J Nutr. 2008 Nov;138(11):2198-204.

Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans

Howarth KR, Moreau NA, Phillips SM, Gibala MJ.

Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.

Coingestion of protein with carbohydrate (CHO) during recovery from exercise can affect muscle glycogen synthesis, particularly if CHO intake is suboptimal. Another potential benefit of protein feeding is an increased synthesis rate of muscle proteins, as is well documented after resistance exercise. In contrast, the effect of nutrient manipulation on muscle protein kinetics after aerobic exercise remains largely unexplored. We tested the hypothesis that ingesting protein with CHO after a standardized 2-h bout of cycle exercise would increase mixed muscle fractional synthetic rate (FSR) and whole body net protein balance (WBNB) vs. trials matched for total CHO or total energy intake. We also examined whether postexercise glycogen synthesis could be enhanced by adding protein or additional CHO to a feeding protocol that provided 1.2 g CHO x kg(-1) x h(-1), which is the rate generally recommended to maximize this process. Six active men ingested drinks during the first 3 h of recovery that provided either 1.2 g CHO.kg(-1).h(-1) (L-CHO), 1.2 g CHO + 0.4 g protein x kg(-1) x h(-1) (PRO-CHO), or 1.6 g CHO x kg(-1) x h(-1) (H-CHO) in random order. Based on a primed constant infusion of l-[ring-(2)H(5)]phenylalanine, analysis of biopsies (vastus lateralis) obtained at 0 and 4 h of recovery showed that muscle FSR was higher (P < 0.05) in PRO-CHO (0.09 +/- 0.01%/h) vs. both L-CHO (0.07 +/- 0.01%/h) and H-CHO (0.06 +/- 0.01%/h). WBNB assessed using [1-(13)C]leucine was positive only during PRO-CHO, and this was mainly attributable to a reduced rate of protein breakdown. Glycogen synthesis rate was not different between trials. We conclude that ingesting protein with CHO during recovery from aerobic exercise increased muscle FSR and improved WBNB, compared with feeding strategies that provided CHO only and were matched for total CHO or total energy intake. However, adding protein or additional CHO to a feeding strategy that provided 1.2 g CHO x kg(-1) x h(-1) did not further enhance glycogen resynthesis during recovery.

Am J Clin Nutr. 2000 Jul;72(1):106-11.

Maximizing postexercise muscle glycogen synthesis: carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures.

Van Loon LJ, Saris WH, Kruijshoop M, Wagenmakers AJ.

From the Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Human Biology, Maastricht University, Maastricht, The Netherlands. L.vanLoon@hb.unimaas.nl

BACKGROUND: Postexercise muscle glycogen synthesis is an important factor in determining the time needed to recover from prolonged exercise. OBJECTIVE: This study investigated whether an increase in carbohydrate intake, ingestion of a mixture of protein hydrolysate and amino acids in combination with carbohydrate, or both results in higher postexercise muscle glycogen synthesis rates than does ingestion of 0.8 g*kg(-)(1)*h(-)(1) carbohydrate, provided at 30-min intervals. DESIGN: Eight trained cyclists visited the laboratory 3 times, during which a control beverage and 2 other beverages were tested. After the subjects participated in a strict glycogen-depletion protocol, muscle biopsy samples were collected. The subjects received a beverage every 30 min to ensure ingestion of 0.8 g carbohydrate*kg(-)(1)*h(-)(1) (Carb trial), 0.8 g carbohydrate*kg(-)(1)*h(-)(1) plus 0.4 g wheat protein hydrolysate plus free leucine and phenylalanine*kg(-)(1)*h(-)(1) (proven to be highly insulinotropic; Carb + Pro trial), or 1.2 g carbohydrate*kg(-)(1)*h(-)(1) (Carb + Carb trial). After 5 h, a second biopsy was taken. RESULTS: Plasma insulin responses in the Carb + Pro and Carb + Carb trials were higher than those in the Carb trial (88 +/- 17% and 46 +/- 18%; P < 0.05). Muscle glycogen synthesis was higher in both trials than in the Carb trial (35. 4 +/- 5.1 and 44.8 +/- 6.8 compared with 16.6 +/- 7.8 micromol glycosol units*g dry wt(-)(1)*h(-)(1), respectively; P < 0.05). CONCLUSIONS: Addition of a mixture of protein hydrolysate and amino acids to a carbohydrate-containing solution (at an intake of 0.8 g carbohydrate*kg(-)(1)*h(-)(1)) can stimulate glycogen synthesis. However, glycogen synthesis can also be accelerated by increasing carbohydrate intake (0.4 g*kg(-)(1)*h(-)(1)) when supplements are provided at 30-min intervals.

Sports Med. 2003;33(2):117-44.

Determinants of post-exercise glycogen synthesis during short-term recovery.

Jentjens R, Jeukendrup A.

Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UK.

The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen.The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to ~50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high (> or =1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins may be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.

Sports Med. 2003;33(2):117-44.

Determinants of post-exercise glycogen synthesis during short-term recovery.

Jentjens R, Jeukendrup A.

Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UK.

The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen.The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to ~50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high (> or =1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins may be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.

Recovery from a cycling time trial is enhanced with carbohydrate-protein supplementation vs. isoenergetic carbohydrate supplementation.

Berardi JM, Noreen EE, Lemon PW.

Precision Nutrition, Inc, Toronto, Ontario, Canada. jb@johnberardi.com.

BACKGROUND: In this study we assessed whether a liquid carbohydrate-protein (C+P) supplement (0.8 g/kg C; 0.4 g/kg P) ingested early during recovery from a cycling time trial could enhance a subsequent 60 min effort on the same day vs. an isoenergetic liquid carbohydrate (CHO) supplement (1.2 g/kg). METHODS: Two hours after a standardized breakfast, 15 trained male cyclists completed a time trial in which they cycled as far as they could in 60 min (AM(ex)) using a Computrainer indoor trainer. Following AM(ex), subjects ingested either C+P, or CHO at 10, 60 and 120 min, followed by a standardized meal at 4 h post exercise. At 6 h post AM(ex) subjects repeated the time trial (PM(ex)). RESULTS: There was a significant reduction in performance for both groups in PM(ex) versus AM(ex). However, performance and power decreases between PM(ex) and AM(ex) were significantly greater (p

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 LL, Tufekovic G, Zebis MK, Crameri RM, Verlaan G, Kjaer M, Suetta C, Magnusson P, Aagaard P.

Sports Medicine Research, Unit/Team Denmark Test Center, Bispebjerg Hospital, DK-2400 Copenhagen, Denmark. LL_andersen@hotmail.com

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.

Am J Physiol. 1992 Nov;263(5 Pt 1):E928-34.

Leucine as a regulator of whole body and skeletal muscle protein metabolism in humans.

Nair KS, Schwartz RG, Welle S.

Department of Medicine, University of Vermont College of Medicine, Burlington 05401.

Leucine has been proposed as an in vivo regulator of protein metabolism, although the evidence for this in humans remains inconclusive. To test this hypothesis, we infused either L-leucine (154 +/- 1 mumol.kg-1 x h-1) or saline intravenously in six healthy men in two separate studies. L-Leucine infusion increased plasma concentrations of leucine and alpha-ketoisocaproate from 112 +/- 6 and 38 +/- 3 mumol/l to 480 +/- 27 (P < 0.001) and 94 +/- 13 mumol/l (P < 0.001), respectively, without any significant change in circulating insulin or C peptide levels. Leucine infusion decreased plasma concentrations of several amino acids and decreased whole body valine flux and valine oxidation (using L-[1-13C]valine as a tracer) and phenylalanine flux (using [2H5]-phenylalanine as a tracer). According to arteriovenous differences across the leg, the net balance of phenylalanine, valine, and lysine shifted toward greater retention during leucine infusion, whereas alanine balance did not change. Valine release and phenylalanine release from the leg (estimated from the dilution of respective tracers) decreased, indicating inhibition of protein degradation by leucine infusion. We conclude that leucine decreases protein degradation in humans and that this decreased protein degradation during leucine infusion contributes to the decrease in plasma essential amino acids. This study suggests a potential role for leucine as a regulator of protein metabolism in humans.

J Nutr. 2006 Feb;136(2):533S-537S.

Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise.

Norton LE, Layman DK.

Division of Nutritional Sciences, Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

High-performance physical activity and postexercise recovery lead to significant changes in amino acid and protein metabolism in skeletal muscle. Central to these changes is an increase in the metabolism of the BCAA leucine. During exercise, muscle protein synthesis decreases together with a net increase in protein degradation and stimulation of BCAA oxidation. The decrease in protein synthesis is associated with inhibition of translation initiation factors 4E and 4G and ribosomal protein S6 under regulatory controls of intracellular insulin signaling and leucine concentrations. BCAA oxidation increases through activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH). BCKDH activity increases with exercise, reducing plasma and intracellular leucine concentrations. After exercise, recovery of muscle protein synthesis requires dietary protein or BCAA to increase tissue levels of leucine in order to release the inhibition of the initiation factor 4 complex through activation of the protein kinase mammalian target of rapamycin (mTOR). Leucine’s effect on mTOR is synergistic with insulin via the phosphoinositol 3-kinase signaling pathway. Together, insulin and leucine allow skeletal muscle to coordinate protein synthesis with physiological state and dietary intake

Med Sci Sports Exerc. 2006 Feb;38(2):268-75.

Effects of increasing insulin secretion on acute postexercise blood glucose disposal.

Kaastra B, Manders RJ, Van Breda E, Kies A, Jeukendrup AE, Keizer HA, Kuipers H, Van Loon LJ.

Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, Maastricht, The Netherlands.

Coingestion of protein and/or free amino acids with carbohydrate has been reported to accelerate postexercise muscle glycogen synthesis due to an increase in the insulin response.To determine the extent to which the combined ingestion of carbohydrate and a casein protein hydrolysate with or without additional free leucine can increase insulin levels during postexercise recovery in endurance-trained athletes. To determine how this affects whole-body plasma glucose disposal during postexercise recovery. Fourteen male athletes (age: 24.3 +/- 0.8 yr; VO2max: 62.9 +/- 1.4 mL.kg.min) were subjected to three randomized crossover trials in which they performed 2 h of exercise (55% Wmax). Thereafter, subjects were studied for 3.5 h during which they ingested carbohydrate (CHO: 0.8 g.kg.h), carbohydrate and a protein hydrolysate (CHO-PRO: 0.8 and 0.4 g.kg.h, respectively), or carbohydrate, a protein hydrolysate, and free leucine (CHO-PRO-LEU: 0.8, 0.4, and 0.1 g.kg.h, respectively) in a double-blind fashion. Continuous infusions with [6,6-H2] glucose were applied to quantify plasma glucose appearance (Ra) and disappearance rates (Rd). Plasma insulin responses were 108 +/- 17 and 190 +/- 33% greater in the CHO-PRO and CHO-PRO-LEU trial, respectively, compared with the CHO-trial (P < 0.01). Plasma glucose responses were lower in the CHO-PRO and CHO-PRO-LEU trial compared with the CHO-trial (35 +/- 5 and 42 +/- 11% lower, respectively; P < 0.01). Plasma glucose Ra and Rd were greater in the CHO versus the CHO-PRO and CHO-PRO-LEU trials (P < 0.05). Glucose Rd represented 100 +/- 0.03% of Ra in all trials.The combined ingestion of a protein hydrolysate and/or free leucine with carbohydrate (0.8 g.kg.h) substantially augments insulin secretion, but does not affect plasma glucose disposal during the first 3.5 h of postexercise recovery in trained athletes.

Eur J Appl Physiol. 2006 Aug;97(6):664-72. Epub 2005 Oct 29.

Effects of dietary leucine supplementation on exercise performance.

Crowe MJ, Weatherson JN, Bowden BF.

Institute of Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia.

Branched chain amino acids (BCAA), particularly leucine, have been suggested to be ergogenic for both endurance and strength/power performance. This study investigated the effects of dietary leucine supplementation on the exercise performance of outrigger canoeists. Thirteen (ten female, three male) competitive outrigger canoeists [aged 31.6 (2.2) year, VO(2max) 47.1 (2.0) ml kg(-1) min(-1)] underwent testing before and after 6-week supplementation with either capsulated L: -leucine (45 mg kg(-1) d(-1); n = 6) or placebo (cornflour; n = 7). Testing included anthropometry, 10 s upper body power and work and a row to exhaustion at 70-75% maximal aerobic power where perceived exertion (RPE), heart rate (HR) and plasma BCAA and tryptophan concentrations were assessed. Leucine supplementation resulted in significant increases in plasma leucine and total BCAA concentrations. Upper body power and work significantly increased in both groups after supplementation but power was significantly greater after leucine supplementation compared to the placebo [6.7 (0.7) v. 6.0 (0.7) W kg(-1)]. Rowing time significantly increased [77.6 (6.3)-88.3 (7.3) min] and average RPE significantly decreased [14.5 (1.5)-12.9 (1.4)] with leucine supplementation while these variables were unchanged with the placebo. Leucine supplementation had no effect on the plasma tryptophan to BCAA ratio, HR or anthropometric variables. Six weeks’ dietary leucine supplementation significantly improved endurance performance and upper body power in outrigger canoeists without significant change in the plasma ratio of tryptophan to BCAA.

Amino Acids. 2004 Mar;26(2):203-7. Epub 2003 May 9.

Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men.

Zhang M, Izumi I, Kagamimori S, Sokejima S, Yamagami T, Liu Z, Qi B.

Department of Welfare Promotion and Epidemiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.

To evaluate the protective effects of taurine supplementation on exercise-induced oxidative stress and exercise performance, eleven men aged 18-20 years were selected to participate in two identical bicycle ergometer exercises until exhaustion. Single cell gel assay (SCG assay) was used to study DNA damage in white blood cells (WBC). Pre-supplementation of taurine, a significant negative correlation was found between plasma taurine concentration before exercise and plasma thiobaribituric-acid reactive substance (TBARS) 6 hr after exercise (r = -0.642, p<0.05). WBC showed a significant increase in DNA strand breakage 6 hr and 24 hr after exercise. Seven-day taurine supplementation reduced serum TBARS before exercise ( p<0.05) and resulted in a significantly reduced DNA migration 24 hr after exercise ( p<0.01). Significant increases were also found in VO(2)max, exercise time to exhaustion and maximal workload in test with taurine supplementation ( p<0.05). After supplementation, the change in taurine concentration showed positive correlations with the changes in exercise time to exhaustion and maximal workload. The results suggest that taurine may attenuate exercise-induced DNA damage and enhance the capacity of exercise due to its cellular protective properties.

Amino Acids. 2002 Jun;22(4):309-24.

The cytoprotective role of taurine in exercise-induced muscle injury.

Dawson R Jr, Biasetti M, Messina S, Dominy J.

Department of Pharmacodynamics, College of Pharmacy, JHMHC Box 100487, University of Florida, Gainesville, FL 32610, U.S.A. dawson@cop.ufl.edu

Intense exercise is thought to increase oxidative stress and damage muscle tissue. Taurine is present in high concentration in skeletal muscle and may play a role in cellular defenses against free radical-mediated damage. The aim of this study was to determine if manipulating muscle levels of taurine would alter markers of free radical damage after exercise-induced injury. Adult male Sprague-Dawley rats were supplemented via the drinking water with either 3% (w/v) taurine (n = 10) or the competitive taurine transport inhibitor, beta-alanine (n = 10), for one month. Controls (n = 20) drank tap water containing 0.02% taurine and all rats were placed on a taurine free diet. All the rats except one group of sedentary controls (n = 10) were subjected to 90 minutes of downhill treadmill running. Markers of cellular injury and free radical damage were determined along with tissue amino acid content. The 3% taurine treatment raised plasma levels about 2-fold and 3% beta-alanine reduced plasma taurine levels about 50%. Taurine supplementation (TS) significantly increased plasma glutamate levels in exercised rats. Exercise reduced plasma methionine levels and taurine prevented its decline. Taurine supplementation increased muscle taurine content significantly in all muscles except the soleus. beta-alanine decreased muscle taurine content about 50% in all the muscles examined. Lipid peroxidation (TBARS) was significantly increased by exercise in the extensor digitorium longus (EDL) and gastrocnemius (GAST) muscles. Both taurine and beta-alanine completely blocked the increase in TBARs in the EDL, but had no effect in the GAST. Muscle content of the cytosolic enzyme, lactate dehydrogenase (LDH) was significantly decreased by exercise in the GAST muscle and this effect was attenuated by both taurine and beta-alanine. Muscle myeloperoxidase (MPO) activity was significantly elevated in the gastrocnemius muscle, but diet had no effect. MPO activity was significantly increased by exercise in the liver and both taurine and beta-alanine blocked this effect. There was no effect of either exercise or the diets on MPO activity in the lung or spleen. Running performance as assessed by a subjective rating scale was improved by taurine supplementation and there was a significant loss in body weight in the beta-alanine-treated rats 24 hours after exercise. In summary, taurine supplementation or taurine depletion had measurable cytoprotective actions to attenuate exercise-induced injury.

Int J Sports Med. 2009 Jul;30(7):485-8. Epub 2009 May 19.

Caffeine and taurine enhance endurance performance.

Imagawa TF, Hirano I, Utsuki K, Horie M, Naka A, Matsumoto K, Imagawa S.

Doctoral Program of Sports Medicine, University of Tsukuba, GSCHS, 1-1-1 D507, Tennoudai, Ibaraki, Tsukuba 305-8577, Japan. ima3sytag8sr@md.tsukuba.ac.jp

Caffeine enhances endurance performance; however, its effect on accumulated lactate remains unclear. Conversely, taurine, which also enhances endurance performance, decreases accumulated lactate. In this study, the effect of combination of caffeine and taurine on endurance performance was assessed. Mice ran on a treadmill, and the accumulated lactate was measured. In addition, muscle fibers from the gastrocnemius muscle of the mice were stained with ATPase and analyzed. The use of caffeine and taurine over a 2 week period enhanced endurance performance. Moreover, taurine significantly decreased the accumulated concentration of lactate over long running distances. However, the diameter of the cross-sections and ratios of Types I, IIA, and IIB muscle fibers were not affected.

J Sports Med Phys Fitness. 2008 Sep;48(3):347-51.

Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system.

Negro M, Giardina S, Marzani B, Marzatico F.

Pharmacobiochemistry Laboratory, Section of Pharmacology and Pharmacological Biotechnology, Department of Cellular and Molecular, Physiological and Pharmacological Sciences, University of Pavia, Pavia, Italy.

Since the 1980’s there has been high interest in branched-chain amino acids (BCAA) by sports nutrition scientists. The metabolism of BCAA is involved in some specific biochemical muscle processes and many studies have been carried out to understand whether sports performance can be enhanced by a BCAA supplementation. However, many of these researches have failed to confirm this hypothesis. Thus, in recent years investigators have changed their research target and focused on the effects of BCAA on the muscle protein matrix and the immune system. Data show that BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis. Muscle damage develops delayed onset muscle soreness: a syndrome that occurs 24-48 h after intensive physical activity that can inhibit athletic performance. Other recent works indicate that BCAA supplementation recovers peripheral blood mononuclear cell proliferation in response to mitogens after a long distance intense exercise, as well as plasma glutamine concentration. The BCAA also modifies the pattern of exercise-related cytokine production, leading to a diversion of the lymphocyte immune response towards a Th1 type. According to these findings, it is possible to consider the BCAA as a useful supplement for muscle recovery and immune regulation for sports events.

J Appl Physiol. 2004 Aug;97(2):585-91. Epub 2004 Apr 23.

Chronic glutamine supplementation increases nasal but not salivary IgA during 9 days of interval training.

Krieger JW, Crowe M, Blank SE.

Clinical and Experimental Exercise Science Graduate Program, Washington State University, Spokane, PO Box 1495, Spokane, WA 99210-1495, USA.

Oral glutamine supplementation during and after exercise abolishes exercise-induced decreases in plasma glutamine concentration but does not affect secretory IgA (sIgA) salivary output. Whether chronic glutamine supplementation during high-intensity interval training influences salivary and nasal sIgA concentration is unknown. The purpose of this study was examine the effects of chronic glutamine supplementation on sIgA during intense running training. Runners (n = 13, body mass 69.9 +/- 2.8 kg, peak whole body oxygen uptake 55.5 +/- 2 ml.kg(-1).min(-1), age 29.1 +/- 2.8 yr) participated in twice-daily interval training for 9-9.5 days, followed by recovery (5-7 days). Oral glutamine supplement (0.1 g/kg) or placebo was given four times daily for the first 14 days. After an overnight fast, venous blood, nasal washes, and stimulated saliva were collected at baseline (T1), midtraining (T2), posttraining (T3), and after recovery (T4). Mood states were assessed by using Profile of Mood States (POMS) inventories. We found that glutamine concentration in resting subjects decreased from T1 to T4 (P < 0.05) and was not altered by supplementation. Salivary IgA concentration and output were unchanged by training or supplementation. Mean nasal IgA across the study period was greater in runners receiving glutamine (264.7 +/- 35.0 microg/mg protein) vs. placebo (172.4 +/- 33.7 microg/mg protein; P < 0.05). POMS analyses indicated that vigor was lower at T3 vs. T1 (P < 0.05) and fatigue was higher at T2 vs. T1 and T4 (P < 0.05). We conclude that chronic glutamine supplementation during interval training results in higher nasal IgA than placebo but does not affect salivary IgA concentration or output.

Pol Merkur Lekarski. 2009 Jul;27(157):19-21.

The comparison of alpha-lipoic acid, melatonin, vitamin C and trolox effectiveness in decreasing DNA stand brakes and increasing plasma antioxidant power

Piechota A, Goraca A.

Uniwersytet Medyczny w odzi, Katedra Fizjologii Doswiadczalnej i Klinicznej, Zakiad Fizjologii Ukiadu Krazenia. piechota.aleksandra@wp.pl

Human plasma contains different antioxidants which may be important in the maintenance of an antioxidant status. The aim of this study was to compare the effect of exogenous antioxidants (vitamin C, trolox, alpha-lipoic acid and melatonin) on DNA standard brakes level and antioxidant activity of plasma. MATERIAL AND METHODS: Blood was obtain from 24 healthy volunteers from 19-23 of age and centrifuge. Vitamin C (vit C), trolox (water soluble vitamin E), lipoic acid (LA) or melatonin (MEL) were added separately to the plasma right before assay. Final concentration of each antioxidant in plasma was 1 mmol. Antioxidant properties of plasma and plasma with antioxidants were evaluated by three methods: level of DNA damages, ferric reducing ability of plasma (FRAP), scavenging of DPPH (2,2′-diphenyl-1-picrylhydrazyl) radical. RESULTS: We showed that vit C and trolox have strong ability to reduce bivalent iron (p<0.001 and p<0.001, respectively). The highest protective effect on hydroxyl radical-induced DNA damage was observed for trolox and LA (p<0.001 and p<0.01, respectively). All antioxidants possessed weak ability to scavenge DPPH radicals. CONCLUSION: In our study trolox and vitamin C effectively diminished DNA oxidative damages and possessed the highest antioxidant properties. Melatonin and lipoic acid decreased DNA damages but did not increase plasma antioxidant ability.

J Physiol Pharmacol. 2009 Jun;60(2):139-43.

Assessment of the antioxidant effectiveness of alpha-lipoic acid in healthy men exposed to muscle-damaging exercise.

Zembron-Lacny A, Slowinska-Lisowska M, Szygula Z, Witkowski K, Stefaniak T, Dziubek W.

Department of Biochemistry and Sports Medicine, University of Physical Education Poznan, Faculty of Physical Culture, Gorzow Wlkp., Poland. agzem@gorzow.home.pl

The aim of this study was to compare the indices of glutathione antioxidant system and oxidative damage level in resistance trained and untrained subjects and to assess the antioxidant action of alpha-lipoic acid in trained men exposed to muscle-damaging exercise. Thirteen trained and twenty untrained men (NT) participated in the comparative study. Then trained men were randomly assigned to T(CON) group (control) or T(ALA) group (alpha-lipoic acid, 600 mg . day(-1), for 8 days) and performed isometric/isokinetic effort of quadriceps muscles. The study has shown the significantly higher erythrocyte levels of glutathione (GSH), glutathione reductase (GR) and glutathione peroxidase (GPx) in T(CON) than NT but no differences in plasma lipid peroxidation (TBARS) and protein carbonylation (PC). However, total thiol (TT) concentration was two-fold lower in T(CON) than NT group. alpha-Lipoic acid variously influenced the post-exercise levels of GSH (+40%), GR (-24%) and GPx (+29%), but markedly reduced by over 30% the resting and post-exercise TBARS and PC in T(ALA) compared with T(CON). TT concentration significantly increased in T(ALA) but it did not reach the high level which was found in untrained group. It is concluded that alpha-lipoic acid supplementation diminishes oxidative damage. It does not abolish differences in glutathione antioxidant system between untrained and trained subjects but modulates a pro-antioxidant response to the muscle-damaging exercise.

J Appl Physiol. 1999 Apr;86(4):1191-6.

Alpha-lipoic acid supplementation: tissue glutathione homeostasis at rest and after exercise.

Khanna S, Atalay M, Laaksonen DE, Gul M, Roy S, Sen CK.

Department of Physiology, Faculty of Medicine, University of Kuopio, 70211 Kuopio, Finland.

Antioxidant nutrients have demonstrated potential in protecting against exercise-induced oxidative stress. alpha-Lipoic acid (LA) is a proglutathione dietary supplement that is known to strengthen the antioxidant network. We studied the effect of intragastric LA supplementation (150 mg/kg, 8 wk) on tissue LA levels, glutathione metabolism, and lipid peroxidation in rats at rest and after exhaustive treadmill exercise. LA supplementation increased the level of free LA in the red gastrocnemius muscle and increased total glutathione levels in the liver and blood. The exercise-induced decrease in heart glutathione S-transferase activity was prevented by LA supplementation. Exhaustive exercise significantly increased thiobarbituric acid-reactive substance levels in the liver and red gastrocnemius muscle. LA supplementation protected against oxidative lipid damage in the heart, liver, and red gastrocnemius muscle. This study reports that orally supplemented LA is able to favorably influence tissue antioxidant defenses and counteract lipid peroxidation at rest and in response to exercise.