Running Performance in Response to Different Forms of Carbohydrate Through Cephalic-Phase Responses

Carbohydrate ingestion during exercise enhances performance, albeit with potential gastrointestinal distress. Notably, ergogenic effects can arise without ingestion, likely mediated by cephalic-phase response, an anticipatory physiological response triggered by nutrient sensing. OBJECTIVE: To compare the effects of carbohydrate delivery via a carbohydrate mouth rinse (CMR) and carbohydrate dissolvable strip (DS) against a water mouth rinse (WMR) control on running performance during a 12.87-km time trial (TT). METHODS: Eighteen endurance-trained adults (16 men, 2 women) completed a randomized, controlled, crossover trial involving 3 TT sessions, each using a different treatment administered at the start and at every 1.61-km segment of the TT (8× total) on a motorized treadmill. RESULTS: The DS improved TT performance times and final completion time versus WMR (P = .02 and P = .03). There were no differences in performance time (P = .48) or final completion time (P = .08) for CMR versus WMR. Both DS and CMR led to a faster calculated pace per 1.61 km versus WMR (P < .001 and P = .01, respectively) and showed improvements in percent change in completion time (DS: -3.02 ± 0.01%, P = .01; CMR: -1.91 ± 0.01%, P = .04). The DS also increased average heart rate across the TT versus CMR and WMR (P = .01 for both) and percent change in heart rate versus WMR only (P = .02). There were no differences for ratings of perceived exertion. CONCLUSION: Both DS and CMR treatments improved markers of TT running performance versus WMR, but stronger evidence of improvement was observed for DS than for CMR.