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Ten weeks of branched-chain amino acid supplementation improves select performance and immunological variables in trained cyclists

March 2016
Amino Acids 12(Suppl 1)

DOI:10.1007/s00726-015-2125-8

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CC BY 4.0

Authors:

Wesley Kephart

Auburn University

Richard M Thompson

Auburn University

C. Brooks Mobley

Auburn University

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We examined if supplementing trained cyclists (32 ± 2 year, 77.8 ± 2.6 kg, and 7.4 ± 1.2 year training) with 12 g/day (6 g/day L-Leucine, 2 g/day L-Isoleucine and 4 g/day L-Valine) of either branched-chain amino acids (BCAAs, n = 9) or a maltodextrin placebo (PLA, n = 9) over a 10-week training season affected select body composition, performance, and/or immune variables. Before and after the 10-week study, the following was assessed: (1) 4-h fasting blood draws; (2) dual X-ray absorptiometry body composition; (3) Wingate peak power tests; and (4) 4 km time-trials. No group × time interactions existed for total lean mass (P = 0.27) or dual-leg lean mass (P = 0.96). A significant interaction existed for body mass-normalized relative peak power (19 % increase in the BCAA group pre- to post-study, P = 0.01), and relative mean power (4 % increase in the BCAA group pre- to post-study, P = 0.01). 4 km time-trial time to completion approached a significant interaction (P = 0.08), as the BCAA group improved in this measure by 11 % pre- to post-study, though this was not significant (P = 0.15). There was a tendency for the BCAA group to present a greater post-study serum BCAA: L-Tryptophan ratio compared to the PLA group (P = 0.08). A significant interaction for neutrophil number existed (P = 0.04), as there was a significant 18 % increase within the PLA group from the pre- to post-study time point (P = 0.01). Chronic BCAA supplementation improves sprint performance variables in endurance cyclists. Additionally, given that BCAA supplementation blunted the neutrophil response to intense cycling training, BCAAs may benefit immune function during a prolonged cycling season.

Pre- and post-study body composition variables. Pre-study (pre) and 10-week post-study (post) body composition variables. No group *time interactions were observed for body fat percentage (panel a), body fat mass (panel b), total lean body mass (LBM; panel c), or dual leg LBM (panel d)

…

Effects of chronic BCAA supplementation on Wingate variables in cyclists. Pre-study (pre) and 10-week post-study (post) Wingate variables. A group × time interaction was observed for peak power (P = 0.02), and the BCAA group increased peak power by 20 % compared to the pre-study time point (**P = 0.01) (panel a). A group × time interaction was also observed for relative peak power (P = 0.01), and the BCAA group increased relative peak power by 19 % compared to the pre-study time point (**P = 0.01) (panel b). A group × time interaction was observed for mean power (P = 0.01), and the BCAA group increased mean power by 4 % compared to the pre-study time point (**P = 0.01) (panel c). No group × time interactions was observed for relative mean power (MP; panel d)

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Effects of chronic BCAA supplementation on 4 km time-trial measures in cyclists. Pre-study (pre) and 10-week post-study (post) 4 km time-trial measures. No significant group × time interactions were observed for 4 km time-trial (TT) time to completion (panel a), 4 km TT power (panel b) or 4 km TT relative power (panel c)

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Effects of chronic BCAA supplementation on fasting serum amino acids in cyclists. Pre-study (pre) and 10-week post-study (post) fasting serum amino acid analyses. No significant group × time interactions were observed for serum BCAAs (panel a), serum l-Tryptophan (panel b) or the serum BCAA: l-Tryptophan ratio (panel c). There was a main time effect for serum l-Tryptophan to increase from the pre- to post-study time point when both group means were collapsed over time (‡P < 0.05). Likewise, there was a tendency for the serum BCAA: l-Tryptophan levels to decrease from the pre- to post-study time point when both group means were collapsed over time, and there was a tendency for this value to be greater in the BCAA group versus PLA group at the post-study time point (P = 0.08)

…

Effects of chronic BCAA supplementation on immune variables in cyclists. Pre-study (pre) and 10-week post-study (post) immune variables. No significant group × time interactions was observed for while blood cell counts (panel a). A group × time interaction trend was observed for neutrophil percentages (P = 0.06; panel b). A group × time interaction existed for neutrophil number (P = 0.04), and there was an 18 % increase within the PLA group from the pre- to post-study time points (**P = 0.01) (panel c). No significant group*time interactions were observed for lymphocyte percentages and counts (panels d, e) or monocyte percentages and counts (panels f, g). Other symbols: †between-group difference at a given time point (P < 0.05)

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POSTER PRESENTATION Open Access

Ten weeks of branched chain amino acid

supplementation improves select performance

and immunological variables in trained cyclists

Wesley C Kephart

, Taylor D Wachs

, R Mac Thompson

, C Brooks Mobley

, Carlton D Fox

, James R McDonald

Brian S Ferguson

, Kaelin C Young

, Ben Nie

, Jeffrey S Martin

1,2

, Joseph M Company

, David D Pascoe

1,2

Robert D Arnold

, Jordan R Moon

, Michael D Roberts

1,2*

From The Twelfth International Society of Sports Nutrition (ISSN) Conference and Expo

Austin, TX, USA. 11-13 June 2015

Background

We examined if supplementing trained cyclists (32 ± 2 yr,

77.8 ± 2.6 kg, and 7.4 ± 1.2 yr training) with 12g/d (6g/d

L-Leucine, 2g/d L-Isoleucine and 4g/d L-Valine) of either

branched chain amino acids (BCAAs, n = 9) or a malto-

dextrin placebo (PLA, n = 9) over a 10-week training sea-

son affected select body composition, performance,

and/or immune variables.

Methods

Before and after the 10-week study, the following was

assessed: a) 4-h fasting blood draws; b) dual X-ray

absorptiometry body composition; c) Wingate peak

power tests; and d) 4km time-trials.

Results

No group*time interactions existed for total lean mass

(p = 0.27) or dual-leg lean mass (p = 0.96). A significant

interaction existed for body mass-normalized relative

peak power (19% increase in the BCAA group pre- to

post-study, p = 0.01), and relative mean power

(4% increase in the BCAA group pre- to post-study, p =

0.01). 4km time-trial time to completion approached a

significant interaction (p = 0.08), as the BCAA group

improved in this measure by 11% pre- to post-study,

though this was not significant (p = 0.15). There was a

tendency for the BCAA group to present a greater post-

study serum BCAA: L-Tryptophan ratio compared to

the PLA group (p = 0.08). A significant interaction for

neutrophil number existed (p = 0.04), as there was a

significant 18% increase within the PLA group from

the pre- to post-study time point (p = 0.01).

Conclusions

Chronic BCAA supplementation improves sprint perfor-

mance variables in endurance cyclists. Additionally, given

that BCAA supplementation blunted the neutrophil

response to intense cycling training, BCAAs may benefit

immune function during a prolonged cycling season.

Authors’details

School of Kinesiology, Auburn University, Auburn, AL, USA.

Edward Via

College of Osteopathic Medicine, Auburn Campus, Auburn, AL, USA.

Harrison School of Pharmacy, Auburn University, Auburn, AL, USA.

Endurance Company, LLC, Bloomington, IL, USA.

MusclePharm Sports

Science Institute, Denver, CO, USA.

Published: 21 September 2015

doi:10.1186/1550-2783-12-S1-P20

Cite this article as: Kephart et al.: Ten weeks of branched chain amino

acid supplementation improves select performance and immunological

variables in trained cyclists. Journal of the International Society of Sports

Nutrition 2015 12(Suppl 1):P20.

* Correspondence: mdr0024@auburn.edu

School of Kinesiology, Auburn University, Auburn, AL, USA

Full list of author information is available at the end of the article

Kephart et al.Journal of the International Society of Sports Nutrition 2015, 12(Suppl 1):P20

http://www.jissn.com/content/12/S1/P20

creativecommons.org/licenses/by/4.0), which permits unr estricted use, distribution, and reproduction in any medium, provided the

original work is properly cited. The Cre ative Commons Public Do main Dedication waiver (http://creativecommons.org/publicdomain/

zero/1.0/) applies to the data made availa ble in this article, unless otherwise stated.

Access to this full-text is provided by Springer Nature.

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Common questions and misconceptions about protein supplementation: what does the scientific evidence really show?

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Protein supplementation often refers to increasing the intake of this particular macronutrient through dietary supplements in the form of powders, ready-to-drink shakes, and bars. The primary purpose of protein supplementation is to augment dietary protein intake, aiding individuals in meeting their protein requirements, especially when it may be challenging to do so through regular food (i.e. chicken, beef, fish, pork, etc.) sources alone. A large body of evidence shows that protein has an important role in exercising and sedentary individuals. A PubMed search of "protein and exercise performance" reveals thousands of publications. Despite the considerable volume of evidence, it is somewhat surprising that several persistent questions and misconceptions about protein exist. The following are addressed: 1) Is protein harmful to your kidneys? 2) Does consuming "excess" protein increase fat mass? 3) Can dietary protein have a harmful effect on bone health? 4) Can vegans and vegetarians consume enough protein to support training adaptations? 5) Is cheese or peanut butter a good protein source? 6) Does consuming meat (i.e., animal protein) cause unfavorable health outcomes? 7) Do you need protein if you are not physically active? 8) Do you need to consume protein ≤ 1 hour following resistance training sessions to create an anabolic environment in skeletal muscle? 9) Do endurance athletes need additional protein? 10) Does one need protein supplements to meet the daily requirements of exercise-trained individuals? 11) Is there a limit to how much protein one can consume in a single meal? To address these questions, we have conducted a thorough scientific assessment of the literature concerning protein supplementation.

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Aug 2023

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The Effect of Acute Pre-Workout Supplement Ingestion on Basketball-Specific Performance of Well-Trained Athletes

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Effects of branched chain amino acids, l-citrulline, and alpha-glycerylphosphorylcholine supplementation on exercise performance in trained cyclists: a randomized crossover trial

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May 2023
Sports Nutr Rev J

Renee Harrington

Background: Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance. Methods: In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period. Results: There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test. Conclusions: The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.

Molecular predictors of resistance training outcomes in young untrained female adults

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We sought to determine if the myofibrillar protein synthetic (MyoPS) response to a naïve resistance exercise (RE) bout, or chronic changes in satellite cell number and muscle ribosome content, were associated with hypertrophic outcomes in females or differed in those who classified as higher (HR) or lower (LR) responders to resistance training (RT). Thirty-four untrained college-aged females (23.4±3.4 kg/m2) completed a 10-week RT protocol (twice weekly). Body composition and leg imaging assessments, a right leg vastus lateralis biopsy, and strength testing occurred before and following the intervention. A composite score, which included changes in whole-body lean tissue mass (LSTM), vastus lateralis (VL) muscle cross-sectional area (mCSA), mid-thigh mCSA, and deadlift strength, was used to delineate upper and lower HR (n=8) and LR (n=8) quartiles. In all participants, training significantly (p<0.05) increased LSTM, VL mCSA, mid-thigh mCSA, deadlift strength, mean muscle fiber cross-sectional area, satellite cell abundance, and myonuclear number. Increases in LSTM (p<0.001), VL mCSA (p<0.001), mid-thigh mCSA (p<0.001), and deadlift strength (p=0.001) were greater in HR versus LR. The first-bout 24-hour MyoPS response was similar between HR and LR (p=0.367). While a no significant responder*time interaction existed for muscle total RNA concentrations (i.e., ribosome content) (p=0.888), satellite cell abundance increased in HR (p=0.026) but not LR (p=0.628). Pre-training LSTM (p=0.010) VL mCSA (p=0.028), and mid-thigh mCSA (p<0.001) were also greater in HR versus LR. Female participants with an enhanced satellite cell response to RT, and more muscle mass prior to RT, exhibited favorable resistance training adaptations.

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May 2012
Sports Nutr Rev J

Background It is well documented that exercise-induced muscle damage (EIMD) decreases muscle function and causes soreness and discomfort. Branched-chain amino acid (BCAA) supplementation has been shown to increase protein synthesis and decrease muscle protein breakdown, however, the effects of BCAAs on recovery from damaging resistance training are unclear. Therefore, the aim of this study was to examine the effects of a BCAA supplementation on markers of muscle damage elicited via a sport specific bout of damaging exercise in trained volunteers. Methods Twelve males (mean ± SD age, 23 ± 2 y; stature, 178.3 ± 3.6 cm and body mass, 79.6 ± 8.4 kg) were randomly assigned to a supplement (n = 6) or placebo (n = 6) group. The damaging exercise consisted of 100 consecutive drop-jumps. Creatine kinase (CK), maximal voluntary contraction (MVC), muscle soreness (DOMS), vertical jump (VJ), thigh circumference (TC) and calf circumference (CC) were measured as markers of muscle damage. All variables were measured immediately before the damaging exercise and at 24, 48, 72 and 96 h post-exercise. Results A significant time effect was seen for all variables. There were significant group effects showing a reduction in CK efflux and muscle soreness in the BCAA group compared to the placebo (P<0.05). Furthermore, the recovery of MVC was greater in the BCAA group (P<0.05). The VJ, TC and CC were not different between groups. Conclusion The present study has shown that BCAA administered before and following damaging resistance exercise reduces indices of muscle damage and accelerates recovery in resistance-trained males. It seems likely that BCAA provided greater bioavailablity of substrate to improve protein synthesis and thereby the extent of secondary muscle damage associated with strenuous resistance exercise. Clinical Trial Registration Number: NCT01529281.

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This study was designed to compare the effects of energy-matched carbohydrate (CHO) and carbohydrate-protein (CHO-PRO) supplements on cycling time-trial performance. Twelve competitive male cyclists and triathletes each completed 2 trials in a randomized and counterbalanced order that were separated by 5-10 d and applied in a double-blind manner. Participants performed a 45-min variable-intensity exercise protocol on a cycle ergometer while ingesting either a 9% CHO solution or a mixture of 6.8% CHO plus 2.2% protein in volumes providing 22 kJ/kg body mass. Participants were then asked to cycle 6 km in the shortest time possible. Blood glucose and lactate concentrations were measured every 15 min during exercise, along with measures of substrate oxidation via indirect calorimetry, heart rate, and ratings of perceived exertion. Mean time to complete the 6-km time trial was 433 + or - 21 s in CHO trials and 438 + or - 22 s in CHO-PRO trials, which represents a 0.94% (CI: 0.01, 1.86) decrement in performance with the inclusion of protein (p = .048). However, no other variable measured in this study was significantly different between trials. Reducing the quantity of CHO included in a supplement and replacing it with protein may not represent an effective nutritional strategy when the supplement is ingested during exercise. This may reflect the central ergogenic influence of exogenous CHO during such activity.

Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise

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Jan 1995
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In this study, five men exercised the knee extensor muscles of one leg for 60 min (71 +/- 2% maximal work capacity) with and without (control) an oral supplement (77 mg/kg) of branched-chain amino acids (BCAA). BCAA supplementation resulted in a doubling (P < 0.05) of the arterial BCAA levels before exercise (339 +/- 15 vs. 822 +/- 86 microM). During the 60 min of exercise, the total release of BCAA was 68 +/- 93 vs. 816 +/- 198 mumol/kg (P < 0.05) for the BCAA and control trials, respectively. The intramuscular BCAA concentrations were higher (P < 0.05) for the BCAA trial and remained higher (P < 0.05) throughout exercise. In both trials, substantial quantities of NH3 were released, and when NH3 production equivalent to IMP accumulation was subtracted the net NH3 production was 1,112 +/- 279 and 1,670 +/- 245 mumol/kg (P < 0.05) for the control and BCAA trials, respectively. In contrast, the release of the essential amino acids (EAA) was much lower for the BCAA than the control trial (P < 0.05). When the BCAA were subtracted from the EAA (EAA-BCAA), the total release of EAA minus BCAA was lower (P < 0.05) for the BCAA (531 +/- 70 mumol/kg) than the control (924 +/- 148 mumol/kg) trial. These data suggest that BCAA supplementation results in significantly greater muscle NH3 production during exercise. Furthermore, the increased intramuscular and arterial BCAA levels before and during exercise result in a suppression of endogenous muscle protein breakdown during exercise.

Effects of carbohydrate feeding on plasma free tryptophan and branched-chain amino acids during prolonged cycling

Article

Nov 1992
Eur J Appl Physiol Occup Physiol

Brain serotonin (5-hydroxytryptamine, 5-HT) has been suggested to be involved in central fatigue during prolonged exercise. Changes in the ratio of plasma free tryptophan (free Trp) to branched-chain amino acids (BCAA) are associated with altered brain 5-HT synthesis. The purposes of this study were to describe systematically the effects of prolonged exercise on changes in plasma free Trp and BCAA and to examine the effects of carbohydrate (CHO) feedings on these same variables. Eight well-trained men [

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max = 57.8 (SE 4.1) ml kg−1 min−1] cycled for up to 255 min at a power output corresponding toVO2 at lactate threshold (approximately 68%VO2max) on three occasions separated by at least 1 week. Subjects drank 5 ml kg−1 body wt−1 of either a water placebo, or a liquid beverage containing a moderate (6% CHO) or high (12% CHO) concentration of carbohydrate beginning at min 14 of exercise and every 30 min thereafter. Exercise time to fatigue was shorter in subjects receiving placebo [190 (SE 4) min] as compared to 6% CHO [235 (SE 10) min] and 12% CHO [234 (SE 9) min] (P<0.05). Glucose and insulin decreased in the placebo group, and free Trp, free-Trp/BCAA, and free fatty acids increased approximately five- to sevenfold (P < 0.05). These changes were attenuated in a dose-related manner by the carbohydrate drinks. Plasma free Trp and plasma free fatty acids were highly correlated (r=0.86,P<0.001). Plasma BCAA did not change in the placebo group, but decreased slightly in those receiving 6% CHO and 12% CHO (P<0.05). No differences in heart rate,

\dot V{\text{O}}_{\text{2}}

, plasma volume and respiratory exchange ratio were found. The results indicate that free Trp and free Trp/BCAA increase progressively during prolonged cycling to fatigue. This response was attenuated by CHO feedings. Changes in plasma free fatty acids probably play a prominent role in these responses.

Physical and mental fatigue: do changes in plasma amino acids play a role?

Article

May 1991

Mechanisms of activation of muscle branched-chain ??-keto acid dehydrogenase during exercise in man

Article

Sep 1996

1. Exercise leads to activation (dephosphorylation) of the branched-chain alpha-keto acid dehydrogenase (BCKADH). Here we investigate the effect of low pre-exercise muscle glycogen content and of branched-chain amino acid (BCAA) ingestion on the activity of BCKADH at rest and after 90 min of one-leg knee-extensor exercise at 65% maximal one-leg power output in five subjects. 2. Pre-exercise BCAA ingestion (308 mg BCAAs (kg body wt)-1) caused an increased muscle BCAA uptake, a higher intramuscular BCAA concentration and activation of BCKADH both at rest (9 +/- 1 versus 25 +/- 5% for the control and BCAA test, respectively) and after exercise (27 +/- 4 versus 54 +/- 7%). 3. At rest the percentage active BCKADH was not different, 6 +/- 2% versus 5 +/- 1%, in the normal and low glycogen content leg (392 +/- 21 and 147 +/- 34 mumol glycosyl units (g dry muscle)-1, respectively). The post-exercise BCKADH activity was higher in the low (46 +/- 2%) than in the normal glycogen content leg (26 +/- 2%). 4. It is concluded that: (1) the mechanism of activation by BCAA ingestion probably involves an increase of the muscle BCAA concentration; (2) BCKADH activation caused by exercise and BCAA ingestion are additive; (3) low pre-exercise muscle glycogen content augments the exercise-induced BCKADH activation without an increase in muscle BCAA concentration; and (4) the mechanism of BCKADH activation via BCAA ingestion and low muscle glycogen content are different.

Capacity of circulating neutrophils to produce reactive oxygen species after exhaustive exercise

Article

Oct 1996

To investigate the cause of disagreement within the large body of literature concerning the effect of exercise on the capacity of circulating neutrophils to produce reactive oxygen species (ROS), 10 male endurance-trained athletes underwent maximal exercise. The generation of superoxide radical (O2-.) by neutrophils was first detected on a cell-by-cell basis by using histochemical nitro blue tetrazolium tests performed directly on fresh unseparated blood, which showed that responsive neutrophils under several stimulatory conditions relatively decreased after exercise. Similarly, O2-. detected with bis-N-methylacridinium nitrate (lucigenin)-dependent chemiluminescence (CL) of a fixed number of purified neutrophils on stimulation with opsonized zymosan was decreased slightly after exercise. In contrast, the 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)-dependent CL response of the neutrophils indicative of the myeloperoxidase (MPO)-mediated formation of highly reactive oxidants was significantly enhanced after exercise. It therefore suggests that the pathway of neutrophil ROS metabolism might be forwarded from the precursor O2-. production to the stages of more reactive oxidant formation due to the facilitation of MPO degranulation. In addition, these phenomena were closely associated with the exercise-induced mobilization of neutrophils from the marginated pool into the circulation, which was mediated by the overshooting of catecholamines during exercise. These findings indicate that the use of different techniques for detecting ROS or the different stages of neutrophil ROS metabolism could explain some of the disparate findings of the previous studies.

Effects of glucose, glucose plus branched-chain amino acids, or placebo on bike performance over 100 km

Article

Jan 1997

This study was undertaken to determine the effects of ingesting either glucose (trial G) or glucose plus branched-chain amino acids (BCAA: trial B), compared with placebo (trial P), during prolonged exercise. Nine well-trained cyclists with a maximal oxygen uptake of 63.1 +/- 1.5 ml O2. min-1.kg-1 performed three laboratory trials consisting of 100 km of cycling separated by 7 days between each trial. During these trials, the subjects were encouraged to complete the 100 km as fast as possible on their own bicycles connected to a magnetic brake. No differences in performance times were observed between the three trials (160.1 +/- 4.1, 157.2 +/- 4.5, and 159.8 +/- 3.7 min, respectively). In trial B, plasma BCAA levels increased from 339 +/- 28 microM at rest to 1,026 +/- 62 microM after exercise (P < 0.01). Plasma ammonia concentrations increased during the entire exercise period for all three trials and were significantly higher in trial B compared with trials G and P (P < 0.05). The respiratory exchange ratio was similar in the three trials during the first 90 min of exercise; thereafter, it tended to drop more in trial P than in trials G and B. These data suggest that neither glucose nor glucose plus BCAA ingestion during 100 km of cycling enhance performance in well-trained cyclists.

Exercise-Induced Immunomodulation - Possible Roles of Neuroendocrine and Metabolic Factors

Article

Apr 1997

Acute muscular exercise induces an increased neutrophil count concomitant with recruitment of natural killer (NK), B and T cells to the blood as reflected by an elevation in the total lymphocyte count. Meanwhile, following intense exercise of long duration the lymphocyte count declines, non-MHC-restricted cytotoxicity is suppressed, but the neutrophil concentration increases. In relation to eccentric exercise involving muscle damage, the plasma concentrations of interleukin-1, interleukin-6 and the tumor necrosis factor are elevated. In this review we will propose a model based on the possible roles that stress hormones play a mediating the exercise- related immunological changes: adrenaline and to a lesser degree noradrenaline are responsible for the immediate effects of exercise on lymphocyte subpopulations and cytotoxic activities. The increase in catecholamines and growth hormone mediate the acute effects of exercise on neutrophils, whereas cortisol may be responsible for maintaining lymphopenia and neutrocytosis after exercise of long duration. Lastly, the role of beta-endorphin is less clear, but the cytokine response is closely related to muscle damage and stress hormones do not seem to be directly involved in the elevated cytokine level. Other possible mechanisms of exercise-induced immunomodulation may include the so-called glutamine hypothesis, which is based on the fact that skeletal muscle is an important source of glutamine production and that lymphocytes are dependent on glutamine for optimal growth. Furthermore, physiological changes during exercise, e.g. increased body temperature and decreased oxygen saturation may also in theory contribute to the exercise-induced immunological changes.

Pre-exercise branched-chain amino acid administration increases endurance performance in rats

Article

Sep 1997

This study investigated the effects of pre-exercise branched-chain amino acid (BCAA) administration on blood ammonia levels and on time to exhaustion during treadmill exercise in rats. Adult female Wistar rats were trained on a motor driven treadmill. After a 24-h fast, rats were injected intraperitoneally (i.p.) with 1 mL of placebo or BCAA (30 mg), 5 min before performing 30 min of submaximal exercise (N = 18) or running to exhaustion (N = 12). In both cases, rats were sacrificed immediately following exercise, and blood was collected for the measurement of glucose, nonesterified fatty acid (NEFA), lactic acid, BCAA, ammonia, and free-tryptophan (free-TRP) levels. Control values were obtained from sedentary rats that were subjected to identical treatments and procedures (N = 30). Plasma BCAA levels increased threefold within 5 min after BCAA administration. Mean run time to exhaustion was significantly longer (P < 0.01) after BCAA administration (99 +/- 9 min) compared with placebo (76 +/- 4 min). During exercise, blood ammonia levels were significantly higher (P < 0.01) in the BCAA treated compared with those in the placebo treated rats both in the 30-min exercise bout (113 +/- 25 mumol.L-1 (BCAA) vs 89 +/- 16 mumol.L-1) and following exercise to exhaustion (186 +/- 44 mumol.L-1 (BCAA) vs 123 +/- 19 mumol.L-1). These data demonstrate that BCAA administration in rats results in enhanced endurance performance and an increase in blood ammonia during exercise.

Ten weeks of branched-chain amino acid supplementation improves select performance and immunological variables in trained cyclists

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