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Exercise and functional foods
Wataru Aoi12*, Yuji Naito3 and Toshikazu Yoshikawa23
•
*Corresponding author: Wataru Aoi [email protected]
Author Affiliations
1Research
Center for Sports Medicine, Doshisha University, Kyoto 602-8580, Japan
2Department
of Inflammation and Immunology, Graduate School of Medical Science, Kyoto
Prefectural University of Medicine, Kyoto 602-8566, Japan
3Department
of Medical Proteomics, Graduate School of Medical Science, Kyoto Prefectural
University of Medicine, Kyoto 602-8566, Japan
For all author emails, please log on.
Nutrition Journal 2006, 5:15 doi:10.1186/1475-2891-5-15
The electronic version of this article is the complete one and can be found online
at:http://www.nutritionj.com/content/5/1/15
Received:
31 March 2005
Accepted:
5 June 2006
Published:
5 June 2006
© 2006 Aoi et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution
License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Abstract
Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance,
conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements
containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting
fields to provide a boost to the recommended daily allowance. In addition, several natural food
components have been found to show physiological effects, and some of them are considered to be
useful for promoting exercise performance or for prevention of injury. However, these foods should
only be used when there is clear scientific evidence and with understanding of the physiological
changes caused by exercise. This article describes various "functional foods" that have been reported
to be effective for improving exercise performance or health promotion, along with the relevant
physiological changes that occur during exercise.
Introduction
Appropriate nutrition is essential for the proper performance of exercise. In particular, correct nutrition
is critically important for improvement of athletic performance, conditioning, recovery from fatigue after
exercise, and avoidance of injury. Although athletes need to eat a well-balanced basic diet, there are
several nutritional factors that are difficult to obtain at a sufficient level from a normal diet since
athletes require more nutrients than the recommended daily allowances. Thus, nutritional
supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in
various sporting fields, partly because these supplements are easily taken before, during, and/or after
exercise. Several natural food components have also been shown to exert physiological effects, and
some of them are considered to be useful (when ingested at high doses or continuously) for improving
athletic performance or for avoiding the disturbance of homeostasis by strenuous exercise. Recently,
food components with physiological actions have been called "functional foods" and the effects of
such foods have been scientifically investigated. This article introduces some functional foods,
including basic nutrients, which have been demonstrated to have a beneficial influence on the
physiological changes that occur during exercise.
Replenishment of Water
Water is the main constituent of the human body, and it plays an essential role in circulatory function,
chemical reactions involved in energy metabolism, elimination of waste products, and maintenance of
the body temperature and plasma volume. When the body temperature rises due to the intense
exercise or a high ambient temperature, sweating occurs in order to radiate heat [1-3], leading to the
loss of a large amount of water and electrolytes such as sodium. This loss of body fluid impairs
thermoregulation and circulatory system, leading to a decline of athletic performance [4,5]. Therefore,
to maintain homeostasis and athletic performance, replenishment of water and electrolytes is
essential before and during or after exercise. Generally, it is believed to be useful to drink isotonic
fluid that contains electrolytes such sodium, potassium, and chloride at concentrations close to those
in body fluids. It has also been suggested that intake of hypotonic fluid may exert a similar or more
rapid effect on replenishment of body water [6,7] because it is rapidly absorbed from the small
intestine along an electrochemical gradient. Also, the sodium concentration (and the osmolality) of
sweat is lower than that of extracellular fluid, so the loss of water with sweating is much greater than
the loss of electrolytes, leading to an increase in the plasma osmotic pressure. On the other hand,
replenishment of water alone is unlikely to maintain homeostasis of body fluid in prolonged exercise
that produces high sweat rates. Taking in only water in prolonged exercise leads to hyponatremia and
a decrease in the osmotic pressure of body fluids and inhibit the release of antidiuretic hormone
resulting in that water intake is suppressed and the urine output is increased (spontaneous
dehydration) [8]. Latzka et al. [9] suggested that during prolonged exercise lasting longer than 90
minutes, fluid drink containing electrolytes and carbohydrate, not water alone, should be considered
to provide to sustain carbohydrate oxidation and endurance performance. Furthermore, several
studies have suggested that glycerol loading has been advocated as one of methods which prevent
high temperature and dehydration in exercise [10,11]. Oral administration of 1.0–1.2 g/kg B.W.
glycerol with water temporarily results in an increase of 300–700 ml body fluid [10,11] and improves
endurance performance compared with placebo [12-14]. Glycerol acts as an osmolyte in body fluid,
which would lead to an elevation of plasma osmolality [10]. Consequently, water reabsorption in the
kidney is increased and urine excretion is decreased, which is considered as one of mechanisms of
the effect.
Improvement of Endurance
Energy consumed during exercise is mainly supplied by carbohydrates and lipids, so it is important for
improvement of endurance to regulate the metabolism of these two substrates. During endurance
exercise, glycogen (an energy substrate for muscle contraction) is gradually depleted, making it
difficult to continue exercising. An effective way to improve endurance is to increase the glycogen
stores in skeletal muscle and the liver before the commencement of exercise. When tissue glycogen
stores are depleted, glycogen synthetase activity is transiently increased, leading to an increase of
glycogen storage by conversion from carbohydrates [15,16]. For instance, it has been reported that
glycogen stores can be increased by eating a low-carbohydrate diet for 3 days from 6 days prior to
competition, followed by a high-carbohydrate diet for the next 3 days, resulting in the storage of 1.5
times more glycogen than normal [17]. If citrate, which inhibits glycolysis, is taken concurrently with a
high-carbohydrate diet, glycogen stores will be further increased due to the inhibition of
glycolysis [18,19]. It is also important for athletes to replenish the glycogen stores during postexercise training to provide sufficient energy for the next training session or competition. For rapid
replenishment of glycogen stores, a high-carbohydrate diet can be effective [19,20]. Intake of protein
along with carbohydrate can be more effective for the rapid replenishment of muscle glycogen after
exercise compared with carbohydrate supplements alone[21,22].
When prolonged exercise will be performed, such as a marathon, taking carbohydrates immediately
before or during exercise is also an effective method of improving endurance. Under such conditions,
it is desirable for the athlete to ingest monosaccharides or oligosaccharides, because these are
rapidly absorbed and transported to the peripheral tissues. On the other hand, intake of
carbohydrates inhibits the degradation of fat, which is another energy substrate, by stimulating insulin
secretion [23,24]. This leads to impairment of energy production via lipid metabolism and accelerates
glycolysis as alternate energy production pathway. As a result, the consumption of muscle glycogen
will increase, and the intramuscular pH will decrease due to increased lactic acid production, which
may lead to impairment of muscle contraction. Therefore, it is necessary to ingest carbohydrates that
will not inhibit lipid metabolism. It has been suggested that supplements containing fructose, which
cause less stimulation of insulin secretion and are unlikely to inhibit lipolysis, rather than common
carbohydrates such as glucose and sucrose, may be better for improving endurance [25].
Furthermore, simultaneous intake of citrate can be expected to promote energy consumption from
lipids through inhibition of glycolysis [26]. This will spare glycogen and inhibit lactic acid production, so
that the weakening of muscle contraction will be delayed. An amino acid, arginine, has been reported
to modulate hormones that control the blood glucose level without inhibiting lipid metabolism, and to
delay glycogen depletion during exercise [26,27]. Therefore, intake of both citrate and arginine along
with carbohydrates that cause little stimulation of insulin secretion before or during exercise may be
an effective way to improve energy metabolism and to supply the optimum energy sources for
prolonged exercise.
If there is a shift from predominantly glucose-based energy consumption to lipid-based energy
consumption, this may lead to improvement of endurance by maintaining glycogen stores and
inhibiting the decrease of intramuscular pH that results from generation of lactate during exercise.
Several authors have reported about various factors that can stimulate lipid metabolism, although
there is insufficient evidence about their efficacy. Carnitine is an intracellular enzyme that is required
for fatty acid transport across the mitochondrial membrane into the mitochondria, and it promotes the
β-oxidation of fatty acids [28,29]. Carnitine supplementation is expected to activate lipid metabolism in
the skeletal muscles, and to also achieve the sparing of glycogen stores. In persons performing
aerobic training, intake of 2–4 g of carnitine before exercise or on a daily basis was reported to
increase the maximum oxygen consumption (anaerobic threshold) and also inhibited the
accumulation of lactate after exercise [30,31]. The effect of caffeine on endurance has also been
studied. Caffeine inhibits phosphotidiesterase by promoting catecholamine release and increases
hormone-sensitive lipase (HSL) activity, which leads to an increase of circulating free fatty acids and
further improvement of endurance [32,33]. Capsaicin, obtained from hot red peppers, is likely to
enhance fat metabolism by altering the balance of lipolytic hormones and promoting fat oxidation in
skeletal muscle [34,35].
Enhancement of Muscle Strength
It is well known that the strength of a muscle is generally proportional to its cross-sectional area, and
it is necessary to increase muscle bulk in order to enhance strength. Muscle tissue is mainly
composed of proteins (such actin and myosin) and water, and it is important to increase the protein
content by modulating protein metabolism when increasing muscle bulk. In other words, muscle bulk
and strength can be increased by promoting protein synthesis or by inhibiting protein degradation.
Resistance exercise is aimed at increasing muscle bulk, and it enhances the secretion and production
of growth hormone and various growth factors [36]. Thus, resistance exercise promotes protein
synthesis and an increment of muscle mass more strongly compared with aerobic exercise. In order
to maximize the effect of resistance exercise, it is important to maintain the muscular pool and blood
levels of various amino acids that are substrates for the synthesis of muscle proteins. For this
purpose, it is necessary to maintain a positive nitrogen balance by increasing the dietary protein
intake. Several studies have shown that protein requirements of strength training athletes are higher
than those of sedentary individuals [37-40]. The daily recommended protein intake is estimated to be
1.4 – 1.8 g/kg for performing resistance exercise when the intake of calories and carbohydrate is
adequate [41,42] although 1.0 g/kg of protein is generally sufficient for endurance athletes excluding
an elite minority [43]. It may be difficult to maintain such a high dietary protein intake, but ingestion of
protein supplements can be effective. A wide variety of raw materials are utilized for the production of
powdered protein supplements, and products derived from soy beans, eggs, or whey (milk protein)
are commercially available. All of these products contain a good balance of essential amino acids,
and often achieve an amino acid score of 100. In particular, whey protein is believed to be an ideal
source for building muscles, since such protein is easily digested and absorbed, resulting in a rapid
increase in the blood level of amino acids [44,45]. In addition, branched-chain amino acids and
glutamine, which promote the synthesis of muscle protein, have a high content in whey
protein [44,46]. Not only the amount of protein intake, but also the timing of intake are important for
building muscles efficiently. Eating a meal immediately after resistance exercise may contribute to a
greater increase of muscle mass compared with ingesting a meal several hours later [47-49]. Also,
intake of carbohydrates with protein can accelerate the synthesis of muscle protein via the actions of
insulin, which increases protein synthesis and inhibits its catabolism [50,51].
In addition, it has been reported that the intake of amino acids and peptides is beneficial. Free amino
acids and peptides do not need to be digested, so rapid absorption can be expected. Amino acids are
not only utilized for the synthesis of muscle protein, and some of these molecules also exert a variety
of physiological effects. Attention has been focused on the effects of branched-chain amino acids
(BCAAs), including valine, leucine, and isoleucine, which are known to have a relatively high content
in both muscle proteins and food proteins [52]. Most amino acids are metabolized in the liver, but
BCAAs are metabolized in the muscles via special processes [52,53]. BCAAs are utilized as energy
substrates and their oxidation is enhanced during exercise by activation of branched-chain-α-keto
acid dehydrogenase (BCKDH) complex [54]. Furthermore, BCAAs modulate muscle protein
metabolism to promote the synthesis and inhibit the degradation of proteins [54-56], resulting in an
anabolic effect on the muscles. Glutamine has also been reported to promote muscle growth by
inhibiting protein degradation [57-59]. It is the most abundant free amino acid in muscle tissue [60]
and its intake leads to an increase of myocyte volume, resulting in stimulation of muscle growth [5759]. Glutamine is also found at relatively high concentrations in many other human tissues and has an
important homeostatic role [60]. Therefore, during catabolic states such as exercise, glutamine is
released from skeletal muscle into the plasma to be utilized for maintenance of the glutamine level in
other tissues [61]. Arginine is a precursor of nitric oxide and creatine, and its injection promotes the
secretion of growth hormone [62,63], which may lead to an increase of muscle mass and strength.
Although the effect of oral arginine on protein synthesis is equivocal, recent studies have indicated
that combined intake of arginine with other compounds improves exercise performance [64-66].
Various other food components have also been studied to determine their effects on muscle strength
and mass. A meta-analysis of studies done between 1967 and 2001 supported the use of two
supplements, creatine and β-hydroxy-β-methylbutyrate (βHMB), to augment lean body mass and
strength when performing resistance exercise [67]. The human body contains more than 100 g of
creatine, almost all of which is stored in the skeletal muscles as creatine phosphate. This is used to
produce ATP by degradation to creatine under anaerobic conditions, so improvement of anaerobic
metabolism can be expected by increasing the stores of creatine. Intake of creatine also stimulates
water retention and protein synthesis [68,69]. It has been reported that the intake of ≥3 g/day of
creatine increases the intramuscular content of creatine phosphate and improves endurance,
especially during activities with a high power output (such as short distance running or resistance
exercise), as well as improving muscle strength [70-72]. In addition, it has been reported that intake of
creatine accelerates the increase of lean body mass and muscle strength during resistance
training [72-74]. βHMB is a metabolite of the branched-chain amino acid leucine, and it increases
muscle bulk by inhibiting the degradation of protein via an influence on the metabolism of branchedchain amino acids [75,76]. It has been reported that intake of 1.5 to 3.0 g/day of βHMB for 3 to 8
weeks achieved a greater increase of muscle mass and power compared with the intake of
placebo [77-79].
Prevention of Injury and Fatigue
Strenuous physical activity or unaccustomed exercise causes injury to the muscles, release of
muscular protein, and muscle pain. The mechanism underlying delayed the muscle damage after
intense physical activity is not fully understood, but it has been suggested that such delayed injury is
due to an inflammatory reaction induced by phagocyte infiltration that is triggered by excessive
mechanical stress [80,81], an increased intracellular Ca2+ concentration [82,83], and oxidative
stress [84]. There are several reports which examined whether antioxidants attenuate the muscle
damage since a significant increase of oxidative products is noted in the exercised muscles and in the
blood in post-exercise parallel to other parameters of delayed-onset muscle damage. Oxidative injury
after acute exercise can be prevented by the intake of antioxidants, such as vitamins C and E,
carotenoids, or polyphenols, not only during exercise, but also on a daily basis[84-91]. In contrast,
several studies have indicated that antioxidants do not affect muscle damage and the inflammatory
response caused by strenuous exercise [92-94]. One possibility on reason of the different results is
that the effect of antioxidants is likely to be differences of exercise conditions, such intensity of
mechanical stress and oxygen uptake. Reactive oxygen species (ROS) could be related to initiation of
the muscle damage. ROS are generated from mitochondria and endothelium during exercise via
elevation of the oxygen uptake of myocytes and ischemia-reperfusion process, which leads to
invasion of phagocytes into the muscles after exercise via redox-sensitive inflammatory cascade.
Therefore, the inflammatory response may be inhibited if ROS production during exercise is
decreased just in large contribution of ROS on the initiation of muscle damage such endurance
prolonged exercise not resistance exercise. Additionally, it would be better to take several
antioxidants at the same time because different organelles are affected by each kind of antioxidant,
such water-soluble or lipid-soluble compounds, and they can provide electrons to each other to
prevent a change to pro-oxidant status.
Glucosamine and chondroitin are substances that protect the joints. Glucosamine is an amino acid
synthesized in the body that is a component of synovial fluid, tendons, and ligaments in the joints.
Chondroitin is mainly contained in cartilage, tendons, and the connective tissues of the skin, and
plays an important role as a shock absorber due to its hygroscopic action. Supplementary oral intake
of these substances is suggested to be effective for preventing or promoting recovery from
osteoarthritis associated with exercise and aging [95,96] while the effect of supplementation in
exercise is not clear.
There are various kinds of factors expressing fatigue condition induced by exercise such glycogen
depletion and accumulation of lactic acid during exercise, and hyperactivation of sympathetic nerve in
post-exercise. As mentioned above, recovery of glycogen storage in muscle is promoted by highcarbohydrate diet. At the same time, it is more effective to take a factor with an inhibitory effect on
glycolysis such as citrate and consider the timing of carbohydrate intake. Also, lactate accumulation in
muscle inhibits capacity of muscular contraction associated with pH decrease in muscle, which could
be one of fatigue conditions. Thus, dietary supplementation regulating production or clearance lactate
may be effective. Dipeptides that are abundant in skeletal muscle, carnosine and anserine, are known
to have a pH-buffering effect [97]. Supplementation of these dipeptides is also possible to inhibit the
decline of intramuscular pH by exercise via the buffering action of these dipeptides [98-100].
Maintenance of Immunity
It is generally believed that moderate exercise enhances immunocompetence and is effective for the
prevention of inflammatory diseases, infection, and cancer, while excessive physical activity leads to
immunosuppression and an increase of inflammatory and allergic disorders [101-103]. Susceptibility
to infections following excessive physical activity is ascribed to an increase in the production of
immunosuppressive factors such as adrenocortical hormones and anti-inflammatory cytokines,
leading to a decrease in the number and activity of circulating natural killer cells and T cells as well as
a lower IgA concentration in the saliva [104]. Therefore, athletes performing high-intensity training are
exposed to the risk of impaired immunocompetence. Intake of carbohydrates during prolonged
exercise at submaximal intensity attenuates the increase of plasma cortisol and cytokine levels after
exercise, which could lead to the inhibition of immunosuppression [105-107]. Vitamin C and vitamin E
have actions that promote immunity, and are essential for T cell differentiation and for maintenance of
T cell function [104,108,109]. However, there is limited evidence about the effects of vitamins
supplementation on immune function in relation to exercise. Glutamine is an important energy source
for lymphocytes, macrophages, and neutrophils, and is also an essential amino acid for the
differentiation and growth of these cells [57,110]. Intense exercise decreases the plasma glutamine
concentration and this may be related to immunosuppression [111]. Castell et al. [112] reported that
athletes who ingested glutamine had a lower infection rate after a marathon compared with the
placebo group. They also demonstrated that intake of glutamine resulted in an increase of the Thelper/T-suppressor cell ratio [113]. Furthermore, glutamine enhances the activity of intestinal
enterobacteria and inhibits the production of cytokines involved in inflammation or
immunosuppression [110].
Conclusion
Due to a social background that includes changes of dietary habits, an aging population, and
increased medical costs, people have shown a growing interest in health and have come to expect
complex and diverse actions of foods. In recent years, various food factors that fulfill such
requirements have been evaluated scientifically to determine whether they are any physiological
effects like prevention of diseases. In the sports market, a variety of functional foods are available, but
among these functional foods, some have not clearly demonstrated any efficacy and others are
advertised with inappropriate and exaggerated claims, so consumers are often confused. Some of the
food components described in this article should be studied further because of differing views with
regard to their efficacy in different reports. Furthermore, the effectiveness of the components may
differ according to gender, between individuals, and with the mode of ingestion, so that the optimum
method of intake the quantity and quality of foods to be ingested, and the timing of their intake need to
be established in accordance with the purpose of using each food or food component, after
understanding the physiological changes by exercise. In the future, guidelines for the use and
evaluation system of sports functional foods should be established with backing by clear scientific
evidence related to the individual foods.
Table 1. Exercise and functional foods.
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Sports Nutrition Overview
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Sports Nutrition Overview
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Peak Nutritionals Whey Protein Claims – Supporting Literature
Whey Protein – Muscle Protein Synthesis
Am J Physiol Endocrinol Metab. 2012 Apr 15;302(8):E992-9. doi: 10.1152/ajpendo.00517.2011. Epub
2012 Feb 14.
Amino acid absorption and subsequent muscle protein accretion following graded intakes of
whey protein in elderly men.
Pennings B1, Groen B, de Lange A, Gijsen AP, Zorenc AH, Senden JM, van Loon LJ.
Author information
Abstract
Whey protein ingestion has been shown to effectively stimulate postprandial muscle protein accretion
in older adults. However, the impact of the amount of whey protein ingested on protein digestion and
absorption kinetics, whole body protein balance, and postprandial muscle protein accretion remains to
be established. We aimed to fill this gap by including 33 healthy, older men (73 ± 2 yr) who were
randomly assigned to ingest 10, 20, or 35 g of intrinsically l-[1-¹³C]phenylalanine-labeled whey protein
(n = 11/treatment). Ingestion of labeled whey protein was combined with continuous intravenous l[ring-²H₅]phenylalanine and l-[ring-²H₂]tyrosine infusion to assess the metabolic fate of whey proteinderived amino acids. Dietary protein digestion and absorption rapidly increased following ingestion of
10, 20, and 35 g whey protein, with the lowest and highest (peak) values observed following 10 and
35 g, respectively (P < 0.05). Whole body net protein balance was positive in all groups (19 ± 1, 37 ±
2, and 58 ± 2 μmol/kg), with the lowest and highest values observed following ingestion of 10 and 35
g, respectively (P < 0.05). Postprandial muscle protein accretion, assessed by l-[1-¹³C]phenylalanine
incorporation in muscle protein, was higher following ingestion of 35 g when compared with 10 (P <
0.01) or 20 (P < 0.05) g. We conclude that ingestion of 35 g whey protein results in greater amino acid
absorption and subsequent stimulation of de novo muscle protein synthesis compared with the
ingestion of 10 or 20 g whey protein in healthy, older men.
Med Sci Sports Exerc. 2004 Dec;36(12):2073-81.
Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise.
Tipton KD1, Elliott TA, Cree MG, Wolf SE, Sanford AP, Wolfe RR.
Author information
Abstract
PURPOSE:
Determination of the anabolic response to exercise and nutrition is important for individuals who may
benefit from increased muscle mass. Intake of free amino acids after resistance exercise stimulates
net muscle protein synthesis. The response of muscle protein balance to intact protein ingestion after
exercise has not been studied. This study was designed to examine the acute response of muscle
protein balance to ingestion of two different intact proteins after resistance exercise.
METHODS:
Healthy volunteers were randomly assigned to one of three groups. Each group consumed one of
three drinks: placebo (PL; N = 7), 20 g of casein (CS; N = 7), or whey proteins (WH; N = 9).
Volunteers consumed the drink 1 h after the conclusion of a leg extension exercise bout. Leucine and
phenylalanine concentrations were measured in femoral arteriovenous samples to determine balance
across the leg.
RESULTS:
Arterial amino acid concentrations were elevated by protein ingestion, but the pattern of appearance
was different for CS and WH. Net amino acid balance switched from negative to positive after
ingestion of both proteins. Peak leucine net balance over time was greater for WH (347 +/- 50
nmol.min(-1).100 mL(-1) leg) than CS (133 +/- 45 nmol.min(-1).100 mL(-1) leg), but peak
phenylalanine balance was similar for CS and WH. Ingestion of both CS and WH stimulated a
significantly larger net phenylalanine uptake after resistance exercise, compared with the PL (PL -5
+/- 15 mg, CS 84 +/- 10 mg, WH 62 +/- 18 mg). Amino acid uptake relative to amount ingested was
similar for both CS and WH (approximately 10-15%).
CONCLUSIONS:
Acute ingestion of both WH and CS after exercise resulted in similar increases in muscle protein net
balance, resulting in net muscle protein synthesis despite different patterns of blood amino acid
responses.
Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E231-42. doi: 10.1152/ajpendo.00513.2010. Epub
2010 Nov 2.
Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: effect of
resistance exercise and protein ingestion.
Reitelseder S1, Agergaard J, Doessing S, Helmark IC, Lund P, Kristensen NB, Frystyk J, Flyvbjerg
A, Schjerling P, van Hall G, Kjaer M, Holm L.
Author information
Abstract
Muscle protein turnover following resistance exercise and amino acid availability are relatively well
described. By contrast, the beneficial effects of different sources of intact proteins in relation to
exercise need further investigation. Our objective was to compare muscle anabolic responses to a
single bolus intake of whey or casein after performance of heavy resistance exercise. Young male
individuals were randomly assigned to participate in two protein trials (n = 9) or one control trial (n =
8). Infusion of l-[1-(13)C]leucine was carried out, and either whey, casein (0.3 g/kg lean body mass),
or a noncaloric control drink was ingested immediately after exercise. l-[1-(13)C]leucine-labeled whey
and casein were used while muscle protein synthesis (MPS) was assessed. Blood and muscle tissue
samples were collected to measure systemic hormone and amino acid concentrations, tracer
enrichments, and myofibrillar protein synthesis. Western blots were used to investigate the Akt
signaling pathway. Plasma insulin and branched-chain amino acid concentrations increased to a
greater extent after ingestion of whey compared with casein. Myofibrillar protein synthesis was equally
increased 1-6 h postexercise after whey and casein intake, both of which were higher compared with
control (P < 0.05). Phosphorylation of Akt and p70(S6K) was increased after exercise and protein
intake (P < 0.05), but no differences were observed between the types of protein except for total 4EBP1, which was higher after whey intake than after casein intake (P < 0.05). In conclusion, whey and
casein intake immediately after resistance exercise results in an overall equal MPS response despite
temporal differences in insulin and amino acid concentrations and 4E-BP1.
Whey Protein – Lean Muscle Mass
J Strength Cond Res. 2006 Aug;20(3):643-53.
The effects of protein and amino acid supplementation on performance and training
adaptations during ten weeks of resistance training.
Kerksick CM1, Rasmussen CJ, Lancaster SL, Magu B, Smith P, Melton C, Greenwood M, Almada
AL, Earnest CP, Kreider RB.
Author information
Abstract
The purpose of this study was to examine the effects of whey protein supplementation on body
composition, muscular strength, muscular endurance, and anaerobic capacity during 10 weeks of
resistance training. Thirty-six resistance-trained males (31.0 +/- 8.0 years, 179.1 +/- 8.0 cm, 84.0 +/12.9 kg, 17.8 +/- 6.6%) followed a 4 days-per-week split body part resistance training program for 10
weeks. Three groups of supplements were randomly assigned, prior to the beginning of the exercise
program, in a double-blind manner to all subjects: 48 g per day (g.d(-1)) carbohydrate placebo (P), 40
g.d(-1) of whey protein + 8 g.d(-1) of casein (WC), or 40 g.d(-1) of whey protein + 3 g.d(-1) branchedchain amino acids + 5 g.d(-1) L-glutamine (WBG). At 0, 5, and 10 weeks, subjects were tested for
fasting blood samples, body mass, body composition using dual-energy x-ray absorptiometry (DEXA),
1 repetition maximum (1RM) bench and leg press, 80% 1RM maximal repetitions to fatigue for bench
press and leg press, and 30-second Wingate anaerobic capacity tests. No changes (p > 0.05) were
noted in all groups for energy intake, training volume, blood parameters, and anaerobic capacity. WC
experienced the greatest increases in DEXA lean mass (P = 0.0 +/- 0.9; WC = 1.9 +/- 0.6; WBG = -
0.1 +/- 0.3 kg, p < 0.05) and DEXA fat-free mass (P = 0.1 +/- 1.0; WC = 1.8 +/- 0.6; WBG = -0.1 +/0.2 kg, p < 0.05). Significant increases in 1RM bench press and leg press were observed in all groups
after 10 weeks. In this study, the combination of whey and casein protein promoted the greatest
increases in fat-free mass after 10 weeks of heavy resistance training. Athletes, coaches, and
nutritionists can use these findings to increase fat-free mass and to improve body composition during
resistance training.
Metabolism. 2005 Feb;54(2):151-6.
The effect of resistance training combined with timed ingestion of protein on muscle fiber size
and muscle strength.
Andersen LL1, Tufekovic G, Zebis MK, Crameri RM, Verlaan G, Kjaer M, Suetta C, Magnusson
P, Aagaard P.
Author information
Abstract
Acute muscle protein metabolism is modulated not only by resistance exercise but also by amino
acids. However, less is known about the long-term hypertrophic effect of protein supplementation in
combination with resistance training. The present study was designed to compare the effect of 14
weeks of resistance training combined with timed ingestion of isoenergetic protein vs carbohydrate
supplementation on muscle fiber hypertrophy and mechanical muscle performance. Supplementation
was administered before and immediately after each training bout and, in addition, in the morning on
nontraining days. Muscle biopsy specimens were obtained from the vastus lateralis muscle and
analyzed for muscle fiber cross-sectional area. Squat jump and countermovement jump were
performed on a force platform to determine vertical jump height. Peak torque during slow (30 degrees
s-1) and fast (240 degrees s-1) concentric and eccentric contractions of the knee extensor muscle
was measured in an isokinetic dynamometer. After 14 weeks of resistance training, the protein group
showed hypertrophy of type I (18% +/- 5%; P < .01) and type II (26% +/- 5%; P < .01) muscle fibers,
whereas no change above baseline occurred in the carbohydrate group. Squat jump height increased
only in the protein group, whereas countermovement jump height and peak torque during slow
isokinetic muscle contraction increased similarly in both groups. In conclusion, a minor advantage of
protein supplementation over carbohydrate supplementation during resistance training on mechanical
muscle function was found. However, the present results may have relevance for individuals who are
particularly interested in gaining muscle size.
Abstract
Effect of Dietary Protein Intake on Diet-Induced Thermogenesis During Overfeeding
Elizabeth Frost Baton Rouge Louisiana, Leanne Redman Baton Rouge Louisiana, George Bray Baton
Rouge Louisiana
Background: High protein diets for weight loss are popular and data suggests protein-mediated
effects on satiety and thermogenesis may be potential mechanisms. This study determined if a
prolonged change in dietary protein intake during overfeeding can modify the thermogenic response
to a standard meal.
Methods: Sixteen healthy individuals were randomized to overfeeding diets containing low (5%
energy, n=6), normal (15% energy, n=5), or high (25% energy, n=5) protein for 8 weeks while living
on a metabolic ward. Diet-induced thermogenesis (DIT) was measured over 4 hours by indirect
calorimetry following a standard meal (40% of energy, 15% protein) or a breakfast meal specific to the
study diet measured by a portable metabolic cart or in a whole room calorimeter, respectively. The
area under the curve (AUC) for energy expenditure (EE) and substrate oxidation and DIT as percent
of total EE were calculated.
Results: As expected, the AUC for EE following the overfeeding breakfast specific to each study
group was significantly associated with grams of protein (r2=0.32, P=0.02) with the AUC EE
significantly increased in the high protein diet versus the low protein diet (HP: 178578, LP: 77278,
kcal, P=0.05). However, DIT in response to a standard meal with the 15% protein was not associated
with prolonged exposure to high energy intake (r2=0.12, P=0.16).
Conclusions: DIT is related to dietary protein but prolonged exposure to high energy diets does not
alter the thermogenic response to a standard meal suggesting the DIT is likely under acute regulation
and not involved in adaptive thermogenesis.
Whey Protein – Ghrelin and Appetite
J Nutr. 2011 Aug;141(8):1489-94. doi: 10.3945/jn.111.139840. Epub 2011 Jun 15.
Whey protein but not soy protein supplementation alters body weight and composition in freeliving overweight and obese adults.
Baer DJ1, Stote KS, Paul DR, Harris GK, Rumpler WV, Clevidence BA.
Author information
Abstract
A double-blind, randomized clinical trial was conducted to determine the effect of consumption of
supplemental whey protein (WP), soy protein (SP), and an isoenergetic amount of carbohydrate
(CHO) on body weight and composition in free-living overweight and obese but otherwise healthy
participants. Ninety overweight and obese participants were randomly assigned to 1 of 3 treatment
groups for 23 wk: 1) WP; 2) SP (each providing ~56 g/d of protein and 1670 kJ/d); or 3) an
isoenergetic amount of CHO. Supplements were consumed as a beverage twice daily. Participants
were provided no dietary advice and continued to consume their free-choice diets. Participants' body
weight and composition data were obtained monthly. Dietary intake was determined by 24-h dietary
recalls collected every 10 d. After 23 wk, body weight and composition did not differ between the
groups consuming the SP and WP or between SP and CHO; however, body weight and fat mass of
the group consuming the WP were lower by 1.8 kg (P < 0.006) and 2.3 kg (P < 0.005), respectively,
than the group consuming CHO. Lean body mass did not differ among any of the groups. Waist
circumference was smaller in the participants consuming WP than in the other groups (P < 0.05).
Fasting ghrelin was lower in participants consuming WP compared with SP or CHO. Through yetunknown mechanisms, different sources of dietary protein may differentially facilitate weight loss and
affect body composition. Dietary recommendations, especially those that emphasize the role of
dietary protein in facilitating weight change, should also address the demonstrated clinical potential of
supplemental WP.
Whey Protein – Phospholipids
Phospholipids and sports performance
Ralf Jäger1*†, Martin Purpura1† and Michael Kingsley2†
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*Corresponding author: Ralf Jäger [email protected]
† Equal contributors
Author Affiliations
1Increnovo
LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
2Department
of Sports Science, University of Wales Swansea, Singleton Park, Swansea, SA2
8PP, UK
Abstract
Phospholipids are essential components of all biological membranes. Phosphatidylcholine (PC) and
Phosphatidylserine (PS) are Phosphatidyl-phospholipids that are required for normal cellular structure
and function. The participation in physical activity often challenges a variety of physiological systems;
consequently, the ability to maintain normal cellular function during activity can determine sporting
performance. The participation in prolonged intense exercise has been shown to reduce circulatory
choline concentrations in some individuals. As choline is a pre-cursor to the neurotransmitter
Acetylcholine, this finding has encouraged researchers to investigate the hypothesis that
supplementation with PC (or choline salts) could enhance sporting performance. Although the
available data that evaluates the effects of PC supplementation on performance are equivocal, acute
oral supplementation with PC (~0.2 g PC per kg body mass) has been demonstrated to improve
performance in a variety of sporting activities where exercise has depleted circulatory choline
concentrations. Short term oral supplementation with soy-derived PS (S-PS) has been reported to
attenuate circulating cortisol concentrations, improve perceived well-being, and reduce perceived
muscle soreness after exercise. More recently, short term oral supplementation (750 mg per day of SPS for 10 days) has been demonstrated to improve exercise capacity during high intensity cycling and
tended to increase performance during intermittent running. Although more research is warranted to
determine minimum dietary Phospholipid requirements for optimal sporting performance, these
findings suggest that some participants might benefit from dietary interventions that increase the
intakes of PC and PS.
Whey Protein and Glutamine
Br J Sports Med 2010;44:i43 doi:10.1136/bjsm.2010.078725.143
•
6. Sports Nutrition
Assessment of the effect of L-glutamine supplementation on DOMS
1.
Somayeh Namdar Tajari,
2.
Mona Rezaee,
3.
Naghme Gheidi
+Author Affiliations
1.
Islamic Azad University, Saveh Branch, Saveh, Iran
Abstract
Glutamine is an amino acid and is not considered one of the eight essential aminos. Amino acid
supplementation outspreaded to enhancing athletic performance, preparation, removal fatigue and
minimising risk of injures. Delayed onset muscle soreness (DOMS) is result of a combination of
unaccustomed muscle contraction (especially lengthening of the muscle under load) and poor motor
neuron recruitment. This study investigated the effect of L-glutamine supplementation on DOMS after
30 min ergometric exercise by comparing two metabolic enzymes (aldolase and creatine kinase) and
hip flexors range of motion. Experimental double blind design was used. This study included 20 nonathletic girl with 22.8±2.6 years old and 21.45±3.1 body mass index. The subjects randomise to
glutamine and placebo supplementations. The supplement group was ingested 4 weeks, three times
in week and twice a day (5 g per time). The control group use placebo same as experimental group.
analyses of variance and t test use for data analyses. Aldolase increased 36 h after activity than after
activity time in experimental group, but in control group it was reverted. There is a significant
difference in aldolase level between control and experimental group (p> 0.05). The creatine kinase
increased significantly in 36 h after activity than after activity time in experimental group. Range of
motion of hip joint decreased in T3 in both of them significantly, but it was recovered for experimental
group 36 h after activity. These results suggest that L-glutamine supplementation attenuates DOMS
effects, muscle damage and downfall of performance in flexor of hip.
Med J Aust. 1995 Jan 2;162(1):15-8.
Depression of plasma glutamine concentration after exercise stress and its possible influence
on the immune system.
Keast D1, Arstein D, Harper W, Fry RW, Morton AR.
Author information
Abstract
OBJECTIVE:
To determine whether plasma glutamine levels can be used as an indicator of exercise-induced
stress, and to consider the possible effects of low plasma glutamine concentrations on the immune
system.
METHODS:
We used two exercise regimens: in Trial 1 seven male subjects were randomly stressed on a treadmill
at 0, 30%, 60%, 90% and 120% of their maximal oxygen uptake (VO2max); in Trial 2 five highly
trained male subjects underwent intensive interval training sessions twice daily for ten days, followed
by a six-day recovery period.
RESULTS:
Plasma glutamine concentrations decreased significantly from an average of 1244 +/- 121 mumol/L to
702 +/- 101 mumol/L after acute exercise at 90% VO2max (P < 0.05) and to 560 +/- 79 mumol/L at
120% VO2max (P < 0.001). Four of the five subjects showed reduced plasma glutamine
concentrations by Day 6 of the overload training trial, with all subjects displaying significantly lower
glutamine levels by Day 11. However, glutamine levels showed a variable rate of recovery over the
six-day recovery period, with two subjects' levels remaining low by Day 16.
CONCLUSIONS:
Reduced plasma glutamine concentrations may provide a good indication of severe exercise stress.
Linda M. Castell
,
Eric A. Newsholme, DSC
University Department of Biochemistry, Oxford, United Kingdom
DOI: http://dx.doi.org/10.1016/S0899-9007(97)83036-5
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•
Abstract
References
Abstract
Athletes undergoing intense, prolonged training or participating in endurance races suffer an
increased risk of infection due to apparent immunosuppression. Glutamine is an important fuel for
some cells of the immune system and may have specific immunostimulatory effects. The plasma
glutamine concentration is lower after prolonged, exhaustive exercise: this may contribute to
impairment of the immune system at a time when the athlete may be exposed to opportunistic
infections. The effects of feeding glutamine was investigated both at rest in sedentary controls and
after exhaustive exercise in middle-distance, marathon and ultra-marathon runners, and elite rowers,
in training and competition. Questionnaires established the incidence of infection for 7 d after
exercise: infection levels were highest in marathon and ultra-marathon runners, and in elite male
rowers after intensive training. Plasma glutamine levels were decreased by ∼20% 1 h after marathon
running. A marked increase in numbers of white blood cells occurred immediately after exhaustive
exercise, followed by a decrease in the numbers of lymphocytes. The provision of oral glutamine after
exercise appeared to have a beneficial effect on the level of subsequent infections. In addition, the
ratio of T-helper/T-suppressor cells appeared to be increased in samples from those who received
glutamine, compared with placebo.
European Journal of Applied Physiology and Occupational Physiology
June 1996, Volume 73, Issue 5, pp 488-490
Does glutamine have a role in reducing infections in athletes?
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•
•
L. M. Castell,
E. A. Newsholme,
J. R. Poortmans
Abstract
There is an increased risk of infections in athletes undertaking prolonged, strenuous exercise. There
is also some evidence that cells of the immune system are less able to mount a defence against
infections after such exercise. The level of plasma glutamine, an important fuel for cells of the immune
system, is decreased in athletes after endurance exercise: this may be partly responsible for the
apparent immunosuppression which occurs in these individuals. We monitored levels of infection in
more than 200 runners and rowers. The levels of infection were lowest in middle-distance runners,
and highest in runners after a full or ultra-marathon and in elite rowers after intensive training. In the
present study, athletes participating in different types of exercise consumed two drinks, containing
either glutamine (Group G) or placebo (Group P) immediately after and 2 h after exercise. They
subsequently completed questionnaires (n = 151) about the incidence of infections during the 7 days
following the exercise. The percentage of athletes reporting no infections was considerably higher in
Group G (81%,n= 72) than in Group P (49%,n = 79,p<0.001).
Sports Medicine
April 2003, Volume 33, Issue 5, pp 323-345
Date: 23 Sep 2012
Glutamine Supplementation In Vitro andIn Vivo, in Exercise and in Immunodepression
•
Linda M. Castell
Abstract
In situations of stress, such as clinical trauma, starvation or prolonged, strenuous exercise, the
concentration of glutamine in the blood is decreased, often substantially. In endurance athletes this
decrease occurs concomitantly with relatively transient immunodepression. Glutamine is used as a
fuel by some cells of the immune system. Provision of glutamine or a glutamine precursor, such as
branched chain amino acids, has been seen to have a beneficial effect on gut function, on morbidity
and mortality, and on some aspects of immune cell function in clinical studies. It has also been seen
to decrease the self-reported incidence of illness in endurance athletes. So far, there is no firm
evidence as to precisely which aspect of the immune system is affected by glutamine feeding during
the transient immunodepression that occurs after prolonged, strenuous exercise. However, there is
increasing evidence that neutrophils may be implicated. Other aspects of glutamine and glutamine
supplementation are also addressed.