A multi-ingredient containing carbohydrate, proteins L-glutamine and L-carnitine attenuates fatigue perception with no effect on performance, muscle damage or immunity in soccer players

We investigated the effects of ingesting a multi-ingredient (53g carbohydrate, 14.5g whey protein, 5g glutamine, 1.5g L-carnitine-L-tartrate) supplement, carbohydrate only, or placebo on intermittent performance, perception of fatigue, immunity, and functional and metabolic markers of recovery. Sixteen amateur soccer players ingested their respective treatments before, during and after performing a 90-min intermittent repeated sprint test. Primary outcomes included time for a 90-min intermittent repeated sprint test (IRS) followed by eleven 15 m sprints. Measurements included creatine kinase, myoglobin, interleukine-6, Neutrophil; Lymphocytes and Monocyte before (pre), immediately after (post), 1h and 24h after exercise testing period. Overall, time for the IRS and 15 m sprints was not different between treatments. However, the perception of fatigue was attenuated (P<0.001) for the multi-ingredient (15.9±1.4) vs. placebo (17.8±1.4) but not for the carbohydrate (17.0±1.9) condition. Several changes in immune/inflammatory indices were noted as creatine kinase peaked at 24h while Interleukin-6 and myoglobin increased both immediately after and at 1h compared with baseline (P<0.05) for all three conditions. However, Myoglobin (P<0.05) was lower 1h post-exercise for the multi-ingredient (241.8±142.6 ng·ml-1) and CHO (265.4±187.8 ng·ml-1) vs. placebo (518.6±255.2 ng·ml-1). Carbohydrate also elicited lower neutrophil concentrations vs. multi-ingredient (3.9±1.5 109/L vs. 4.9±1.8 109/L, P = 0.016) and a reduced (P<0.05) monocytes count (0.36±0.09 109/L) compared to both multi-ingredient (0.42±0.09 109/L) and placebo (0.42±0.12 109/L). In conclusion, multi-ingredient and carbohydrate supplements did not improve intermittent performance, inflammatory or immune function. However, both treatments did attenuate serum myoglobin, while only carbohydrate blunted post-exercise leukocytosis.