Effect of Time-of-Day-Specific Strength Training on Muscular Hypertrophy in Men

Abstract

The purpose of the present study was to examine effects of time-of-day-specific strength training on muscle hypertrophy and maximal strength in men. A training group underwent a 10-week preparatory training (wk 0-wk 10) scheduled between 17:00 and 19:00 hours. Thereafter, the subjects were randomized either to a morning or afternoon training group. They continued with a 10-week time-of-day-specific training (wk 11-wk 20) with training times between 07:00 and 09:00 hours and 17:00 and 19:00 hours in the morning group and afternoon groups, respectively. A control group did not train but was tested at all occasions. Quadriceps femoris (QF) cross-sectional areas (CSA) and volume were obtained by magnetic resonance imaging scan at week 10 and 20. Maximum voluntary isometric strength during unilateral knee extensions and half-squat 1 repetition maximum (1RM) were tested at week 0, 10, and 20 at a randomly given time of day between 09:00 and 16:00 hours. The QF average CSA and volume increased significantly (p < 0.001) in both the morning and afternoon training groups by 2.7% and 3.5%, respectively. The 0.8% difference between the training groups was not significant. The entire 20-week training period resulted in significant increases in maximum voluntary contraction and 1RM of similar magnitude in both training groups (p < 0.001 and p < 0.01, respectively) as compared with the control group. In conclusion, 10 weeks of strength training performed either in the morning or in the afternoon resulted in significant increases in QF muscle size. The magnitude of muscular hypertrophy did not statistically differ between the morning and afternoon training times. From a practical point of view, strength training in the morning and afternoon hours can be similarly efficient when aiming for muscle hypertrophy over a shorter period of time (<3 mo).

Effects of time of day on resistance exercise-induced anabolic signaling in skeletal muscle

“…To our best knowledge, the only study performed on humans found a tendency to smaller gains in muscle size when repeatedly training in the morning compared to the late afternoon hours (36). Although statistically insignificant, subjects training in the afternoon hours increased their m. quadriceps femoris volume, measured by magnetic resonance imaging, on average 30% more compared to their counterparts in the morning training group (36). One of the possible mechanisms contributing to the above-mentioned time-of-day-dependent training adaptations is signalling pathways involved in the control of protein synthesis and protein degradation.…”

“…Furthermore, early morning and late afternoon hours are also when hormonal signalling is dramatically different (e.g., cortisol to testosterone ratio -for a review see (16)). Considering the limited results from the acute studies (4) and from the long-term studies (36), it can be hypothesized that the time of day might influence the response to an acute bout of resistance exercise at the molecular level, e.g. hypertrophic signalling pathways.…”

The skeletal muscle circadian clock: current insights

“…83 Sedliak et al measured muscle volume to determine the effects of training-induced muscle hypertrophy at a specific time of day for 10 weeks in men. 84 The results showed that 10 weeks of training in the morning or in the evening increased the cross-sectional area of the quadriceps femoris muscle by 2.7% and 3.5%, respectively, but the difference was not significant. 84 Adaptation to training is temporally specific to increase muscle strength, but not muscle volume, in adult humans.…”

“…84 The results showed that 10 weeks of training in the morning or in the evening increased the cross-sectional area of the quadriceps femoris muscle by 2.7% and 3.5%, respectively, but the difference was not significant. 84 Adaptation to training is temporally specific to increase muscle strength, but not muscle volume, in adult humans. 83,84 Whether or not a specific time of training would improve sarcopenia in aged populations should be determined.…”

“…84 Adaptation to training is temporally specific to increase muscle strength, but not muscle volume, in adult humans. 83,84 Whether or not a specific time of training would improve sarcopenia in aged populations should be determined. The relevance of molecular clocks to a time-dependent effect of exercise also remains unknown.…”