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

BREEN, L., K. D. TIPTON, and A. E. JEUKENDRUP. No Effect of Carbohydrate-Protein on Cycling Performance and Indices of Recovery. Med. Sci. Sports Exerc., Vol. 42, No. 6, pp. 1140-1148, 2010. Purpose: The aim of this study was to determine whether adding protein to a CHO beverage would improve late-exercise cycle time-trial performance over CHO alone. Furthermore, we examined the effects of coingesting protein with CHO during exercise on postexercise markers of sarcolemmal disruption and the recovery of muscle function. Methods: In a double-blind, crossover design, 12 trained male cyclists performed 120 min of steady-state (SS) cycling at approximately 55% (V)over dotO(2max) followed by a time trial lasting approximately 1 h. At 15-min intervals during SS exercise, participants consumed either a CHO or a CHO + protein (CHO + Pro) beverage (providing 65 g.h(-1) CHO or 65 g.h(-1) CHO plus 19 g.h(-1) protein). Twenty-four hours after the onset of the SS cycle, participants completed a maximum isometric strength test. At rest and 24 h postexercise, a visual analog scale was used to determine lower-limb muscle soreness, and blood samples were obtained for plasma creatine kinase concentration. Dietary control was implemented 24 h before and during the time course of each trial. Results: Average power output sustained during time trial was similar for CHO and CHO + Pro, with no effect of treatment on the time to complete the time trial (60: 13 +/- 1: 33 and 60: 51 +/- 2: 40 (min:s) for CHO and CHO + Pro, respectively). Postexercise isometric strength significantly declined for CHO (15% +/- 3%) and CHO + Pro (11% +/- 3%) compared with baseline (486 +/- 28 N). Plasma creatine kinase concentrations, and visual analog scale soreness significantly increased at 24 h postexercise, with no difference between treatments. Conclusions: The present findings suggest that CHO + Pro coingestion 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 postexercise over CHO alone.