Effects of food bar chewing duration on the physiologic, metabolic, and perceptual responses to moderate-intensity running

Chewing duration can affect food particle size, gastric processing, and postprandial glycemia, but these effects have not been investigated with exercise. This study examined how the chewing duration of a food bar impacts glycemic and metabolic responses, gastrointestinal (GI) symptoms, psychological affect, and performance during endurance running.

This randomized, unblinded, crossover study had 15 males (35.2 ± 7.4 years, VO_2peak: 56.1 ± 5.2 ml/kg/min) attend three laboratory visits. Visit 1 required a VO_2peak test, 10 min familiarization run at 60% VO_2peak, and familiarization time-to-exhaustion (TTE) test (10 min at 90% VO_2peak, followed by TTE at 100% VO_2peak). Visits 2 and 3 consisted of a 60 min run at 60% VO_2peak, followed by TTE testing. Participants were fed 45 g of a bar (180 kcal, 4 g fat, 33 g carbohydrate, 3 g protein, 1 g fiber) in 9 g servings 30 min before running, and 27 g of bar in 9 g servings at three timepoints during the 60 min run. Participants consumed the servings in 20 (20CHEW) or 40 (40CHEW) masticatory cycles, at 1 chew/second. Outcomes included blood glucose, substrate use, GI symptoms, perceived exertion (RPE), overall feeling, and TTE.

Post-prandial blood glucose, GI symptoms, and RPE increased over time, but there were no significant between-condition or condition-by-time effects. TTE showed no significant between-condition effect (20CHEW: 288 ± 133 s; 40CHEW: 335 ± 299 s; p = 0.240). Overall feeling demonstrated a time-by-condition effect (p = 0.006), suggesting possible better maintenance over time with 40CHEW.

Cumulatively, the results suggest that extended chewing minimally impacts physiology, perceptions, and performance during 60 min moderate-intensity running.