Date of Completion
Ingestion of a protein and carbohydrate supplement after exercise may aide recovery, but its effect on markers of muscle damage remains unclear. The purpose of this study was to examine the effects of a protein-carbohydrate supplement ingested mid-workout on exercise-induced muscle damage (EIMD) as determined by blood levels of creatine kinase (CK), myoglobin and fast-twitch skeletal muscle troponin-I (sTnI). Eight competitive “Crossfit” men (age, 27.4 + 1.9 yrs; height, 180.4 + 2.4 cm; weight, 92.7 + 3.9 kg; body fat, 15.8 + 1.9 %; BMI 28.4 + 1.1) participated in a randomized, placebo-controlled, crossover study. Subjects performed two identical acute exercise trials (AET) separated by 7 days, during which they consumed a protein-carbohydrate supplement (28 g whey protein and 15 g carbohydrate) or a water control. AET consisted of a resistance exercise portion (5x5 front barbell squat, 80% 1RM, with 2 min rest), a 15 minute rest period where water or nutritional supplement was consumed, and an aerobic exercise portion (8X10sec maximal sprints, with 45sec rest). Serum measurements were obtained pre AET and immediately post, 30min post, 60min post, and 180min post AET. CK and myoglobin were analyzed using commercially available assays and sTnI was analyzed by SDS-PAGE under denaturing conditions. CK and myoglobin significantly increased over time indicating the AET induced EIMD (p<0.05), and sTnI was positively correlated with CK (r= 0.434; p<0.001). There was no significant difference between the supplement and water only trials. In conclusion a protein-carbohydrate supplement given mid-workout did not attenuate the initial elevation in blood levels of muscle damage after an acute bout of concurrent exercise.
Saenz, Catherine, "Effect of a Protein-Carbohydrate Beverage on Muscle Damage During an Acute Bout of Concurrent Exercise in Competitively-Training “Crossfit” Men" (2011). Master's Theses. Paper 134.