal force
production (strength) and maximal power of the muscle are developed through resistance
exercise programs. Training for strength, power, or speed causes specific changes in the
immediate (ATP, PC) and short-term (glycolytic) energy systems, and increases the muscle
buffering capacity, resulting in improvements in strength or sprinting performance.
3. Nutritional Support
The nutritional support for power and strength athletes is a complex issue and aims:
to provide metabolic fuels (nutrients) that will generate energy in the right quantity and
at the right time for specific sport training;
to provide energy for competition;
to support recovery from training and competition;
to promote training adaptations, including muscle hypertrophy;
to help maintain well-being and health (6, 8, 18, 19).
The energy and nutritional needs of an athlete are determined by the metabolic characteristics
of the individual and the metabolic requirement of the training load (duration, intensity and
type of physical activity or sport). For the nutritional evaluation of an athlete the nutritional
recommendations for energy and nutrient intake, as well as for fluid replacement are
established, taking into account specific requirements of the physical activity or sport are
established. Specific nutritional recommendations were discussed in several recently published
papers (6, 8, 20-25).
The total nutritional intake – daily, weekly etc. – as well as the nutritional intake during
physical effort must be adapted to energy needs, which correspond to the metabolic response
of sport-specific training. Table 1 presents sport-specific energy consumption and its profile
for the aerobic and anaerobic energy system contributions during a high-speed treadmill
exercise that simulated 200-, 400-, 800-, and 1500-m track running events. Spencer and
Gastin investigated the estimated contribution of muscle cell energy systems and found that
the relative contribution of the aerobic energy system during track running events is
considerable and greater than was traditionally thought (26). The comparative values for
energy provision in other power sports are also shown in Table 1.
Copyright © by ESPEN LLL Programme 2015 6
Table 1
Energy sources in power sports (adapted from 6).
Resistance training requires a high rate of energy generation and is basically an anaerobic
exercise. The contribution of energy systems (phosphagen, glycolytic) depends on the relative
power output, the work-to-rest ratio, and the muscle blood flow (27). Fatigue during resistance
exercise has a multifactorial genesis. Metabolic fatigue during the earlier part of the workout is
partially due to phosphagen depletion and mild intramuscular acidosis, and is followed by
systemic acidosis and impaired energy production from glycogenolysis (28). Neuromuscular
dysfunction is an important additional cause of fatigue (29).
3.1 Periodization of Nutritional Support
For optimal performance in power and strength sports, training is necessary to improve and
develop metabolic energy pathways for substrates: creatine, glucose and fats in different
proportions. Improving the buffer capacity of the muscle cell also contributes to more
successful training and development of a greater capacity. Therefore, a training plan in power
sports involves different training modalities, which enable the development of these metabolic
paths. In practice, it is important to keep in mind that the proportions of various energy
sources depend primarily on the duration and intensity of physical activity, and to
appropriately adapt nutritional strategies to the different types of training that are included in
the training plan. To use the general recommendations for sports nutrition it is thus necessary
to understand the basic concepts of training planning.
For their training plan, sportsmen should take into account the concept of training
periodization. Training periodization is defined as a collection of workouts with a specific
purpose, where training sessions are arranged so as to induce maximal adaptations in all
metabolic systems that are required for the specific sport. An annual training plan or macro-
cycle, is planned to peak at the important competition of the year. In general there are four
phases in the macro-cycle: general preparation, specific preparation, competitive period, and
transition. Macro-cycles are composed of micro-cycles, which typically last a week. Each micro-
cycle is planned based on its position in the overall macro-cycle. A micro-cycle is also defined
as a number of training sessions built around a given combination of acute programme
variables, which include progression as well as alternating effort (heavy vs. light days). The
length of a micro-cycle should correspond to the number of workouts in the week (30, 31).
Event time
range () Event example
Approx.%
VO2max
% of energy contribution
Phosphagen Anaerobic Oxidative
breakdown glycolysis phosporylation
0.5 to 1min
400 m running, cycling time
trial (500 m-1km)
100 m swimming disciplines
150 10 47-60 30-42
1.5 to 2 min
800 m running;
200 m swimming disciplines
500 m canoe/kayak disciplines
113-130 5 29-45 50-66
3 to 5 min
1500 m running;
cycling pursuit;
400 m swimming disciplines;
1000 m canoe/kayak disciplines
103-115 2 14-28 70-84
5-8 min
3000 m running;
800 m swimming disciplines;
2000m rowing
98-102 <1 10-12 88-90
Copyright © by ESPEN LLL Programme 2015 7
On average, power athletes undertake 9-14 training sessions per week (6). The duration of
workouts is between about 30 minutes and 3 hours (6). The training typically includes
resistance and plyometric/neuromuscular training several times per week. The workout stimuli,
and consequently the metabolic demands of each training cycle, differ depending on the
intensity and amount of training, so that the sportsman needs a periodized and personalized
nutritional support. In Table 2, a schematic overview of training and nutritional periodization
during an annual training cycle is presented.
Table 2
Nutritional periodization during the annual training cycle (adapted from 6)
Training
phase
General preparation Specific preparation Taper /
Competition
Transition
Training/
competition
goal
High training volume
(5-12 h/week)
Moderate training
volume
(4-10+ h/week)
Low training volume
(3-10+ h/week)
Very low training
volume
Aerobic energy system
development
Lower training intensity
Anaerobic system
development
Race specific pace
Training competitions
Race specific
intensities
Neuromuscular power
Very low intensity
Mixed training modalities Specialized training/
altitude camps
Competitions Recovery training
to prevent over-
reaching
Resistance
training
periodization
High-volume, high-force,
low velocity training
More explosive, lower
force, low repetition
training
Competitions
Nutritional
goals
Daily target
(g/kg BW/d)
CHO**
PRO***
fat
High energy intake to
support training
50-70kcal/kg/d
Nutrition to support high
intensity training
42-64 kcal/kg/d
Nutrition to support
high intensity racing
40-60 kcal/kg/d
Nutrition for
active individuals
28-42 kcal/kg/d
Recovery after training Specific
support/recovery for key
training sessions
Support recovery
after races
To reach optimal body
composition
Preparing specific
nutritional strategy for
competition period
Avoiding weight gain
with lower training
volume
Minor weight gain
6-12 (4-7)*
1.5-1.7
1.5-2
6–10 (4-7)*
1.5-1.7
1-1.5
6–10 (4-7)*
1.5-1.7
0.8-1.2
4-6
0.8-1.2
1–1.2
*Carbohydrate intakes for strength athletes
** CHO, carbohydrate
***PRO, protein
3.2. Energy and Nutrient Intake Recommendations for Strength and Power
Sports
Strength and power athletes form an extremely diverse group. In general, the energy intake
for strength athletes and a majority of power athletes is not a concern as many of them strive
to gain or maintain higher than normal lean body mass. However, this group of athletes also
includes those who restrict their energy intake in an attempt to maintain their weight within a
specific competition weight class (Olympic weight lifting, judo), and those who compete in
sports with an aesthetic or image element (gymnastics, bodybuilding). As the optimal balance
between body composition and body mass is in many sports an important parameter for
Copyright © by ESPEN LLL Programme 2015 8
success, the appropriate nutritional strategies during the preparation period should be adapted
to the goal of optimal body composition of the individual sportsman.
The starting point for a nutritional strategy for power sports is the general nutritional
recommendations for the energy and nutritional intake of endurance athletes (see Section 3)
(32, 33). However, basic knowledge of the metabolic demands of different types of physical
activities is necessary for planning a nutritional strategy for power and strength athletes. In
this way the recommendations can be adapted to the type of exercise, its duration and
intensity, environmental conditions and specific characteristics (Table 2, Table 3) (6, 8). It
seems that taller and more muscular individuals have lower total energy consumption and
lower energy consumption at rest (34). A personalized approach is here even more important:
when the energy intake is estimated correctly, given the body composition, this intake is lower
than what is recommended for strength athletes (8, 23). When estimating the energy intake, it
is therefore important to prioritize the timing of energy intake in relation to a training session,
rather than simply to comply with the general nutritional guidelines. With a suitable nutritional
strategy, it is necessary to ensure appropriate energy intake that will allow the sportsman to
carry out the planned amount and intensity of training (35).
It has been shown in power and strength sports that female athletes have a substantially lower
energy intake than males (35). Female intake is 40 kcal/kg BW, while male intake is 55
kcal/kg BW. The reason for this substantial difference in energy volume may be due to the
differences in the amount and intensity of training between males and females and/or greater
under-reporting by females. The energy intake in females, but also in males, should be
monitored carefully because of a high risk of hormonal disturbances resulting from a too low
energy intake (33). An additional important reason for monitoring energy intake is the
maintenance of a competitive body weight and enhancement of power-to-weight ratio. This is
achieved with skeletal muscle hypertrophy and/or by maintaining low body fat levels, which
can be physiologically and psychologically very demanding. It also increases the risk of
developing eating disorders.
For monitoring body weight it is useful to follow body composition during different nutritional
strategies and not only to perform regular weight measurements.
During the transitional period the maintenance of optimal body weight is less important, and
due to less or no training the energy intake is reduced towards nutritional recommendations
for the general public.
3.2.1. Carbohydrate Intake
Research data show that sufficient intake of carbohydrates is necessary for optimal sports
performance in strength and power sports. In high-intensity effort, which lasts few seconds to
10 minutes, anaerobic and oxidative metabolism of carbohydrates provides the majority of
ATP.
High intensity exercise considerably depletes glycogen stores. Thirty seconds of maximal
running decreases muscle glycogen by 25 %, and experimental data about glycogen depletion
in single resistance training show a reduction of glycogen stores by as much as 24-40% (27,
28, 36). The greatest reductions in glycogen stores are observed with higher repetitions-
moderate load resistance training and affects mainly type 2 fibres. This type of training is used
mainly to reach muscle hypertrophy. Resistance training is a frequent component of overall
training programmes and has a considerable impact on glycogen storage in working muscles.
Glycogen resynthesis after resistance training can also be impaired by skeletal muscle damage,
Copyright © by ESPEN LLL Programme 2015 9
which accompanies resistance training. Low glycogen availability has also been shown to
mediate muscle protein breakdown and in this way to diminish the efficiency of resistance
training (37). It has been reported that nitrogen losses were more than doubled following a
bout of exercise in a glycogen-depleted versus a glycogen-loaded state (38). Low glycogen
stores result in reduced high-intensity performance in several experimental protocols (39).
On the other hand, sufficient glycogen stores improve exercise capacity during high-intensity
exercise, although this effect is less consistent (8, 40).
Daily carbohydrate intake
Nutritional surveys about daily intake of carbohydrates in power and strength group of athletes
have shown highly variable numbers in the range of 3-7 g/kg BW/day (8). A personalized
approach is proposed, which includes periodization of training and volume, as well as intensity
and type of training in each training cycle (Table 2). In the general preparation period the
requirements for carbohydrates are higher in the absolute value because of the high training
volume. During this period, athletes may need 6-12 g/kg BW/day. During the specific general
preparation and the competition phases, the intensity of training is high, and because an
important part of the workout is resistance training, the recommended carbohydrate intake is
6-10 g/kg BW/day. This amount is difficult to consume when normal food is eaten because it
is equivalent to 0,5-2 kg of spaghetti, and gastrointestinal intolerance is frequently present
during prolonged and/or intensive training sessions, so that athletes do not fell like eating.
(22). Furthermore, it seems that more than the absolute amount of carbohydrate intake, it is
important to strictly follow the carbohydrate replenishment strategies. For these reasons, it is
frequently recommended for elite athletes to consume concentrated carbohydrate drinks or
supplements. Ensuring strategic carbohydrate availability at critical training points is not
important only for optimal training performance, but is also a key to the strategies for immune
system protection, injury prevention, and as preventive measures against overtraining. It is a
common problem that many strength and power athletes follow a protein centred diet with a
too low daily carbohydrate intake. Protein intake of more than 20% of the daily energy intake
may displace carbohydrate intake and have harmful effect on performance and health. A low
carbohydrate and high protein diet results in metabolic acidosis, which ensues within 24 h and
persists for at least 4 days (18). This appears to be the result of an increase in the circulating
concentrations of strong organic acids, particularly free fatty acids and 3-hydroxybutyrate,
together with an increase in the total plasma protein concentration. It has been proposed that
this acidosis, rather than the decrease in the muscle glycogen content, is responsible for the
reduced exercise capacity during high-intensity exercise.
Another frequent problem is that the nutritional intake in female athletes is considerably lower
than in male athletes and is on the lower limit of the recommended carbohydrate intake. It has
been shown in several studies that female athletes follow a diet with 3-15% of carbohydrates.
Such a low carbohydrate intake does not allow for the optimal replenishment of glycogen
reserves. This results, for example, in a shorter time until exhaustion at a given activity, and it
threatens the health of female athletes.
Carbohydrate intake during exercise
Many power sports have characteristic forms of training to develop the agility and technical
ability of the specific sport. The intake of carbohydrates during this form of exercise does not
only ensure enough substrate for the generation of energy for muscular work, but it also
Copyright © by ESPEN LLL Programme 2015 10
supports the neuromuscular metabolic processes and prevents cognitive exhaustion (41).
However, at high intensity exercise, gastrointestinal tract function is often compromised.
Gastric or intestinal intolerance prevents effective intake of nutrients and fluids. In this case, a
nutritional strategy with carbohydrate mouth washing, without carbohydrate consumption,
could be a potential nutritional strategy for improving performance in a high intensity sport. In
an experiment on multiple 5 seconds cycle sprints with a 6% glucose mouth rinse,
improvement in peak and mean power output in the first of the five sprints was reported. But
in the final (5th) sprint, performance was significantly lowered in the glucose rinse condition
compared to placebo (42). The performance drop was offset by caffeine ingestion. At the
present state of knowledge we cannot give yet the recommendation to follow this strategy.
Carbohydrate intake after exercise
Considering the evidence, and the substantial reliance of power and strength athletes on
carbohydrate metabolism as fuel, maintaining a high intramuscular glycogen content at the
onset of training seems beneficial for the desired resistance training outcomes. The IOC, ISSN,
and ACSM all recommend post-exercise carbohydrate intake in the range of 1.0-1.5 g/kg BW
to increase recovery from the exercise (21-24). The common recommendation is that
carbohydrates should be ingested within 30 minutes after exercise in order to achieve higher
glycogen levels. This timing is important for athletes who have a high training volume, who
exercise with a higher intensity more than once a day, or who perform resistance exercises by
the same muscle group again on the same day. Carbohydrates should be ingested within 30
minutes after exercise and then again every two hours for 4-6 hours. If an athlete rests for 1-2
days between the exercise sessions or events, specific nutrient-timing strategies are not as
important, provided that daily carbohydrate requirements are met according to the level of
activity. However, in case of limited time between exercise sessions, e.g. training more than
once per day or events that comprise multiple-stage races, nutrient timing and recovery are of
critical importance.
The addition of protein intake to the carbohydrate intake close to the time of exercise may
increase muscle protein synthesis, fat-free mass and muscle strength, and may prevent
muscle damage compared to the effects of carbohydrate intake alone (see Section 3.2.2.).
3.2.2. Protein Intake
Daily protein intake
Athletes’ daily needs for protein intake probably depend primarily on the quantity and quality
of training and not so much on the specific sport. Elite athletes, who effectuate a large amount
and intensity of training, generally cover their protein needs with a daily protein intake in the
range of 1.6 -1.7 g/ kg BW/day, which corresponds with the IOC guidelines (200). Judging by
the research performed, a higher protein intake is not sensible, as it does not contribute to
increased protein synthesis or to better recovery after training (43). A protein intake larger
than 1.7 g/kg BW/day increases the catabolism of amino acids without an additional
hypertrophic effect. The superfluous proteins are broken down to lose their nitrogen, but the
carbon may be used for other purposes: glucose formation, fatty acids synthesis or oxidation.
For the metabolic effect, the type of proteins consumed, the time of consumption relative to
the time of training, and the metabolic state prior to training (fasted or fed) are all more
important than the absolute amount of protein intake of a sportsman (42).
There is also evidence that the daily protein requirements of experienced resistance-trained
athletes are reduced because an intensive period of resistance training reduces the protein
Copyright © by ESPEN LLL Programme 2015 11
turnover and improves net protein retention (44). Burd et al. reported that an acute bout of
resistance training in untrained subjects stimulates both mitochondrial and myofibrillar protein
synthesis, whereas in trained subjects, protein synthesis becomes more preferential over the
myofibrillar component (45). This suggests that the more trained power and strength athletes
may be paying closer attention to protein timing and type in order to optimize the rates of
muscular adaptation.
In young subjects, about 20-25 g of proteins maximally stimulates protein synthesis, and there
is evidence that wider distribution of daily protein may lower protein breakdown. Instead of
focusing on total daily protein intake, power and strength athletes should consume 20 g of
protein per meal several times during the day, preferably in close proximity to exercise (46,
47). However, more than 5-6 meals containing protein per day have no further anabolic value
because muscle protein synthesis becomes refractory to persistent aminoacidaemia (48).
Smaller athletes can ingest the recommended daily amount of protein in a normal diet, e.g., 3
-11 servings of chicken or fish contain 75-300 g protein. For larger athletes, as well as for
smaller ones trying to follow the recommendations and consuming proteins immediately after
exercise, the use of protein supplements (mainly powdered forms) provides good options. The
proteins of choice are rapidly digested proteins of high quality (whey proteins, which contain 8-
10 g of essential amino acids per 20 g), which cause the greatest increase in protein synthesis
(49). High quality proteins contain essential branched-chain amino acid leucine, which is
thought to play a central role in mediating mRNA translation for muscle protein synthesis.
Leucine is also a key amino acid for the stimulation of muscle protein synthesis via the cell
TOR system (53, 50-52,53).
Protein intake before and during strength and power training
It seems that there are not enough data available to support general guidelines for protein
intake before and during strength and power training. The ISSN recommends that, depending
on the individual’s exercise duration and fitness level, proteins should be included with
carbohydrates in the pre-event meal before resistance exercises, or when a desired change in
body composition is required (21). This can be achieved by including 0.15-0.25 g/kg BW of
protein with the recommended 1-2 g/kg BW carbohydrates in the pre-event meal 3-4 hours
before training or competition.
The IOC states that although there has been some evidence that supports the intake of protein
before exercise, the follow-up studies have failed to unequivocally support this practice (20,
54-57).
Protein intake after exercise
Regarding acute protein dosage following resistance exercise it seems that 20-25g of proteins
maximally stimulates protein synthesis. This dosage is recommended also by IOC (20, 43, 58).
However, the absolute amount of protein and the precise timing of protein intake are still
difficult to establish. Larger and older athletes probably need more protein, up to 40g (43, 59).
Classical recommendations for protein consumption (at least 25 g) as soon as possible after
resistance training to promote a twofold increase in protein synthesis following the exercise,
which is counterbalanced by the accelerated rate of proteolysis, was discussed in a paper by
Aragon and Schoenfeld (40, 58, 53). They proposed that this recommendation is valid when
training is initiated more than ~3–4 hours after the preceding meal, or minor pre-exercise
nutritional interventions can be undertaken if a significant delay in the post-exercise meal is
anticipated (40). Despite the fact that a clear benefit from consuming the proteins as soon as
Copyright © by ESPEN LLL Programme 2015 12
possible after exercise, as opposed to delaying consumption, has been demonstrated in a
study by Levenhagen et al., good evidence based support for this practice is still lacking
(40,46).
It’s not entirely clear that the combined ingestion of carbohydrate and protein further
stimulate muscle protein synthesis (60, 61). However, with the co-ingestion of carbohydrates
and proteins the athlete can maximize training adaptation and restore muscle glycogen.
Relative to body mass, the recommended amount of protein is 0.4 g/kg combined with a 0,8
g/kg carbohydrates (62).
Protein intake in ageing athletes
Ageing muscle responds less well after the intake of amino acids. This phenomenon has been
named “anabolic resistance.” In elderly people, more protein is required to reach maximal
rates of muscle protein synthesis, compared to young individuals. This means that the muscles
of ageing athletes appear to be resistant to normal anabolic stimulation with amino acids and
resistance exercise (63, 64). There is evidence that this may is associated with decreased
intramuscular expression and/or activation (phosphorylation) of amino acid sensing/signalling
proteins, induced by low grade inflammation present in most elderly people due to comorbidity
or the aging process itself (65). Low grade inflammation activates immune responses and the
synthesis of acute phase proteins taking place predominantly in the splanchnic region (liver,
spleen, immune cells in the intestinal tract etc). This causes a greater uptake and utilization of
the protein ingested in the splanchnic region than in a younger healthier age group and
diminishes the availibility of amino acids for peripheral organs (muscle, skin, bone etc). This
may explain the lower fractional synthesis rate (FSR) of muscle protein after protein ingestion,
and therefore also questions the validity of the term “anabolic resistance” to dietary protein in
the elderly (66, 67, 68).
These findings explain why older subjects require higher quantities of protein (up to 40 g after
resistance exercise) to acutely stimulate equivalent muscle protein synthesis above rest and
optimize the training adaptation (63, 68). Yang et al. found that elderly subjects displayed
greater increases in muscle protein synthesis when consuming a post exercise dose of 40 g
whey protein compared to 20 g (69). After the resistance exercise a light meal of 20-40 g of
proteins should be consumed, containing at least 2-2,5g of leucine.
Timing the protein intake around resistance exercise may be beneficial for stimulation of
muscle protein synthesis in elderly athletes. So, a meal with 20-25g of high quality proteins
should be eaten 3-4 hours before exercise, and a light meal of 20 -40 g of proteins, containing
2 -2.5 g of leucine, should be consumed afterwards;
Thus, when considering protein feeding strategies that will acutely increase muscle protein
synthesis in the elderly, a protein source with high leucine content and rapid digestion kinetics
(e.g. a high-leucine sources such as dairy proteins) in order to promote a transient leucinemia
‘spike’, would be an effective option.
However, reservations should be made regarding the significance of FSR’s measured shortly
after exercise and after ingesting a protein/ amino acid bolus (69). Only synthesis is measured
after a few hours and it is uncertain what happens simultaneously with protein degradation
and what happens in the long term. It may for instance be possible that a protein/amino acid
bolus increases peak muscle FSR shortly after exercise, but that a protein/carbohydrate meal
will lead to a more tapered release of amino acids to the circulation, diminish gluconeogenesis
and exert a superior net anabolic response than a single protein bolus.
Copyright © by ESPEN LLL Programme 2015 13
Protein intake and caloric deficit
According to Phillips and van Loon, strength and power athletes who, for any reason
(aesthetic, competition in weight categories, and optimal competitive body composition with
low body mass in running and similar), attempt to reduce the body fat or make weight with
caloric restrictions for should increase their protein intake in hypocaloric condition to 1,8 – 2,7
1,8 – 2,7 g/ kg BW/day (71). The IOC recommendation for optimizing body composition in
favour of losing fat and gaining muscle mass is by decreasing daily carbohydrate intake (3-4
g/kg BW/day) and increasing daily protein intake to the same level as was suggested by
Phillips and Van Loon (1.8-2.7 g/ g/kg BW/day) (20).
On theoretical grounds increasing protein intake and diminishing carbohydrate intake is
promoting gluconeogenesis and ureagenesis from amino acids. This slightly increases total
energy expenditure. Alternative approach would be to have normal intake of protein
(recommended for sportsmen not wanting to lose fat mass), add normal amounts of
carbohydrates but to diminish fat intake.
In a recent metaanalysis, it has been proposed that the protein needs for energy-restricted
resistance-trained athletes are about 2.3-3.1 g/kg of fat free mass (72). In case of a more
severe energy deficit or a higher level of leanness, protein intake should be upgraded. Finally,
in an evidence-based recommendation for natural body building contest preparation from
2014, the authors recommended the same regime of protein intake: 2.3-3.1 g/kg of fat free
mass per day in three to six meals per day, with a meal containing 0,4-0,5 g of protein prior to
and after to resistance training (25).
3.2.3. Fat Intake
A modest nutritional intake of fats is necessary throughout all training phases because it
ensures the absorption of fat-soluble vitamins, substrates for the synthesis of hormones, and
the maintenance of integrity of cellular membranes and myelin neural sheaths.
Fat in the form of intramuscular triglycerides is a good source of energy during exertion for
longer training sessions with moderate intensity of up to 85% VO2. For power sports athletes,
this form of training is an important part of the general preparation phase, and in this case
endogenous fat is an important source of fuel. For >2 hours endurance training, the quantity
of fats that should satisfy the needs for replacement of depleted reserves of intramuscular
triglycerides is estimated at 2 g/kg BW/day (73).
Therefore the nutritional recommendation for fat intake during this phase of training is 1, 5–2
g/kg BW/day (19). A higher fat intake may compromise muscle glycogen recovery and tissue
repair because of a lower daily carbohydrate and/or protein intake. This can be a practical
issue for strength and power athletes as the reported fat intake in this group of athletes is
generally higher than that recommended for healthy nutrition (8). Fat intake is often derived
from sources which are rich in saturated fats. This is probably connected with the emphasis on
animal foods as a good protein source. This nutritional practice can also partly explain the
lower dietary intake of carbohydrates. It is probable that the iso-energetic replacement of fat
with carbohydrate would have a favourable effect on performance and long term health.
On the other hand, athletes who are gaining weight frequently cut fat sources from their diet.
The IOC recommendation is that athletes should not follow a diet with less than 15-20% of
total energy derived from fats (20).
Copyright © by ESPEN LLL Programme 2015 14
3.2.4. Water
The dehydration effect in strength and power sports is not well documented. Experimental data
show that that ability to perform resistance exercise and total peak cycling power are reduced
with dehydration by about 3% of body mass (74,75). Kraft with co-workers studied the
influence of dehydration on muscular strength and endurance, and on single and repeated
anaerobic sprint bouts. They concluded that the critical level of water deficit affecting
anaerobic performance (approximately 3-4%, depending on the mode of exercise) is larger
than the deficit impairing endurance performance (approximately 2%) (76). From a
performance and health point of view, as with all athletes, strength and power athletes are
advised to begin the resistance and sprint training sessions in a well hydrated state, and then
drink sufficiently to limit body mass loss to 2-3%.
3.3. Summary of Nutritional Strategies to Optimize Recovery
In Table 3, nutritional strategies to optimize recovery in different training situations are
summarized (19). The total intake of energy and nutrients is important, but it is probably even
more important that the intake of metabolic energetic and nutritional substrates is adjusted to
the individual’s needs, depending on the amount of training. Thus, an elite sportsman must
have the support of an appropriately adjusted nutritional strategy, which assures:
the recovery of muscular energy reserves, primarily in the form of glycogen, and with
endurance training, in the form of intramuscular triglycerides;
protein intake for optimal protein synthesis;
sufficient intake of fluids for rehydration.
Currently we know that carbohydrates and proteins should be ingested in close temporal
proximity to the exercise bout in order to support recovery and the anabolic response to
training.
Copyright © by ESPEN LLL Programme 2015 15
Table 3
Recommendations for recovery nutrition in different training situations (adapted
from 19).
Long aerobic/ endurance training
Intensive short
duration or
prolonged
resistance training
Technical
drills/short
duration
resistance
training
Situations of short
recovery (<4h)
Exercise
characteristics
Primary
metabolism
Prolonged aerobic
exercise (>1h)
Oxidative
metabolism
(fat,CHO)
High intensity
exercise (20-40min)
Non-oxidative
glycolytic (CHO)
Low volume of
explosive
movements
Glycolytic and
phosphagen
(PCr+CHO)
Multiple races or
training sessions on
the same day
Training
objective
Enhance oxidative enzymes, fat metabolism, endurance Energy replacement (fat, CHO)
Enhance: glycolytic enzymes, buffering capacity, lactate tolerance, muscle power Energy replacement (CHO)
Submaximal and maximal muscular strength, technique and economy development Energy needs are low
Specific to training and racing demands Some energy replacement (CHO)
Specific
recovery needs
Carbohydrate
intake of primary
importance for
glycogen re-
synthesisProtein
for muscle
recovery and re-
modelling
Carbohydrate intake
of primary
importance for
glycogen re-synthesis
Protein for muscle
recovery and re-
modelling
Lower
carbohydrate
needs (some
glycogen re-
synthesis)
Protein for muscle
recovery and re-
modelling
Carbohydrate intake
of primary
importance for
glycogen re-
synthesis
Focus on foods that
are GI tolerable for
subsequent exercise
(minimize Fat, PRO
intake)
Macronutrients
recommendati
ons (within 2
hours)
(g/kg BW)
CHO* 1.2-1.5
PRO** 0.3
fat 0.2- 0,3
CHO 1.2-1,5
PRO 0.3
fat minimal
requirements
CHO 0.5-1,0
PRO 0.3
fat minimal
requirements
CHO 1.2-1.5
PRO minimal
requirements
fat minimal
requirements
* CHO, carbohydrate
**PRO, protein
3.4. Summary
In this section basic considerations about nutritional support in power and strength sports are
discussed, with emphasis on energy and protein intake. Nutritional strategies should be
periodized and personalized according to training needs and individual characteristics. An
overview of recovery strategies is presented. Consensus documents and papers in References
are recommended for further reading.
4. Ergogenic Supplements for Power Sports
The use of performance enhancing substances in strength and power sports is widespread and
has a long history. These substances are often used indiscriminately and can have negative
health consequences. Such indiscriminate use is promoted by the industry, and the majority of
products on the market fail to reach expected goals (77). Competitive sportsmen also face a
Copyright © by ESPEN LLL Programme 2015 16
high risk of positive doping substance tests since nutritional supplements may be
contaminated with these substances.
A fundamental task of sports nutrition consultants is therefore to construct solid nutritional
support for an optimally effective training plan and for a successful competitive strategy. Such
a nutritional plan should include nutritional supplements on the basis of scientifically proven
benefit in the specific situation of the individual sportsman. As with basic nutritional support,
the use of nutritional supplements requires a personalized approach.
In an ISSN recommendation (2010) regarding the use of dietary supplements based on the
basis of available scientific literature, the following substances are recognized as “apparently
effective and generally safe” in strength and power sports: caffeine, creatine monohydrate, β-
alanine and sodium bicarbonate (22).
Other supplements in this class are water and energy supplements in the form of carbohydrate
drinks and snacks. For performance effects of proper carbohydrate supplementation and
hydration see Sections 3.2.1 and 3.2.4.
4.1. Caffeine
Caffeine ingestion may improve strength, power and resistance exercise performance (78, 79).
The optimal effective dosage is not clear, an ergogenic effect was reported with buccal
administration of only 100mg caffeine (chewing gum) (80). This represents a very low dose of
caffeine, equivalent to the dose in an average cup of coffee. The ergogenic effect of lower
caffeine doses, up to 3mg/kg BW, is probably connected with stimulation of the central
nervous system. This effect is more pronounced in well trained athletes who are not regular
caffeine consumers. Moderate to high caffeine doses (5g/kg BW and up) may increase the
intestinal absorption of carbohydrates during exercise and may stimulate the resynthesis of
muscle glycogen. This has the potential to speed up the recovery process in elite athletes (79).
A dosage of up to 10mg/kg BM is unlikely to increase performance benefits because of the side
effects, such as headaches, tremor, tachycardia, anxiety, nervousness, insomnia, increased
urination, and gastrointestinal discomfort.
4.2. Creatine Monohydrate
Creatine monohydrate is probably the most effective nutritional supplement for strength and
power sport athletes (14, 22). Data from numerous studies have indicated that the use of
creatine increases the high intensity exercise capacity, particularly when there are repeated
bouts of intensive exercise. Ingestion of creatine supports an increase in muscle mass, which
may result from an improved ability to perform high intensity exercise and thus train harder. A
more intensive workout can promote a greater training adaptation and muscle hypertrophy
(14, 81, 82).
Creatine monohydrate appears to be the most useful form of creatine supplementation and the
addition of carbohydrates and proteins to the creatine supplement can increase muscle
retention of creatine (22).
Different protocols for creatine ingestion/loading are recommended. Already in 1986, Hultman
and coworkers showed that the ingestion of creatine monohydrate for 6 days increases skeletal
muscle creatine content by about 20% (83). According to the current guidelines, the fastest
method to increase muscle creatinine appears to be to consume 0,3 g/kg BM/day of creatine
monohydrate for at least 3 days (usually 20 g for 5 days), followed by 3-5 g thereafter to
maintain elevated stores (22). Ingesting a smaller amount of creatine, 2-3 g/day, will increase
Copyright © by ESPEN LLL Programme 2015 17
the muscular creatine concentration in 3-4 weeks. The performance effect of this method is not
well supported by scientific data.
4.3. β-alanine
β-alanine is a non-essential amino acid.In a dipeptide form with histidine it forms carnosine.
Carnosine is a potent intramuscular buffer, found at high concentrations in the cytoplasm of
skeletal muscles, particularly in type 2 fibres (15). Its nitrogen containing imidazole ring can
buffer H+ ions with a pKa of 6.83 and it slows the decline in pH during intensive exercise.
Carnosine buffering represents about 7% of intracellular buffering capacity. Supplementation
with β-alanine in doses of 3-6 g for about 4-8 weeks can increase the amount of muscle
carnosine by up to 40-50% of its normal level (84). This may double the carnosine buffering
capacity in the muscle cell and is the basis for positive anaerobic performance during intense
exercise lasting 1-6 min (high intensity track and field, swimming, rowing, etc.).
4.4. Sodium Bicarbonate
Ingestion of sodium bicarbonate can increase plasma bicarbonate and may slow the
development of acidosis related to fatigue during high intensity exercise (6). Bicarbonate
loading (e.g., 0,3 g/kg BW, or 20 g taken 1-3 h prior to exercise, or 5 g take twice per day for
5 days) can be an effective way to augment the blood buffering capacity in events lasting 1-6
minutes or repeated sprints (85). Supplementation with sodium bicarbonate is not suitable for
everybody as experience shows that about 50% of athletes develop gastrointestinal
discomfort, which has a negative influence on performance.
Given many inconsistencies in the literature regarding the effect of sodium bicarbonate on
performance and the dosing regimen, as well as the high incidence (50%) of gastrointestinal
upset, the athlete should experiment during training or in low key competition to find the
optimal ergogenic response for the individual athlete.
4.5. β-hydroxy-β-methylbutyrate
According to the ISSN exercise & sport nutritional recommendations from 2010, β-hydroxy-β-
methylbutyrate (HMB), a derivate of leucine, may be another potentially effective metabolic
substrate coming from proteins for muscle building (22). Supplementing the diet with 1.5 to 3
g/day of HMB during resistance training has been reported to increase muscle mass and
strength among previously untrained subjects (86-90).
In the elderly people, a similar muscle anabolic response to dietary HMB ingestion was
reported as in young adults (91).
4.6. Summary
The use of performance enhancing substances in strength and power sports must be effected
via sensible supplementation, and the oversight of a proper nutritional support in a specific
training or competitive situation. It should be limited to the approved substances and
individually adjusted.
Copyright © by ESPEN LLL Programme 2015 18
5. References
1. Hargreaves M. Exercise physiology and metabolism. In: Burke L, Deakin L. Clinical
sports nutrition, eds. 3rd ed. Sydney: McGraw-Hill; 2006, p 1-17.
2. Units of Measurement and Terminology. In: Komi PV, eds. Strength and power in
sport. 2nd ed. Oxford: Blackwell Scientific Publications; 2003, p. xiii.
3. Knuttgen HG, Komi PV. Basic consideration for exercise. In: Komi PV, eds. Strength
and power in sport. 2nd ed. Oxford: Blackwell Scientific Publications; 2003, p. 3-7.
4. Jandačka D, Vaverka F. A regression model to determine load for maximal power
output, Sports Biomechanics 2008;7:361-371.
5. Wakeling JM, Blake OM, Chan HK. Muscle coordination is a key to the power output
and mechanical efficiency of limb movements. J Exp Biol 2010;213,487-92.
6. Stellingwerff T, Maughan RJ, Burke LM. Nutrition for power sports: middle-distance
running, track cycling, rowing, canoeing/kayaking, and swimming. J Sports Sci 2011;
29 (S1):S79-S89.
7. Knuttgen HG, Kraemer WJ. Terminology and measurement in exercise performance. J
Appl Sports Sci Res 1987:1:1-10.
8. Slater G, Phillips SM. Nutrition guidelines for strength sports: sprinting, weightlifting,
throwing events, and bodybuilding. J Sports Sci 2011;29(S1):S67-S77.
9. Rønnestad BR, Mujika I. Optimizing strength training for running and cycling
endurance Scand J Med Sci Sports 2014;24:603-612.
10. Hoffman JR, Cooper J, Wendell M, Kang J. Comparison of Olympic vs. traditional
power lifting training programs in football players J Strength Cond Res 2004;18:
129-35.
11. Folland JP, Williams AG. The adaptations to strength training: morphological and
neurological contributions to increased strength. Sports Med 2007;37:145-68.
12. Maughan RJ, Gleeson M. Energy for muscle contraction. In: Maughan RJ, Gleeson M.
The Biochemical Basis of Sports Performance 2nd ed. Oxford: University press; 2010,
p.59-62.
13. Billeter R, Hoppeler H. Muscular basis of strength. In: Komi PV (eds), 2nd ed.
Strength and power in sport. Oxford: Blackwell Scientific Publications; 2003, p. 50-
72.
14. Volek JS, Rawson ES. Scientific basis and practical aspects of creatine
supplementation for athletes. Nutrition 2004;20:609–14.
15. Artioli GG, Gualano B, Smith A, Stout J, Lancha AH Jr. Role of beta-alanine
supplementation on muscle carnosine and exercise performance. Med Sci Sports
Exerc 2010;42:1162-73.
16. Cochran AJ, Percival ME, Tricarico S, Little JP, Cermak N, Gillen JB, et al. Intermittent
and continuous high-intensity exercise training induce similar acute but different
chronic muscle adaptations. Exp Physiol 2014;99:782-91.
17. Schiaffino S. Fibre types in skeletal muscle: a personal account. Acta Physiol 2010;
199:451–63.
18. Maughan RJ, Greenhaff PL, Leiper JB, Ball D, Lambert CP, Gleeson M. Diet
composition and the performance of high-intensity exercise. J Sports Sci 1997;15:
265-75.
19. Stellingwerff , Boit MK, Res PT. Nutritional strategies to optimize training and racing
in middle-distance athletes. J Sports Sci 2007;25 (S1):S17-28.
20. International Olympic Committee (IOC) consensus statement on sports nutrition
2010. J Sports Sci 2011;29(SI):S3-S4.
Copyright © by ESPEN LLL Programme 2015 19
21. Kerksick C, Harvey T, Stout J, et al. International Society of Sports Nutrition position
stand: nutrient timing. Int J Soc Sports Nutr 2008;5:17 [homepage on the Internet].
Available from: http://www.jissn.com/content/pdf/1550-2783-5-17.pdf
22. Kreider RB, Wilborn Cd, Taylor L, et al. ISSN exercise and sport nutrition review:
research and recommendations. Int J Soc Sports Nutr 2010;7:7.
Available from: http://www.biomedcentral.com/content/pdf/1550-2783-7-7.pdf
23. Manore MM, Barr SI, ButterfieldGA. Position of the American Dietetic Association,
Dietitians of Canada, and the American College of Sports Medicine: Nutrition and
athletic performance. J Am Diet Assoc 2000;100:1543-56.
24. Rodriquez NR, DiMarco NM, Langley S. Position of the American Dietetic Association,
Dietitians of Canada, and the American College of Sports Medicine: Nutrition and
athletic performance. J Am Diet Assoc. 2009;109:509-527.
Available from: http://journals.lww.com/acsm-msse/Fulltext/2009/03000/a.
25. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural
bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports
Nutr 2014:12;11-20.
26. Spencer MR, Gastin PB. Energy system contribution during 200- to 1500-m running in
highly trained athletes. Med Sci Sports Exerc 2001;33:157-62.
27. Tesch PA, Colliander EB, Kaiser P. Muscle metabolism during intensive, heavy-
resistance exercise. Eur J Appl Physiol O 1986;55;4:362-6.
28. MacDougall JD, Ray S, Sale DG, McCartney N, Lee P, Garner S: Muscle substrate
utilization and lactate production. Can J Appl Physiol 1999;24209–15.
29. Häkkinen K. Neuromuscular dysfunction is additional important factor of fatigue. Int J
Sports Med 1993;14:53-9.
30. Rowbottom D J. Periodization of Training. In: Garrett WE, Kirkendall DT. Periodization
of Training. Philadelphia: Lippincott Williams & Wilkins; 2000. p. 499.
31. Krüger A. Periodization or Peaking at the right time. In: Track Technique 54; 1973.
pp.1720-4.
32. Burke LM, Hawley JA, Wong SH, et al. Carbohydrates for training and competition. J
Sports Sci 2011;29(S1):S17-S27.
33. Loucks AB, Kiens B, Wright HH. Energy availability in athletes. J Sports Sci 2011;29
(S1):S7-S15.
34. Heymsfield SB, Chirachariyavej T, Rhyu IJ, Roongpisuthipong C, Heo M, Pietrobelli A.
Differences between brain mass and body weight scaling to height: potential
mechanism of reduced mass-specific resting energy expenditure of taller adults. J
Appl Physiol (1985) 2009;106:40-8.
35. Burke LM, Cox GR, Culmmings NK, Desbrow B. Guidelines for daily carbohydrate
intake: do athletes achieve them? Sports Med 2001;31:267-99.
36. Cheetham ME, Boobis LH, Brooks S, Williams C.Human muscle metabolism during
sprint running. J Appl Physiol (1985). 1986;61:54-60.
37. Blomstrand E, Saltin B, Blomstrand E, Saltin B: Effect of muscle glycogen on glucose,
lactate and amino acid metabolism during exercise and recovery in human subjects. J
Physiol 1999;514:293–302.
38. Lemon PW, Mullin JP: Effect of initial muscle glycogen levels on protein catabolism
during exercise. J Appl Physiol 1980;48:624–9.
39. Maughan RJ, Poole DC. The effects of a glycogen-loading regimen on the capacity to
perform anaerobic exercise. Eur J Appl Physiol Occup Physiol 1981;46:211-9.
40. Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a postexercise anabolic
window?. J Int Soc Sports Nutr 2013;10:5.
Copyright © by ESPEN LLL Programme 2015 20
41. Currell K, Conway S, Jeukendrup AE Carbohydrate ingestion improves performance of
a new reliable test of soccer performance. Int J Sport Nutr Exerc Metab 2009;19:34-
46.
42. Beaven CM, Maulder P, Pooley A, Kilduff L, Cook C. Effects of caffeine and
carbohydrate mouth rinses on repeated sprint performance. Appl Physiol Nutr Metab
2013;38:633–637.
43. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, et al. Ingested
protein dose response of muscle and albumin protein synthesis after resistance
exercise in young men. Am J Clin Nutr 2009;89:161–8.
44. Hartman JW, Moore DR, Phillips SM. Resistance training reduces whole-body protein
turnover and improves net protein retention in untrained young males. Appl Physiol
Nutr Metab 2006;31:557-64.
45. Burd NA, Tang JE, Moore DR, Phillips SM: Exercise training and protein metabolism:
influences of contraction, protein intake, and sex-based differences. J Appl Physiol
2009;106:1692–701.
46. Arnal MA, Mosoni L, Boirie Y, Houlier ML, Morin L, Verdier E, et al. Protein feeding
pattern does not affect protein retention in young women. J Nutr 2000;130:1700-4.
47. Moore DR, Tang JE, Burd NA, Rerecich T, Tarnopolsky MA, Phillips SM. Differential
stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at
rest and after resistance exercise. J Physiol 2009 15;587:897-904.
48. Bohé J, Low JF, Wolfe RR, Rennie MJ. Latency and duration of stimulation of human
muscle protein synthesis during continuous infusion of amino acids. J Physiol 2001;
532:575–9.
49. Tang JE, Phillips SM.Maximizing muscle protein anabolism: the role of protein quality.
Curr Opin Clin Nutr Metab Care 2009;12:66-71.
50. Smith K, Barua JM,Watt PW, Scrimgeour CM, RennieMJ. Flooding withL-[1–
13C]leucine stimulates human muscle protein incorporation of continuously infused L-
[1–13C]valine. Am J Physiol. 1992;262:E372–6.
51. Smith K, Reynolds N, Downie S, Patel A, Rennie MJ. Effects of flooding amino acids on
incorporation of labeled amino acids into human muscle protein. Am J Physiol 1998;
275:E73–8.
52. Volpi E, Kobayashi H, Sheffield-Moore M, Mittendorfer B, Wolfe RR. Essential amino
acids are primarily responsible for the amino acid stimulation of muscle protein
anabolism in healthy elderly adults. Am J Clin Nutr 2003;78:250–8.
53. Phillips SM: The science of muscle hypertrophy: making dietary protein count. Proc
Nutr Soc 2011;70:100–3.
54. Tipton KD, Rasmussen BB, Miller SL, et al. Timing of amino acid-carbohydrate
ingestion alters alters anabolic response of muscle to resistance exercise. Am J
Physiol Endocrinol Metab 2001;281:E197-E206.
55. Fujita S, Dreyer HC, Drummond MJ, et al. Essential amino acid and carbohydrate
ingestion before resistance exercise does not enhance postexercise muscle protein
synthesis 2009;106:1730-9.
56. Tipton KD, Elliot TA, Cree MG, et al. Stimulation of net muscle protein synthesis by
whey protein ingestion before and after exercise. Am J Physiol Endocrinol Metab
2007; 292:E71-E76.
57. Potgieter S. Sport nutrition: A review of the latest guidelines for exercise and sport
nutrition from the American College of Sport Nutrition, the International Olympic
Committee and the International Society for Sports Nutrition. S Afr J Clin Nutr 2013;
26:6-16.
Copyright © by ESPEN LLL Programme 2015 21
58. Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum
adaptation. J Sports Sci 2011;29:S29-38.
59. Breen L, Phillips SM: Interactions between exercise and nutrition to prevent muscle
waste during aging. Br J Clin Pharmacol 2012;75:708-15.
60. Loon LJC. Is There a Need for Protein Ingestion During Exercise? Sports Med 2014;
44 (S1):S105–S111.
61. Deutz NEP, Ten Have GAM, Soeters PB, Maughan PJ. Increased intestinal amino-acid
retention from the addition of carbohydrates to a meal. Clinical Nutrition
1995;14:354-64.
62. Rawson ES, Brightbill CE, Stec MJ. Strenght and power events. In: Maughan R, eds.
Sports Nutrition. Willey Blackwell; 2014,p. 551-60.
63. Breen L, Phillips SM: Interactions between exercise and nutrition to prevent muscle
waste during aging. Br J Clin Pharmacol 2013;75:708-15.
64. Bauer J, Biolo G, Cederholm T, Cesari M, Cruz-Jentoft AJ, Morley JE, et al. Evidence-
based recommendations for optimal dietary protein intake in older people: a position
paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013; 14: 542-59.
65. Cuthbertson D, Smith K, Babraj J, et al. Anabolic signaling deficits underlie amino
acid resistance of wasting, aging muscle. FASEB J 2005; 19: 422-4.
66. Boirie Y, Gachon P, Beaufrere B. Splanchnic and whole-body leucine kinetics in young
and elderly men. Am J Clin Nutr 1997;65:489-95.
67. Volpi E, Mittendorfer B, Wolf SE, Wolfe RR. Oral amino acids stimulate muscle protein
anabolism in the elderly despite higher first-pass splanchnic extraction. Am J Physiol
1999;277:E513-20.
68. Paddon-Jones D, Rasmussen BB: Dietary protein recommendations and the
prevention of sarcopenia. Curr Opin Clin Nutr Metab Care 2009;12:86-90.
69. Moore DR, Soeters PB. Biological value of protein. In: The Importance of Nutrition as
an Integrated Part of Disease Management. Nestle Nutr Inst Workshop Ser. 2015 (in
press).
70. Yang Y, Breen L, Burd NA, Hector AJ, Churchward-Venne TA, Josse AR, et al.
Resistance exercise enhances myofibrillar protein synthesis with graded intakes of
whey protein in older men. Br J Nutr 2012;108:1780–8.
71. Phillips SM, Van Loon LJC. Dietary protein for athletes: from requirements to
optimum adaptation. J Sport Sci;29 (S1):S29-S38.
72. Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein
during caloric restriction in resistance trained lean athletes: a case for higher intakes.
Int J Sport Nutr Exerc Metab 2014;24:127-38.
73. Decombaz J. Nutrition and recovery of muscle energy stores after exercise.
Sportmedizin und Sporttraumatologie 2003;51:31-38.
74. Kraft JA, Green JM, Bishop PA, Richardson MT, Neggers YH, Leeper JD.Impact of
dehydration on a full body resistance exercise protocol. Eur J Appl Physiol 2010;109
:259-67.
75. Jones LC, Cleary MA, Lopez RM, Zuri RE, Lopez R. Active dehydration impairs upper
and lower body anaerobic muscular power. J Strength Cond Res 2008;22:455-63.
76. Kraft JA, Green JM, Bishop PA, Richardson MT, Neggers YH, Leeper JD.The influence
of hydration on anaerobic performance: a review. Res Q Exerc Sport 2012;83:282-
92.
77. Maughan RJ, Greenhaff PL, Hespel P. Dietary supplements for athletes: emerging
trends and recurring themes. J Sports Sci 2011;29(S1):S57-S66.
78. Duncan MJ, Oxford SW. The effect of caffeine ingestion on mood state and bench
press performance to failure. J Strength Cond Res 2011;25:178-85.
Copyright © by ESPEN LLL Programme 2015 22
79. Spriet LL. Caffeine and Exercise Performance. In: Maughan R, eds. Sports Nutrition.
Willey Blackwell; 2014, p. 551-60.
80. Bellar D, Judge LW. Use of caffeine chewing gum as an ergogenic aid. Strength Cond
J 2013;33:66-68.
81. Volek JS, Duncan ND, Mazzetti SA, Putukian M, Gomez AL, Staron RS, et al.
Performance and muscle fibre adaptations to 12 weeks of creatine supplementation
and heavy resistance training. Med Sci Sports Exerc 1999;31:1147–1156.
82. Willoughby DS, Rosene J. Effects of oral creatine and resistance training on myosin
heavy chain expression. Med Sci Sports Exerc 2001;33:1674-81.
83. Hultman E, Söderlund K, Timmons JA, Cederblad G, Greenhaff PL. Muscle creatine
loading in men. J Appl Physiol (1985) 1996;81(1):232-7.
84. Harris RC, Stellingwerff T. Effect of β-alanine supplementation on high-intensity
exercise performance. Nestle Nutr Inst Workshop Ser 2013;76:61-71.
85. McNaughton LR, Siegler J, Midgley A. Ergogenic effects of sodium bicarbonate. Curr
Sports Med Rep 2008;7:230-6.
86. Levenhagen DK, Gresham JD, Carlson MG, Maron DJ, Borel MJ, Flakoll PJ.
Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and
protein homeostasis. Am J Physiol Endocrinol Metab 2001; 280:E982–93.
87. Gustavo D Pimentel, José C Rosa, Fábio S Lira, Nelo E Zanchi, Eduardo R Ropelle, Lila
M Oyama et al. β-Hydroxy-β-methylbutyrate (HMβ) supplementation stimulates
skeletal muscle hypertrophy in rats via the mTOR pathway. Nutr Metab 2011;8:11.
88. Wilson GJ, Wilson JM, Manninen AH: Effects of beta-hydroxy-methylbutyrate (HMB)
on exercise performance and body composition across varying levels of age, sex, and
training experience: A review. Nutr Metab 2008,5:1.
89. Nissen SL, Abumrad NN. Nutritional role of the leucine metabolite β-hydroxy-β-
methylbutyrate (HMB) J Nutr Biochem 1997;8:300–11.
90. Nair KS: Leucine as a regulator of whole body and skeletal muscle protein metabolism
in humans. Am J Physiol 1992;263: E928-34.
91. Vukovich MD, Stubbs NB, Bohlken RM: Body composition in 70-year-old adults
responds to dietary beta-hydroxy-beta-methylbutyrate similarly to that of young
adults. J Nutr 2001;131:2049-52.