Effectiveness of whey protein supplements on the serum levels of amino acid, creatinine kinase and myoglobin of athletes: a systematic review and meta-analysis

BACKGROUND: Consuming whey protein supplements, along with physiotherapy and psychotherapy, have been recognised in sports performance. Whey protein supplements (WPS) is one of the commonly used supplements as ergogenic aids for athletes to enhance their muscle performance and recovery during sport-related injuries. The purpose of this systematic review is to investigate the effectiveness of WPS over the blood biochemistry mainly amino acids, creatinine kinase and myoglobin which influence performance and recovery among athletes. METHOD: A comprehensive literature search was conducted to identify randomised control trials (RCTs) and non-RCTs that investigated the effectiveness of WPS on amino acids, creatinine kinase and myoglobin among athletes. Risk of Bias in Non-Randomised Studies of Interventions tool (ROBINS-I) and Cochrane Risk of Bias Assessment tool were used to rule out the quality of studies. Meta-analysis was performed using a random effect model with STATA version 14.2. The weighted mean difference was used to estimate the effectiveness of WPS against other supplements. RESULTS: A total of 333,257 research articles were identified; of these, 15 records were included to proceed with the analysis. Meta-analysis has shown that WPS has significantly overall increased the level of essential amino acids level by 624.03 nmol/L (CI = 169.27, 1078.8; I(2) = 100%; p = 0.00) and branched-chain amino acids level by 458.57 nmol/L (CI = 179.96, 737.18; I(2) = 100%; p = 0.00) compared to the control group (without WPS). Moreover, was observed to decrease myoglobin level by 11.74 ng/ml (CI = − 30.24, 6.76; I(2) = 79.6%; p = 0.007) and creatine kinase level by 47.05 U/L (CI = − 129.47, 35.37; I(2) = 98.4%; p = 0.000) compared to the control group. CONCLUSION: The findings revealed that the clinical evidence supports the effectiveness of WPS as a positive ergogenic aid on athletes’ amino acids, creatinine kinase and myoglobin. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13643-019-1039-z) contains supplementary material, which is available to authorized users.