No Effect of Carbohydrate-Protein on Cycling Performance and Indices of Recovery.

PURPOSE:: The aim of this study was to determine whether adding protein to a carbohydrate beverage would improve late-exercise cycle time-trial performance over carbohydrate alone. Furthermore, we examined the effects of co-ingesting protein with carbohydrate during exercise on post-exercise markers of sarcolemmal disruption and the recovery of muscle function. METHODS:: In a double-blind, cross-over design, 12 trained male cyclists performed 120 min of steady-state cycling (SS) at ~55% V O2max followed by a time-trial lasting ~1 h (TT). At 15 min intervals during SS exercise participants consumed either a carbohydrate (CHO) or carbohydrate-protein (CHO+Pro) beverage (providing 65 g.h carbohydrate; or 65 g.h carbohydrate plus 19 g.h protein). Twenty-four hours following the onset of the SS cycle, participants completed a maximum isometric strength test. At rest and 24 h post-exercise, a visual analogue scale (VAS) was used to determine lower-limb muscle soreness, and blood samples were obtained for plasma creatine kinase (CK) concentration. Dietary control was implemented 24 h prior to, and during the time-course of each trial. RESULTS:: Average power output sustained during TT was similar for CHO and CHO+Pro with no effect of treatment on time-to-complete the time-trial (60:13 +/- 1:33 min:sec and 60:51 +/- 2:40 min:sec for CHO and CHO+Pro, respectively). Post-exercise isometric strength significantly declined for CHO (15 +/- 3%) and CHO+Pro (11 +/- 3%) compared to baseline (486 +/- 28 N). Plasma CK concentrations and VAS soreness significantly increased at 24 h post-exercise, with no difference between treatments. CONCLUSIONS:: The present findings suggest CHO+Pro co-ingestion during exercise does not improve late-exercise time-trial performance, ameliorate markers of sarcolemmal disruption or enhance the recovery of muscle function at 24 h post-exercise over carbohydrate alone.