madman
Super Moderator
ABSTRACT
Objective
This overview of systematic reviews (OoSRs) aimed, firstly, to systematically review,summarize, and appraise the findings of published systematic reviews with or without meta-analyses that investigate the effects of branched-chain amino acids (BCAA) on post-exercise recovery of muscle damage biomarkers, muscle soreness, and muscle performance. The secondary objective was to re-analyze and standardize the results of meta-analyses using the random-effects Hartung-Knapp-Sidik-Jonkman (HKSJ) method.
Methods
The methodological quality of the reviews was assessed using A Measurement Tool to Assess Systematic Reviews 2.We searched on five databases (i.e., PubMed, Web of Science, Scopus,SPORTDiscus, ProQuest) for systematic reviews with or without meta-analyses that investigated the effects of BCAA supplementation on the post-exercise recovery of muscle damage biomarkers,muscle soreness, and muscle performance.
Results
Eleven systematic reviews (seven with meta-analyses) of individual studies were included.Evidence suggests BCAA ingestion attenuates creatine kinase (CK) levels (medium effects) and muscle soreness (small effects) immediately post-exercise and accelerates their recovery process,with trivial-to-large effects for CK levels and small-to-large effects for muscle soreness. BCAA supplementation has no effect on lactate dehydrogenase, myoglobin, and muscle performance recovery. The re-analyses with HKSJ method using the original data reported a slight change in results significance, concluding the same evidence as the original results. The major flaws found in the analyzed reviews were the absence of justification for excluding studies, and the lack of provision of sources of funding for primary studies and sources of conflict of interest and/or funding description.
Conclusions
BCAA supplementation is an effective method to reduce post-exercise muscle damage biomarkers, particularly CK levels, and muscle soreness, with no effect on muscle performance.Future systematic reviews with/without meta-analyses, with greater methodological rigor, are needed.
Introduction
Branched-chain amino acids (BCAA: leucine, isoleucine, and valine) comprise almost 50% of all EAAs in food and 35%of the total content of essential amino acids (EAAs) in muscle proteins (1, 2). Moreover, BCAA components are catabolized initially in skeletal muscle, while other amino acids are catabolized in the liver (1). BCAA play a crucial role in muscle growth and repair (3) and are commonly supplemented by athletes and bodybuilders to enhance performance and promote muscle hypertrophy (3).
One of the most well-established effects of BCAA supplementation is the ability to enhance muscle protein synthesis (MPS) (4), which is the process by which muscle fibers repair and grow after exercise (4). Therefore, BCAA directly regulate protein turnover in muscle cells, reversing the catabolic and anti-anabolic consequences of exercise-included muscle damage (EIMD) (5). Leucine (6), in particular, is identified as (i) a crucial regulator of mTOR signaling and translation initiation (7) and (ii) a possible promoter in the recovery process of damaged muscle tissues (8). Additionally, BCAA are major precursors of tricarboxylic acid cycle intermediates via acetyl-CoA and succinyl-CoA (9). BCAA can also be used as an energy source during endurance exercise(10) and can similarly reduce the muscle damage resulting from intense exercise (11). BCAA supplementation also reduces muscle soreness and inflammation (12), which can reduce recovery time after EIMD. This may be due to BCAA ability to decrease enzyme levels and inflammatory markers associated with muscle damage (12). BCAA supplementation may improve physical performance and recovery between workouts, potentially leading to improved exercise performance (13).
Conclusion
BCAA supplementation is an effective strategy to reduce post-exercise muscle damage biomarkers (i.e., CK levels) and muscle soreness. The magnitude of the effectiveness of BCAA supplementation is generally greater in reducing post-exercise CK levels and muscle soreness than in reducing post-exercise LDH. BCAA supplementation has no effect on post-exercise muscle performance recovery. Future SRs with/without meta-analyses should have higher methodological rigor. This includes providing a list of excluded studies and registering protocols in a specific database. Therefore, coaches and athletes should take the following into consideration: (i) if athletes train four times a week, BCAA supplementation may aid in recovery between training sessions due to the positive effects of BCAA at both less than 24 h and 24 h post-exercise.However, if they train only three times a week, supplementation is not suggested, (ii) supplementation of BCAA, both in low and high doses, for an extended period, could be an effective strategy for recovering from muscle damage induced by EIMD, (iii) and consuming BCAA before exercise or a training session has more beneficial effects on muscle damage biomarkers, as well as on muscle soreness.
Objective
This overview of systematic reviews (OoSRs) aimed, firstly, to systematically review,summarize, and appraise the findings of published systematic reviews with or without meta-analyses that investigate the effects of branched-chain amino acids (BCAA) on post-exercise recovery of muscle damage biomarkers, muscle soreness, and muscle performance. The secondary objective was to re-analyze and standardize the results of meta-analyses using the random-effects Hartung-Knapp-Sidik-Jonkman (HKSJ) method.
Methods
The methodological quality of the reviews was assessed using A Measurement Tool to Assess Systematic Reviews 2.We searched on five databases (i.e., PubMed, Web of Science, Scopus,SPORTDiscus, ProQuest) for systematic reviews with or without meta-analyses that investigated the effects of BCAA supplementation on the post-exercise recovery of muscle damage biomarkers,muscle soreness, and muscle performance.
Results
Eleven systematic reviews (seven with meta-analyses) of individual studies were included.Evidence suggests BCAA ingestion attenuates creatine kinase (CK) levels (medium effects) and muscle soreness (small effects) immediately post-exercise and accelerates their recovery process,with trivial-to-large effects for CK levels and small-to-large effects for muscle soreness. BCAA supplementation has no effect on lactate dehydrogenase, myoglobin, and muscle performance recovery. The re-analyses with HKSJ method using the original data reported a slight change in results significance, concluding the same evidence as the original results. The major flaws found in the analyzed reviews were the absence of justification for excluding studies, and the lack of provision of sources of funding for primary studies and sources of conflict of interest and/or funding description.
Conclusions
BCAA supplementation is an effective method to reduce post-exercise muscle damage biomarkers, particularly CK levels, and muscle soreness, with no effect on muscle performance.Future systematic reviews with/without meta-analyses, with greater methodological rigor, are needed.
Introduction
Branched-chain amino acids (BCAA: leucine, isoleucine, and valine) comprise almost 50% of all EAAs in food and 35%of the total content of essential amino acids (EAAs) in muscle proteins (1, 2). Moreover, BCAA components are catabolized initially in skeletal muscle, while other amino acids are catabolized in the liver (1). BCAA play a crucial role in muscle growth and repair (3) and are commonly supplemented by athletes and bodybuilders to enhance performance and promote muscle hypertrophy (3).
One of the most well-established effects of BCAA supplementation is the ability to enhance muscle protein synthesis (MPS) (4), which is the process by which muscle fibers repair and grow after exercise (4). Therefore, BCAA directly regulate protein turnover in muscle cells, reversing the catabolic and anti-anabolic consequences of exercise-included muscle damage (EIMD) (5). Leucine (6), in particular, is identified as (i) a crucial regulator of mTOR signaling and translation initiation (7) and (ii) a possible promoter in the recovery process of damaged muscle tissues (8). Additionally, BCAA are major precursors of tricarboxylic acid cycle intermediates via acetyl-CoA and succinyl-CoA (9). BCAA can also be used as an energy source during endurance exercise(10) and can similarly reduce the muscle damage resulting from intense exercise (11). BCAA supplementation also reduces muscle soreness and inflammation (12), which can reduce recovery time after EIMD. This may be due to BCAA ability to decrease enzyme levels and inflammatory markers associated with muscle damage (12). BCAA supplementation may improve physical performance and recovery between workouts, potentially leading to improved exercise performance (13).
Conclusion
BCAA supplementation is an effective strategy to reduce post-exercise muscle damage biomarkers (i.e., CK levels) and muscle soreness. The magnitude of the effectiveness of BCAA supplementation is generally greater in reducing post-exercise CK levels and muscle soreness than in reducing post-exercise LDH. BCAA supplementation has no effect on post-exercise muscle performance recovery. Future SRs with/without meta-analyses should have higher methodological rigor. This includes providing a list of excluded studies and registering protocols in a specific database. Therefore, coaches and athletes should take the following into consideration: (i) if athletes train four times a week, BCAA supplementation may aid in recovery between training sessions due to the positive effects of BCAA at both less than 24 h and 24 h post-exercise.However, if they train only three times a week, supplementation is not suggested, (ii) supplementation of BCAA, both in low and high doses, for an extended period, could be an effective strategy for recovering from muscle damage induced by EIMD, (iii) and consuming BCAA before exercise or a training session has more beneficial effects on muscle damage biomarkers, as well as on muscle soreness.
