Impact of Time Restricted Feeding on Muscular Strength Within a Healthy Adult Population.

Abstract

Time restricted feeding (TRF) is a feeding habit that restricts the amount of time during the day in which individuals consume calories. TRF has been shown to produce several health benefits, one of which may be an increase in force production. Muscular strength and nutritional intake have been strongly researched prior to this study. Though little research exists investigating the impacts of TRF on muscular strength in human subjects. PURPOSE: The purpose of this study was to identify the potential impacts of TRF on muscular strength. METHODS: Participants participated in two, four-week periods during which caloric intake, sleep duration, sleep quality, exercise, and medications were all documented. The first period, participants partook in non-TRF eating behavior. The second period participants were exposed to a nine-hour window of TRF. To measure muscular strength, participants were tested using an isokinetic dynamometer. Resting metabolism was also measured. Statistical analyses quantifying within subject effects were performed with a repeated measures ANOVA. Post-hoc analyses were performed to elicit differences between testing periods. RESULTS: Both mean torque flexion at 60 degrees/second (MTF 60) (83.92 Nm ± 29.53Nm vs. 95.63 Nm ± 28.95 Nm) and mean torque flexion at 180 degrees/second (MTF 180) (66.75 Nm ± 25.9 Nm vs. 69.01 Nm ± 21.29 Nm vs. 75.55 Nm ± 23.9 Nm; F = 7.920 Nm) had a significant increase from pre-test to TRF, as well as non-TRF to TRF. Post-hoc testing revealed significant differences between pre-test and TRF MTF 60 increased (p-value=0.001). Similar results were found for MTF 180 as well (p-value=0.037). When observing respiratory quotient (RQ) at rest (0.716±0.077 vs. 0.73 ±0.077 vs. 0.08±0.79; F = 8.352) there was a significant increase from pre-test to TRF (p-value=0.008), as well as non-TRF to TRF (p-value=0.034). Lastly, after analyzing total strength training days from non-TRF to TRF (8.11 days ± 1.18 vs. 5.22 days ± 1.48), a significant decrease was found (p-value=0.003). CONCLUSION: Post TRF, participants showed an increase in muscular strength and resting RQ despite a decrease in strength training. Increased glucose utilization may be linked to short bouts of increased muscular strength activity. Future studies are needed to identify physiological mechanisms behind these findings.