Effects of combined carbohydrate and protein supplementation on athletic performance and recovery of endurance runners：a double blind, random trial

Abstract Background The aim of this study is to explore the effects of ingesting protein supplementation before endurance exercise. Methods 10 recreationally active male runners (VO2max: 53.61±3.86 ml/kg•min) completed a run-to-exhaustion test three times. Each test involved 90 minutes of running at 70% VO2max, followed by a time to exhausted test for running at 80% VO2max. All subjects ingested three different, randomly assigned, supplement before the first phase. At the end of the first phase, CHO (carbohydrate) + CHO; PRO (protein) + CHO; CHO + PRO. Both carbohydrate and protein were supplemented at 0.4g•kg− 1BM− 1. Blood samples were obtained before, immediately after and 24 h after exercise for alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK), and myoglobin (MB). Results Three different supplement regimens did not cause a significant difference in exhaustion time (CHO + CHO: 432.36 ± 225.51s; PRO + CHO: 463.82 ± 227.45s; CHO + PRO: 461.45 ± 248.5s). However, ALT and AST in PRO + CHO were significantly lower than CHO + CHO 24h after exercise (ALT: 16.8 ± 6.31 VS. 24.39 ± 2.54 U/L; AST: 24.06 ± 4.77 VS. 31.51 ± 7.53 U/L, p < 0.05), and MB in PRO + CHO and CHO + PRO were significantly lower than CHO + CHO 24 h after exercise (40.71 ± 15.16; 38.12 ± 14.32; 64.32 ± 28.86 ng/mL, respectively, p < 0.05). Compared to CHO + CHO, CK in PRO + CHO increased less 24 h after exercise (404.22 ± 75.31 VS. 642.33 ± 68.57 U/L, p < 0.05). Conclusion Although combined carbohydrate and protein supplementation did not prolong exhaustion time, it can effectively relieve muscle damage, and it is better to supplement PRO before exercise.