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Effect of branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis



Abstract. Delayed onset muscle soreness (DOMS) is a symptom of exercise-induced muscle damage that occurs following exercise. Previous research has indicated that branched-chain amino acid (BCAA) supplementation may attenuate exercise-induced muscle damage that causes delayed onset muscle soreness, however the results are inconsistent. The primary aim of this study was to examine the previous literature assessing the effect of BCAA supplementation on DOMS following an acute bout of exercise in adults. This review was conducted in accordance with PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses), and identified peer-reviewed articles comparing a BCAA supplement to a placebo non-BCAA supplement following an acute bout of exercise. An electronic search of three databases (EbscoHost, Web of Science, and SPORTDiscus) yielded 42 articles after duplicates were removed. All studies included in the current analyis were: 1) peer-reviewed publications; 2) available in English; 3) utilized a random control design that compared a BCAA group to a placebo control group following exercise; 4) and assessed soreness of muscle tissue during recovery. DOMS was assessed in 61 participants following ingestion of a BCAA supplement over the course of these interventions. The cumulative results of 37 effects gathered from 8 studies published between 2007 and 2017 indicated that BCAA supplementation reduced DOMS following exercise training (ES = 0.7286, 95% CI: 0.5017 to 0.9555, p < 0.001). A large decrease in DOMS occurs following BCAA supplementation after exercise compared to a placebo supplement.
Branched-chain amino acids and muscle soreness
Michael V. Fedewa Ph.D.,1 Steven O. Spencer, M.A.,1 Tyler D. Williams Ph.D.,1,2 Zachery E.
Becker, M.A.,1 Collin A. Fuqua.1
Institutional Affiliations:
1Department of Kinesiology, The University of Alabama, Tuscaloosa, Alabama, United States.
2Department of Kinesiology, Samford University, Birmingham, Alabama, United States.
Address correspondence to: Michael V. Fedewa, The University of Alabama, Department of
Kinesiology, 2003 Moore Hall, Box 870312, Tuscaloosa, AL 35487-0231. Telephone: 205-348-
9779. Fax 205-348-0867. E-mail:
Key Words: delayed onset muscle soreness, branched-chain amino acid, exercise training, meta-
analysis, systematic review
Total word count (text only): 2,666
Number of pages: 15
Tables: 2
Figures: 3
Running Title: BCAA supplementation and muscle soreness
Competing Interest: The authors have no potential, perceived, or real conflicts of interest to
disclose. None of the authors declare competing financial interests.
Michael V. Fedewa (
Steven O. Spencer (
Tyler D. Williams (
Zachery E. Becker (
Collin A. Fuqua (
Branched-chain amino acids and muscle soreness
Delayed onset muscle soreness (DOMS) is a symptom of exercise-induced muscle
damage that occurs following exercise. Previous research has indicated that branched-chain
amino acid (BCAA) supplementation may attenuate exercise-induced muscle damage that causes
delayed onset muscle soreness, however the results are inconsistent. The primary aim of this
study was to examine the previous literature assessing the effect of BCAA supplementation on
DOMS after exercise, and to provide a quantitative estimate of effect on recovery status. This
review was conducted in accordance with PRISMA guidelines (Preferred Reporting Items for
Systematic Reviews and Meta-analyses), and identified peer-reviewed articles comparing a
BCAA supplement to a placebo non-BCAA supplement following an acute bout of exercise. An
electronic search of three databases (EbscoHost, Web of Science, and SPORTDiscus) yielded 39
articles after duplicates were removed. All studies included in the current analysis were: 1) peer-
reviewed publications; 2) available in English; 3) utilized a random control design that compared
a BCAA group to a placebo control group following exercise; 4) and assessed soreness of muscle
tissue during recovery. Data from 93 participants (22.3±2.7 yrs, 87% male, 18.6±2.3 per study)
were included in the analysis. The cumulative results of 26 effects gathered from 5 studies
published between 2007 and 2013 indicated that DOMS decreased following BCAA
supplementation (ES=0.8956, 95% CI: 0.6822 to 1.1090, p<0.001). A large decrease in DOMS
occurs following BCAA supplementation after exercise compared to a placebo supplement.
Branched-chain amino acids and muscle soreness
Delayed onset muscle soreness (DOMS) is a type of subclinical muscular injury which
occurs following exercise and can present symptoms that vary from slight tenderness and
stiffness to severe debilitating pain which restricts movement.[1] Typically, symptoms of DOMS
peak 24-48 hours after exercise, and subside within 7 days.[2] Although a number of possible
treatments are available, cryotherapy, stretching, anti-inflammatory drugs, electrical stimulation,
and dietary supplements are most commonly used to alleviate the increased muscle soreness
following exercise.[3] Specifically, branched-chain amino acid (BCAA) supplementation is used
to reduce DOMS, promote protein metabolism, and inhibit muscle damage following exercise
training, resulting in an anabolic effect on the muscles.[4] Although these amino acid
supplements appear to be safe when consumed in recommended dosages, current research does
not support an ergogenic effect of BCAA supplementation when consumed before or during
exercise.[5] BCAA supplementation has the potential to aid in the recovery of both athletes and
individuals who adhere to a strict workout regimen. DOMS that is associated with the events
these individuals engage in can severely restrict progress in their respective activities. BCAA
supplementation may be able to aid in the post-activity soreness and recovery, thus aiding in the
reduction of downtime between activities and training sessions.[6] This would allow for quicker
recovery and participation, thus allowing the individual to progress in their respective interests.
Additional research has emerged related to the potential benefits of BCAA supplementation
following exercise training to enhance recovery, however the effect of BCAA supplementation
on DOMS has yet to be completely characterized.[7] Should BCAA supplementation reduce
symptoms of DOMS, it is possible that exercise adherence may increase among sedentary
populations, and improve performance among athletes and non-athletes alike. As such, the
Branched-chain amino acids and muscle soreness
primary aim of this analysis is to examine the effect of BCAA supplementation on DOMS
following an acute bout of exercise in adults.
This study was conducted in accordance with PRISMA (Preferred Reporting Items for
Systematic Reviews and Meta-analyses) statement guidelines.[8] Articles published by February
20, 2016, were located by searching three electronic online databases, EBSCOhost,
SPORTDiscus, and Web of Science, using combinations of the terms branched-chain amino
acids, BCAA, delayed onset muscle soreness, DOMS, muscle, recovery, soreness, randomized
trial, and randomized controlled trial. Duplicate publications were removed, and the reference
lists from retrieved articles were manually reviewed for additional publications not discovered
during the database search.
Study Selection
The inclusion criteria for this analysis were as follows: (1) peer-reviewed publication; (2)
available in English; (3) involving human subjects; (4) randomized crossover and randomized
controlled trials including a BCAA and placebo supplement; (5) assessed muscle soreness
following a single bout of exercise training. Excluded studies had the following characteristics:
(1) were non-peer reviewed; (2) provided a review, meta-analysis, position statement, or
proposed study design; (3) used a cross-sectional or prospective study design; (4) included
BCAA intake as part of a multicomponent treatment (eg, BCAA + caffeine, BCAA +
preworkout), from which an ES for BCAA supplementation alone could not be calculated; or (5)
compared BCAA supplementation only with an active treatment (eg, nutritional intervention or
alternative supplementation). A total of 18 articles were identified during the initial search
process. A flowchart of the study selection method is provided in Fig 1. No additional
Branched-chain amino acids and muscle soreness
publications were identified by manually searching references of relevant publications. Study
characteristics (age, percent of the study sample comprised of female participants, total mass,
height, BMI, and relative adiposity (%Fat)) were extracted by two independent reviewers
(Authors 1 and 2). Discrepancies were resolved by consensus, with a third reviewer (Author 3)
available, if needed. Study methodological quality was assessed using the Jadad scale (Table 1).
[9] Randomization methods, blinding, and description of withdrawals were evaluated by
reviewers, and scored out of 5 total points. Higher scores indicate a greater number of key
criteria having been reported, and trials with scores ≥3 were considered of high methodological
Effect Size Calculation
ES values were calculated by subtracting the mean (M) change in the placebo condition
from the mean change in the BCAA condition and dividing the difference by the pooled standard
deviation (SD) of the baseline scores, and adjusted for small sample bias.[10] An improvement in
perceived pain/discomfort resulted in a positive ES. All authors independently calculated ES
from each study, with inconsistencies resolved prior to analyses.
Statistical Analysis
Random effects models were used to calculate a mean ES and 95% confidence interval
(CI) for the effect of BCAA supplementation on DOMS using macros (MeanES) in IBM SPSS
version 23.0 (IBM SPSS Statistics, IBM Corporation, Armonk, NY). Missing values not
obtained from the literature were imputed using the mean of the available values.[11] Multi-level
linear regression with maximum likelihood estimation was used according to standard
procedures to adjust for between-study variance and the correlation between effects nested
within studies.[12, 13] The data analysis for the multilevel model was performed using SAS 9.4
Branched-chain amino acids and muscle soreness
(SAS Institute Inc., Cary, North Carolina). Data available for study and participant characteristics
are presented as M±SD. Data available for study and subject characteristics are demonstrated as
DOMS was assessed in 93 participants over the course of these interventions. Study
samples ranged from 9 to 36 (27.4±9.4) participants per treatment effect, with 2 to 8 (5.2±2.7)
effects gathered from each study. A single bout of resistance training was the most commonly
used stimulus, occurring in 20 of the 26 effects (76.9%), with plyometrics (k=4, 15.4%), and
aerobic exercise (k=2, 7.7%). Characteristics of experimental designs are outlined in Table 1.
The cumulative results of 26 effects gathered from 5 studies published between 2007 and
2013 indicated that BCAA supplementation reduced DOMS following exercise training
(ES=0.8956, 95% CI: 0.6822 to 1.1090, p<0.001). The mean ES remained significant after
accounting for the nesting of multiple effects nested within a single study (ES=0.9490, 95%CI
0.4793 to 1.4187, p=0.0050). Although the effect of BCAA supplementation on DOMS did not
vary significantly from day to day, the magnitude of the effect appeared largest 48 hours
following exercise (Table 2). BCAA supplementation reduced DOMS consistently across 100%
of the effects analyzed in the current study.
Participant age ranged from 21.6 to 23.0 yrs (22.5±0.3 yrs). Only a small portion of
effects (k=4, 15.4%) of treatment effects consisted of trained individuals, whom would likely see
a minimal effect from BCAA supplementation. In contrast, 22 effects (84.6%) from untrained or
previously inactive participants whom would likely experience an exponentially greater benefit
from treatment. Despite discrepancies in training status, all participants were healthy with no
history of any medical conditions that could impede in performance or unintentionally influence
Branched-chain amino acids and muscle soreness
results. All 26 effects were obtained from sex-specific samples (k=22, 84.6% male only, k=4,
15.4% female only). Average BMI and %Fat across all effects were 22.4±1.3 kg/m2 and 18.2±1.8
%Fat, respectively.
Homogeneity of Results
Heterogeneity was indicated if Q total reached a significance level of P<.05 and the
sampling error accounted for >75% of the observed variance.[10] Heterogeneity was also
assessed by examination of the I2 statistic.[14] An I2 value was categorized as low, moderate, or
high based on calculations equal to 25%, 50%, or 75%, respectively. The effect of BCAA
supplementation on exercise-induced DOMS demonstrated low heterogeneity (Q=33.18,
I2=24.66, p=0.1266). Sampling error accounted for 95.6% of the variation observed in the
effects. Due to the low heterogeneity, the variability among ES was not different than what
would have occurred naturally as a result of study sample error. As a result, no further moderator
analysis was performed.
Assessment of Bias
Sixteen effects (61.5%) were obtained from high-quality studies, with overall quality of
scores for effects in the current analysis ranging from one to three (1.8±1.5). Sixteen effects
(61.5%) were randomized, however none of the effects were gathered from studies that provided
a description of the randomization process used (i.e. computer generated group allocation). A
placebo supplement was used in all of the effects included in the current analysis to blind
participants to the supplement being administered, however double-blinding procedures were
described in only 16 of the 26 effects (61.5%). None of the included studies described screening
procedures, enrollment of participants, or how the research team reached the final sample of
participants with complete data. Furthermore, these studies should have also included a
Branched-chain amino acids and muscle soreness
description of participants whom did not complete the observation period or who were not
included in the analysis, and reasons for their exclusion. The study quality assessment is also
presented as part of Table 1.
The number of unpublished or unretrieved null effects that would diminish the
significance of observed effects to a non-significant result was estimated as the fail-safe N. A
fail-safe N+ represents the minimal number of additional null effects from multiple studies of
average sample size needed to reach a similar null conclusion.[15] The fail-safe N+ for the effect
of BCAA supplementation on DOMS using a random effects model estimated N+=551.7 effects.
A fail-safe N+ is often considered robust when the estimated value exceeds 5N+10, in which N
represents the number of original effects. Given the current fail-safe N+, publication bias can be
“safely ignored.”[16] A funnel plot for the effect of BCAA supplementation on DOMS was
created as an exploratory assessment to address potential publication bias related to study sample
size, and is presented in Figure 3. Potential publication bias was also addressed using Egger’s
test.[17] Inconsistent with the fail-safe N+ estimate, the results from Egger’s test indicated that
the mean effect of BCAA supplementation on DOMS was subject to potential bias
(F[1,24]=18.322 [P<0.001]).
Sensitivity Analysis
Two of the 26 effects (7.7%) outside of the 95% confidence interval were identified using
the funnel plot to identify potential outliers. Sensitivity analysis removing these two effects
decreased the mean effect of BCAA supplementation on DOMS (ES=0.8041, 95% CI 0.6172 to
0.9910, p<0.001) for the remaining 24 effects.
Branched-chain amino acids and muscle soreness
The collective results of this analysis indicated that BCAA supplementation is an
effective method of reducing the exercise-induced DOMS, and appear consistent regardless of
sex and training status. The results of the current study add to the body of literature related to
BCAA supplementation and athletic performance. Collectively, BCAA supplementation appears
to have little ergogenic effect benefit when examining fatigue and exercise performance,
although there is some debate.[18, 19] Previous research indicated that BCAA supplementation
(50% leucine, 25% isoleucine, and 25% valine) prior to, and during exercise had little impact on
heart rate, core temperature, blood lactate concentration, or exercise performance during
prolonged cycling.[20] In addition, BCAA supplementation (30% leucine, 15% isoleucine, and
55% valine) did not appear to impact cognitive performance, mood, perceived exercise, comfort,
or exercise performance.[21] Although it appears that BCAA supplementation during exercise
may have little impact on performance per se, BCAA supplementation following training may
enhance recovery and reduce DOMS. The ergogenic benefits of enhanced recovery could
potentially allow for higher training frequency and greater volume accumulation, driving greater
long-term adaptations to training.
The mechanism by which BCAA’s reduce muscle tissue damage (thereby suppressing
DOMS) is understandable, though highly complex. It involves the interaction between leucine
and mechanistic target of rapamycin (mTOR) in the pathway of skeletal muscle protein synthesis
during the recovery phase, but is also mediated through the attenuation of muscle protein
breakdown during exercise. The increase in muscle soreness 24 to 48 hours following a bout of
resistance training, especially that with an emphasis on eccentric contraction, is typically
attributed to inflammation and myofibrillar damage.[22] Although all branch chain amino acids
are thought to play a role in skeletal muscle protein synthesis, leucine appears to have a greater
Branched-chain amino acids and muscle soreness
effect in regards to DOMS.[23] Ingestion of leucine shortly after a resistance training bout may
help to signal mTOR pathways that are responsible for the regulation of protein synthesis and
cell growth.[24] An increase in mTOR activation may help to accelerate the recovery process,
thus reducing the severity and duration of DOMS.
Additionally, leucine supplementation is thought to reduce proteolysis within skeletal
muscle, causing less damage to the sarcolemma.[25] Reductions in blood creatine kinase levels
following supplementation indicate a reduced inflammatory response, and may indicate
decreased muscle damage and accelerated recovery. Furthermore, short-term amino acid
supplementation during resistance training, including BCAAs, has been shown to increase
testosterone, and decrease cortisol and creatine kinase levels during periods of high-intensity
training, potentially providing an additional hormonal mechanism by which soreness could be
reduced and performance could be enhanced.[26]
These results provide the basis for ingesting a BCAA supplement while undergoing an
exercise training program for the prevention or reduction of DOMS. However, little research has
examined the effect of BCAA supplementation on DOMS in older adults, a population that could
provide significant advancements in the field of rehabilitation, geriatric medicine, and the overall
promotion of a better quality of life. Evidence suggests BCAA supplementation improves muscle
protein synthesis in older adults, which may provide a potential avenue for future research in this
population.[27, 28]
The results of the current study are not without limitation. It stands to reason that BCAA
supplementation would be most effective in suppressing DOMS and enhancing recovery in
untrained or minimally trained individuals. This is likely due to the fact that muscle performance
Branched-chain amino acids and muscle soreness
is enhanced in highly trained participants, which reduces pain-inflicting damage to muscle tissue
while also speeding the rate of recovery.[29] However, due to the relatively small body of
literature and relatively homogeneous populations studied, determining the effect of BCAA
supplementation in specific populations was beyond the scope of the current study. Future
research should focus on BCAA supplementation in middle-aged to elderly individuals (that are
seen fit for physical activity) participating in an intensive endurance or resistance training
program, in order to provide a more thorough meta-regression analysis, with statistical power
sufficient enough to determine the nature of BCAA interaction with aged skeletal muscle tissue.
In addition, the subjective primary outcome measure is not a direct indicator of muscle
damage, and is not linked to an objective or functional endpoint (body composition, performance
outcome, etc.). Furthermore, although dietary supplement research may claim to be ostensibly
'blinded' experiments, treatments are nonetheless often distinguishable by taste (as can be the
case for BCAA). The placebo effect can account for over two-thirds of improvements in
muscular performance, and over half of improvements in psychosocial outcomes following
exercise training.[30, 31] Our results are consistent with previous results indicating BCAA
supplementation can alleviate muscle soreness,[32] however this previous review was also
limited to placebo-controlled trials. These previous results, and our current results, did not
compare BCAA supplementation to whole proteins or other dietary supplements. Even in light of
our current findings that indicated BCAA supplementation can reduce DOMS following
exercise, this study has only compared BCAAs to a placebo supplement or “nothing at all”
Furthermore, our results are limited to recovery following a single bout of strenuous exercise,
and should not be extended to imply that improvements in muscular strength, performance, or
body composition would occur following a structured exercise training program. Dietary
Branched-chain amino acids and muscle soreness
supplements such as BCAA, are indeed just that, “supplements.” In that sense, BCAA
supplementation alone cannot support an increased rate of muscular protein synthesis,[33] and it
is our recommendation that dietary supplements should be used to “supplement” or compliment
a well-balanced diet that includes adequate amounts of dietary protein.[34] Finally, it is also
assumed that the magnitude of the effect should vary by time of ingestion, amount ingested, ratio
of specific amino acids, intensity of the exercise training program utilized, and many other
possible factors. Again, because of the relatively small body of literature and relatively
homogeneous populations studied, examining these potential moderators was not possible.
However, the results of this analysis strengthen the notion that some benefit will inherently be
seen, regardless of these factors, in untrained individuals.
Based on the cumulative results from peer-reviewed cross-over and randomized
controlled trials published between 2007 and 2013, it was determined that supplementation of
BCAA supplementation has a large effect on DOMS, as well as the rate of muscle tissue
recovery thereafter. Measurable improvements in DOMS will provide a considerable benefit to
athletes, as well as health and fitness professionals seeking to mitigate soreness and potentially
improve performance.
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Branched-chain amino acids and muscle soreness
Table 1. Study summary and quality assessment of branched-chain amino acid supplementation on delayed onset muscle soreness.
Source Summary Randomization Blinding Withdrawal Total Score
Greer et al. 2007 Nine untrained male participants
(21.6±3.2 yrs., 26.3.2±4.3 kg/m2)
completed three 90 minute cycling
bouts at 55% of VO2max and ingested
a placebo, carbohydrate, or BCAA
supplement as part of the study
protocol using a cross-over design.
The 2.5 g BCAA supplement
contained 480 mg isoleucine, 1.22 g
leucine, and 730 mg valine. Self-
reported muscle soreness of the
quadriceps was assessed using a 1 to
10 scale at 24 and 48 hours after
0 0 0 0
Howatson et al. 2012 Twelve resistance-trained male
participants (23±2 yrs.) were
randomly assigned to a placebo or
BCAA group and engaged in a
single bout of plyometric exercise
consisting of 100 drop jumps. The
10 g BCAA supplement consisted of
isoleucine, leucine, and valine in a
1:2:1 ratio.
Muscle soreness was assessed
using a 200 mm visual
analogue scale while
participants held a squatting
position (90°) at 24, 48, 72,
and 96 hours following
1 2 0 3
Jackman et al. 2010 Twenty-four untrained male 0 0 0 0
Branched-chain amino acids and muscle soreness
participants were assigned to a
placebo or BCAA group and
engaged in a resistance training
protocol consisting of eccentric
unilateral knee extensions. The
BCAA supplement consisted of 2.1
g of isoleucine, 3.5 g of leucine, and
1.7 g of valine. Muscle soreness was
assessed using a 50 mm visual
analogue scale while the knee was
flexed and extended at 24, 48, and
72 hours following exercise.
Ra et al. 2013 Thirty-six untrained male
participants (22.5±3.8 yrs.)
were randomly assigned to
a placebo, BCAA, Taurine,
or BCAA+Taurine
supplement group and
engaged in a high-intensity
eccentric resistance
training exercise bout. The
3.2 g BCAA supplement
consisted of isoleucine,
leucine, and valine in a
1:2:1 ratio. Self-reported
muscle soreness of the
biceps brachii was assessed
using a 100 mm visual
analogue scale with
anchored with “no pain”
and “extreme pain” at
opposite poles at 24, 48,
72, and 96 hours following
1 2 0 3
Branched-chain amino acids and muscle soreness
Shimomura et al. 2010 Twelve untrained female
participants (22.5±3.8 yrs.)
participated in a cross-over double-
blind experimental protocol
ingesting a placebo or BCAA
supplement and engaging in a lower-
body resistance training protocol.
The BCAA supplement consisted of
isoleucine, leucine, and valine in a
1:2.3:1.2 ratio. Participants were
asked to report muscle soreness of
the lower limbs while squatting
slowly using a 100 mm visual
analogue scale at 24, 48, 72, and 96
hours following exercise.
1 2 0 3
Note: Data are presented as mean±standard deviation. BCAA= branched-chain amino acid, VO2max=Aerobic capacity.
Branched-chain amino acids and muscle soreness
Table 2. Summary of subgroup analysis of the daily changes in DOMS following an acute bout
of exercise.
Effects (κ) Mean ES 95% CI p value Between
p value
Time Point
1 Day 9 0.7878 0.4865,
<0.0001 0.1266
2 Days 7 1.1286 0.1886,
3 Days 6 0.8458 0.4673,
4 Days 4 0.6514 0.1726,
Note: ES=Effect size. CI= Confidence Interval.
... Commercial BCAA supplements are commonly preferred in sports activities due to their muscle-related effects. BCAAs are claimed to have several functions as an ergogenic aid in sports, such as increasing muscle mass by activating protein synthesis, strengthening immunity, reducing soreness, improving cognitive function, and enhancing endurance capacity [4][5][6][7][8][9][10]. However, there are not enough studies in the literature to confirm most of these claims [4][5][6][7][8]. ...
... In addition, good (n = 1824), like (n = 1650), and great (n = 1211), which are the most-used words in video comments, support this finding. The investigated comments could be related to the potential effects of BCAAs, such as activating protein synthesis, reducing soreness, enhancing cognitive activity, boosting immunity, and improving endurance capacity [4][5][6][7][8][9][10]. In fact, the words protein (n = 3378) and muscle (n = 1422) are often emphasized in video comments. ...
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Branched-chain amino acids (BCAAs) are one of the most controversial ergogenic aids in terms of effectiveness and safety. This study aimed to evaluate the quality and reliability of BCAA supplements related to English videos on YouTube and to synthesize with the sentiment-emotion analysis of comments on videos. The content analysis of the information on videos was evaluated with the use of DISCERN, Journal of American Medical Association (JAMA) benchmark criteria, and Global Quality Score (GQS). In addition, word cloud and sentiment and emotional analysis of comments in videos were performed with the R package. As a result, the mean ± standard error values of DISCERN, JAMA, and GQS scores of all videos were 29.27 ± 1.97, 1.95 ± 0.12, and 2.13 ± 0.17, respectively. It was found that advertisement-free videos have a significantly higher DISCERN and GQS score than advertisement-included videos (p < 0.05). A moderately significant positive correlation was determined between DISCERN score of video content and the positive sentiment of video comments (rs: 0.400, p = 0.002). In conclusion, it was determined that BCAA-related YouTube videos have mostly very poor quality in terms of content and that videos with higher quality may receive positive comments from viewers according to the DISCERN instrument.
... However, no signi cant difference was noted in tumor recurrence rate and overall survival rate between the groups. BCAA enrichment formulas used were similar to supplemental parenteral nutrition, and BCAA supplementation changed the adipose-muscle-liver triangle in the metabolic pathway, for example, delayed-onset muscle soreness [21,22], insulin resistance of type 2 diabetes, decreased obesity risk [23], and clinical side effect of hepatic encephalopathy. Ooi et al. revealed that 40 studies on BCAA supplementation in adults with liver cirrhosis showed improvement in muscle strength, ascites, and edema, whereas children with liver cirrhosis showed improvement in body weight, fat mass, fat-free mass, and serum albumin level [24]. ...
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BACKGROUND: The benefits of branched-chain amino acid (BCAA) administration after hepatic intervention in patients with liver diseases remains unclear. We conducted a systematic review and meta-analysis to evaluate the effects of BCAA on patients undergoing hepatectomy, trans-arterial embolization, radiofrequency ablation. METHODS: Relevant randomized controlled trials (RCTs) were obtained from PubMed, EMBASE, and Cochrane Library databases. A meta-analysis was performed to calculate the pooled effect size by using random-effects models. The primary outcomes were survival, hospital stay, nutrition status, and biochemistry profile. The secondary outcomes were the complication rate of liver treatment and adverse effect of BCAA supplementation. RESULTS: In total, 11 RCTs involving 750 patients were included. Our meta-analysis showed no significant difference in the rates of tumorrecurrence and overall survival between the BCAA and control groups. However, the pooled estimate showed that BCAA supplementation in patients undergoing hepatic intervention significantly increased serum albumin (mean difference [MD]: 0.11 g/dL, 95% confidence interval [CI]: 0.02–0.20) at 6 months and cholinesterase level (MD: 50.00 U/L, 95% CI: 21.08–78.92) at 12 months, increased body weight (MD: 3.29 kg, 95% CI: 1.07–5.50) at 12 months, and reduced ascites incidence (risk ratio: 0.39, 95% CI: 0.21–0.71) compared with the control group. Additionally, BCAA administration shortened the hospital stay length (MD: −2.36 days, 95% CI: −4.78 to 0.07) compared with the control group. CONCLUSION: BCAA supplementation significantly reduced postintervention complication and hospitalization duration and increased body weight. Thus, BCAA supplementation may benefit patients undergoing liver intervention.
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This study aimed to evaluate the effects of ingesting yogurt fermented with Lactobacillus delbrueckii subsp. bulgaricus (OLL1073R-1) on the immune function of healthy university men track and field athletes. Study design Randomized, double-blind, placebo-controlled, parallel-group study. A total of 37 track and field athletes aged ≥18 years were randomly assigned into two groups. For 2 weeks, two bottles of yogurt fermented with OLL1073R-1 and Streptococcus thermophilus OLS3059 or placebo sour milk were ingested daily to the participants. During the intake period, a 1-week training camp was held and participants were subjected to strenuous exercise. Natural killer (NK) cell activity, which is the primary endpoint, was significantly lower in the placebo group after ingestion than that at baseline; however, it remained unchanged during the pre-exercise level of the yogurt group. The two-way repeated measures analysis of variance showed an interaction effect in the NK cell activity change (P=0.018) and a significant difference between the groups after the 2-week ingestion (P=0.015). Among the secondary endpoints, cytokines and chemokines levels involved in activating innate immunity maintained or enhanced only in the yogurt group. ALT, LDH, and CK significantly elevated only in the placebo group. Furthermore, amino acid levels were significantly lower in the placebo group after ingestion than that at baseline; however, it remained unchanged during the pre-exercise level in the yogurt group. Consuming yogurt fermented with OLL1073R-1 prevents the decline in immune function associated with strenuous exercise. Additionally, the yogurt may contribute to stable physical condition.
Female athletes tend to choose their supplements for different reasons than their male counterparts. Collegiate female athletes report taking supplements “for their health,” to make up for an inadequate diet, or to have more energy. Multivitamins, herbal substances, protein supplements, amino acids, creatine, fat burners/weight-loss products, caffeine, iron, and calcium are the most frequently used products reported by female athletes. Many female athletes are unclear on when to use a protein supplement, how to use it, and different sources of protein (animal vs. plant-based). This chapter addresses protein supplementation, amino acid supplementation, and creatine. In this chapter we also address the reported performance benefits, if any, of Echinacea, ginseng, caffeine, energy drinks, pre-workouts, and iron. The chapter concludes with a discussion on contamination of supplements and banned substances for competition. Competitive athletes should be aware of the banned substance list for their governing body and that over the counter (OTC) nutritional supplement products are not currently regulated by the food and drug administration (FDA). This lack of regulation may lead to supplements that are contaminated with banned substances.
Micronutrients, particularly amino acids, are thought to play an important role in sleep regulation and maintenance. While tryptophan is a known predictor of sleep, less is known about branched-chain amino acids (BCAAs), which compete with tryptophan for transport across the blood-brain barrier. The aim of this study was to determine the association between BCAAs and actigraphy-derived sleep duration, timing and efficiency, and self-reported trouble sleeping. This study examined data on children and adults collected as part of the Child Health CheckPoint study. Linear mixed models, adjusted for geographic clustering, were used to determine the association between BCAAs and sleep characteristics. Complete-case analysis was conducted for 741 children aged 11-12 years old (51% females) and 941parents (87% mothers). While BCAAs were significantly associated with children's sleep duration, timing and self-reported trouble sleeping, no associations were observed in adults, in fully adjusted models. In children, higher levels of BCAAs are associated with shorter sleep duration, delayed sleep timing, and more frequent reports of trouble sleeping.
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Background& purpose: Today, among athletes, the use of amino acid supplements with the aim of reducing muscle injuries is more important than in the past. the aim of this study was to survey the effect of branched chain amino acids (BCAA) consumption before exhaustive exercise along with 1-month vitamin E supplementation on lactate dehydrogenase (LDH) and creatine kinase (CK) levels of active females. Methods: 32 active female students of Raazi University, with 18-23 years of age were selected based on the study eligibility criteria and were divided into four groups of eight (placebo, Vit E, BCAA, and Vit E-BCAA), randomly. Vit E was consumed as 400 IU daily for a month and BCAA was consumed from 2.5 hours before exercise session in 4 bouts 30 minutes apart. Exercise protocol was consisted of 30 minutes pedaling on ergometer with 50% of the aerobic power, and immediately continued with 75% of the aerobic power until the exhaustion. Sampling was done immediately and 48 hours after the exercise session and data were analyzed using SPSS 22 (α = 0.05). Results: none of supplements had effect on immediate levels of LDH and CK (P > .05) but the mean levels of LDH and CK, 48 hours post exercise was lower in BCAA and BCAA-Vit E compared to Vit E and placebo groups (P = .001) and the BCAA-Vit E showed lower levels that was negatively correlated to plasma leucine and isoleucine levels (P = .001). Conclusion: although BCAA alone decreased post exercise muscular damage indices, but it seems that leucine and isoleucine along with Vit E supplementation have more effect on muscular damage.
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Advanced nutritional interventions are one of the key components of elite sports performance in general. Combat sports require a high percentage of muscle mass with minimum body weight to generate the maximum power possible. An adequate level of nutrition knowledge, particularly with respect to identifying energy needs while avoiding confusion over dietary supplements and false perceptions of steroid requirement, which may compromise the health condition, is of crucial importance. In this context, the aim of our work is to highlight nutritional require-ments/nutritional assessment, the importance of daily dietary intake in combat players, which increasingly includes a broad range of sports nutrition supplements, and the roles of vitamins, minerals and proteins, combined with antioxidants and strength training, in muscular performance. The main nutrients required in the daily diet of combat players, the mechanisms of action, the main outcomes and possible side effects are summarized. Special attention is paid to natural supplements and their importance and advantages over synthetic ones, along with future trends of development.
Laser exposure stimulates cell proliferation and tissue repair. Branched-chain amino acids (BCAA) are widely used in sports medicine as a stimulator of anabolic processes. However, there is no evidence of the effect of combined laser and BCAA application on skeletal muscle morphometric characteristics during exercise in the training process. Purpose: to study the effect of infrared laser exposure in combination with amino acid at myosatellitocytes and skeletal muscle myocytes during swimming training. Material and methods . The experiment was conducted on 30 Wistar rats: Group 1 – intact, Group 2 – dynamic control (trainings with endurance swimming), Group 3 – trainings and BCAA, Group 4 – trainings and laser exposure at hip muscles (970 nm, 1 W, 60 s), Group 5 – combined exposure to laser and BCAA. Trainings were three times a week for 6 weeks; laser session was after each training. Samples of the bipedal thigh muscle were fixed with formalin; histological sections were stained with hematoxylin-eosin. The morphometric analysis of the digital image of objects with statistical processing by Mann – Whitney method was made. Results. Laser exposure combined with BCAA during trainings increased the nuclei area and the number of myosatellites and myocytes; it also enlarged the cross section of muscle fibers which was more pronounced if to compare with isolated laser irradiation of the muscle or BCAA. Conclusions. Infrared laser exposure in combination with branched-chain amino acids effectively stimulates regeneration due to hyperplasia and hypertrophy of skeletal muscular tissue, thus providing physiological adaptation in the training process.
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[Purpose] Exercise guidance is an effective measure against locomotive syndrome. Appropriate nutritional management is also considered necessary in order to maintain the motor function. This study is the first exploratory and prospective research on the effects of exercise guidance and feeding high-protein foods in order to improve locomotive syndrome, in elderly people. [Method] We conducted a survey regarding five items related to locomotorium on the basic checklist prepared by the Japanese Ministry of Health, among men and women in their 60s and over living in Miyazaki Prefecture. Participation was solicited from those who responded “applicable” to three or more items, with those who gave their consent assigned to a food + exercise intervention group (EF group), an exercise intervention group (EX group), and a control group (C group) for research. Motor function surveys such as interviews, questionnaire, and locomotive syndrome risk test were conducted at the start of the study and three months later. The EX and EF groups were instructed to carry out locomotion training, while the EF group was asked to ingest one bag of high-protein test food daily immediately following exercise. The participants carried an activity meter and kept a record of their life in a diary during the study period. The EX and EF groups were encouraged to make recordings in a diary and carry an activity meter, while also getting a regular telephone contact once a week. [Results] An improvement in the motor function was observed in the EX and EF group compared to the C group via Locomotive syndrome risk testing. While the muscle mass decreased significantly during the study period in the C and EX group, no significant change was observed in limbs/trunk muscle mass in the EF group. [Conclusion] The locomotion training improved the results of the Locomotive syndrome risk testing. Although muscle mass decreased with exercise guidance alone, muscle mass loss was suppressed by feeding high-protein foods in addition to exercise. We conclude that feeding high-protein foods is useful for improving motor function and maintaining muscle mass, in addition to exercise guidance, as a measure against locomotive syndrome in elderly.
Objectives To evaluate the efficacy of low-intensity focused ultrasound (LIFU) treatment on rapid relief of delayed-onset muscle soreness (DOMS) triggered by high-intensity exercise. Methods A total of 16 healthy male college students were randomly divided into two groups: the LIFU group (n = 8) and the Sham group (n = 8). After the exercise protocol, the LIFU group received treatment, which parameters included that the power output was 2.5 W/cm², the frequency was 1 MHz, and the treating time was 20 minutes. The Sham group was treated with LIFU without energy output. Visual analog scale was used to evaluate the level of DOMS in every participant. The activities of plasma creatine kinase, lactate dehydrogenase, and the plasma concentration were measured by spectrophotometry. Tumor necrosis factor-α and interleukin-6 of serum were analyzed by enzyme-linked immunosorbent assay. Results The visual analog scale of quadriceps femoris and/or calf muscles in the LIFU group decreased significantly at 24 hours (P < 0.01) and 48 hours (P < .01) after the exercise protocol. Both the accumulation of lactic acid (P < .01) in muscle and the activity of lactate dehydrogenase (P < .01) reduced immediately after LIFU treatment. The activities of tumor necrosis factor-α and interleukin-6 24 hours lowered in the LIFU group (P < .01). Conclusions LIFU treatment could relieve muscle soreness rapidly and effectively in the early stages of DOMS. The application of LIFU may provide a potential strategy for clinical treatment for DOMS.
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Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the management of micronutrient deficiencies, (2) supply of convenient forms of energy and macronutrients, and (3) provision of direct benefits to performance or (4) indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can benefit the athlete, but others may harm the athlete’s health, performance, and/or livelihood and reputation (if an antidoping rule violation results). A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome and habitual diet. Supplements intended to enhance performance should be thoroughly trialled in training or simulated competition before being used in competition. Inadvertent ingestion of substances prohibited under the antidoping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete’s health and awareness of the potential for harm must be paramount; expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.
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Amino acids and more precisely, branched-chain amino acids (BCAAs), are usually consumed as nutritional supplements by many athletes and people involved in regular and moderate physical activities regardless of their practice level. BCAAs have been initially shown to increase muscle mass and have also been implicated in the limitation of structural and metabolic alterations associated with exercise damage. This systematic review provides a comprehensive analysis of the literature regarding the beneficial effects of BCAAs supplementation within the context of exercise-induced muscle damage or muscle injury. The potential benefit of a BCAAs supplementation was also analyzed according to the supplementation strategy—amount of BCAAs, frequency and duration of the supplementation—and the extent of muscle damage. The review protocol was registered prospectively with Prospective Register for Systematic Reviews (registration number CRD42017073006) and followed Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Literature search was performed from the date of commencement until August 2017 using four online databases (Medline, Cochrane library, Web of science and ScienceDirect). Original research articles: (i) written in English; (ii) describing experiments performed in Humans who received at least one oral BCAAs supplementation composed of leucine, isoleucine and valine mixture only as a nutritional strategy and (iii) reporting a follow-up of at least one day after exercise-induced muscle damage, were included in the systematic review analysis. Quality assessment was undertaken independently using the Quality Criteria Checklist for Primary Research. Changes in indirect markers of muscle damage were considered as primary outcome measures. Secondary outcome measures were the extent of change in indirect markers of muscle damage. In total, 11 studies were included in the analysis. A high heterogeneity was found regarding the different outcomes of these studies. The risk of bias was moderate considering the quality ratings were positive for six and neutral for three. Although a small number of studies were included, BCAAs supplementation can be efficacious on outcomes of exercise-induced muscle damage, as long as the extent of muscle damage was low-to-moderate, the supplementation strategy combined a high daily BCAAs intake (>200 mg kg−1 day−1) for a long period of time (>10 days); it was especially effective if taken prior to the damaging exercise.
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The branched chain amino acids (BCAAs) are leucine, valine and isoleucine. A multi-million dollar industry of nutritional supplements has grown around the concept that dietary supplements of BCAAs alone produce an anabolic response in humans driven by a stimulation of muscle protein synthesis. In this brief review the theoretical and empirical bases for that claim are discussed. Theoretically, the maximal stimulation of muscle protein synthesis in the post-absorptive state in response to BCAAs alone is the difference between muscle protein breakdown and muscle protein synthesis (about 30% greater than synthesis), because the other EAAs required for synthesis of new protein can only be derived from muscle protein breakdown. Realistically, a maximal increase in muscle protein synthesis of 30% is an over-estimate because the obligatory oxidation of EAAs can never be completely suppressed. An extensive search of the literature has revealed no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed. Both of these intravenous infusion studies found that BCAAs decreased muscle protein synthesis as well as protein breakdown, meaning a decrease in muscle protein turnover. The catabolic state in which the rate of muscle protein breakdown exceeded the rate of muscle protein synthesis persisted during BCAA infusion. We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.
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Objective We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength. Data sources A systematic search of Medline, Embase, CINAHL and SportDiscus. Eligibility criteria Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation. Design Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM). Results Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength—one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size—muscle fibre cross-sectional area (CSA; 310 µm² (51, 570)) and mid-femur CSA (7.2 mm² (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (−0.01 kg (−0.02,–0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM. Summary/conclusion Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.
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Background Amino acid supplementation has been shown to potentially reduced exercise-induced muscle soreness. Thus, the purpose of this study was to examine if branched chain amino acid and carbohydrate (BCAACHO) versus carbohydrate-only sports drink (CHO) supplementation attenuated markers of muscle damage while preserving performance markers following 3 days of intense weight training. Methods Healthy resistance-trained males (n = 30) performed preliminary testing (T1) whereby they: 1) donated a baseline blood draw, 2) performed knee extensor dynamometry to obtain peak quadriceps isometric and isokinetic torque as well as electromyography (EMG) activity at 60°/s and 120°/s, and 3) performed a one repetition maximum (1RM) barbell back squat. The following week participants performed 10 sets x 5 repetitions at 80 % of their 1RM barbell back squat for 3 consecutive days and 48 h following the third lifting bout participants returned for (T2) testing whereby they repeated the T1 battery. Immediately following and 24 h after the three lifting bouts, participants were randomly assigned to consume one of two commercial products in 600 mL of tap water: 1) BCAAs and CHO (3 g/d L-leucine, 1 g/d L-isoleucine and 2 g/d L-valine with 2 g of CHO; n = 15), or 2) 42 g of CHO only (n = 15). Additionally, venous blood was drawn 24 h following the first and second lifting bouts and 48 h following the third bout to assess serum myoglobin concentrations, and a visual analog scale was utilized prior, during, and after the 3-d protocol to measure subjective perceptions of muscular soreness. Results There were similar decrements in 1RM squat strength and isokinetic peak torque measures in the BCAA-CHO and CHO groups. Serum myoglobin concentrations (p = 0.027) and perceived muscle soreness (p < 0.001) increased over the intervention regardless of supplementation. A group*time interaction was observed for monocyte percentages (p = 0.01) whereby BCAA-CHO supplementation attenuated increases in this variable over the duration of the protocol compared to CHO supplementation. Conclusion BCAA-CHO supplementation did not reduce decrements in lower body strength or improve select markers of muscle damage/soreness compared to CHO supplementation over three consecutive days of intense lower-body training.
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The provision of sufficient amounts of dietary proteins is central to muscle health as it ensures the supply of essential amino acids and stimulates protein synthesis. Older persons, in particular, are at high risk of insufficient protein ingestion. Furthermore, the current recommended dietary allowance for protein (0.8 g/kg/day) might be inadequate for maintaining muscle health in older adults, probably as a consequence of “anabolic resistance” in aged muscle. Older individuals therefore need to ingest a greater quantity of protein to maintain muscle function. The quality of protein ingested is also essential to promoting muscle health. Given the role of leucine as the master dietary regulator of muscle protein turnover, the ingestion of protein sources enriched with this essential amino acid, or its metabolite β-hydroxy β-methylbutyrate, is thought to offer the greatest benefit in terms of preservation of muscle mass and function in old age.
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Eccentric exercise results in prolonged muscle damage that may lead to muscle dysfunction. Although inflammation is essential to recover from muscle damage, excessive inflammation may also induce secondary damage, and should thus be suppressed. In this study, we investigated the effect of leucine-enriched essential amino acids on muscle inflammation and recovery after eccentric contraction. These amino acids are known to stimulate muscle protein synthesis via mammalian target of rapamycin (mTOR), which, is also considered to alleviate inflammation. Five sets of 10 eccentric contractions were induced by electrical stimulation in the tibialis anterior muscle of male SpragueDawley rats (8-9 weeks old) under anesthesia. Animals received a 1 g/kg dose of a mixture containing 40 % leucine and 60 % other essential amino acids or distilled water once a day throughout the experiment. Muscle dysfunction was assessed based on isometric dorsiflexion torque, while inflammation was evaluated by histochemistry. Gene expression of inflammatory cytokines and myogenic regulatory factors was also measured. We found that leucine-enriched essential amino acids restored full muscle function within 14 days, at which point rats treated with distilled water had not fully recovered. Indeed, muscle function was stronger 3 days after eccentric contraction in rats treated with amino acids than in those treated with distilled water. The amino acid mix also alleviated expression of interleukin-6 and impeded infiltration of inflammatory cells into muscle, but did not suppress expression of myogenic regulatory factors. These results suggest that leucine-enriched amino acids accelerate recovery from muscle damage by preventing excessive inflammation.
Objective Accumulating evidences suggest positive effects of BCAAs on moderate muscle damage. However, findings vary substantially across studies. The aim of this review was to examine the effect of branched chain amino acids (BCAA) on recovery following exercise induced muscle damage (EIMD). Methods Controlled trials were identified through computerized literature searching and citation tracking performed up to November 2015. To pool data, either a fixed-effects model or a random-effects model and for assessing heterogeneity, Cochran's Q and I² tests were used. Results Eight trials met the inclusion criteria. Pooled data from eight studies showed that BCAA significantly reduced Creatine Kinase (CK) at two follow-up time (<24 and 24 hours) in comparison with placebo recovery(<24h: MD= -71.55 U.L⁻¹, 95% CI: -93.49 to -49.60, p< 0.000, n=5 trials and 24h: MD= -145.04 U.L⁻¹, 95% CI: -253.66 to -36.43, p = 0.009 n=8 trials). In contrast, effects were not significant in any of the follow-up times for muscle soreness (MS) and lactate dehydrogenase (LDH). Conclusion The current evidence based information offer that BCAA is better than using passive recovery or rest after various forms of exhaustive and damaging exercise. The advantages relate to a reduction in MS, and ameliorated muscle function because of an attenuation of muscle strength and muscle power loss after exercise.
This study investigated the effects of acute branched-chain amino acid (BCAA) supplementation on recovery from exercise-induced muscle damage, among experienced resistance-trained athletes. In a double-blind matched-pairs design, 16 resistance-trained participants, routinely performing hypertrophy training, were randomly assigned to a BCAA (n = 8) or placebo (n = 8) group. The BCAAs were administered at a dosage of 0.087 g/kg body mass, with a 2:1:1 ratio of leucine, isoleucine and valine. The participants performed 6 sets of 10 full-squats at 70 % 1RM to induce muscle damage. All participants were diet-controlled across the study. Creatine kinase (CK), peak isometric knee-extensor force, perceived muscle soreness and counter-movement jump (CMJ) height were measured immediately before (baseline), 1-h, 24-h and 48-h post-exercise. There were large to very large time effects for all measurements between baseline and 24-48 h. Between-group comparisons, expressed as a percentage of baseline, revealed differences in isometric strength at 24-h (Placebo ~87% c.f. BCAA ~92 %; moderate, likely), CMJ at 24-h (Placebo ~93 % c.f. BCAA ~96 %; small, likely) and muscle soreness at both 24-h (Placebo ~685 % c.f. BCAA ~531 %; small, likely) and 48-h (Placebo ~468 % c.f. BCAA ~350 %; small, likely). Acute supplementation of BCAAs (0.087 g/kg) increased the rate of recovery in isometric strength, CMJ height and perceived muscle soreness compared to placebo after a hypertrophy-based training session among diet-controlled, resistance-trained athletes. These findings question the need for longer BCAA loading phases and highlight the importance of dietary control in studies of this type.
This paper is a meta-analysis of the role of nutritional supplements in strength training focusing on the effects of placebo treatments. We address specifically the results from meta-analysis of 334 fi.ndings from 37 studies of the effect of nutritional supplements and physical fitness interventions on strength, stamina, and endurance outcomes, controlling for main effects of the group on which the results were obtained (placebo, treatment, control, for pretest or posttest), with covariates for age, gender, randomization, double-blind procedures, study duration, training load, training frequency, and training status. Finding show that there are significant placebo effects accounting for a substantial portion of the effect size typically associated with treatment interventions. In addition to produce the best evaluations of treatment effects, both control and placebo groups should be included in a double-blind research design using participants who are well familiarized with the study procedures.