If you do strength training because you want to build muscle, then working out early in the evening is a better time than in the morning. We’ve posted links to studies that have shown this at the bottom of the page. And if you combine strength training with cardio training, early evening workouts also result in more muscle growth than morning workouts, report Finnish sports scientists in Applied Physiology, Nutrition and Metabolism.
The researchers did an experiment with 42 male students, none of whom had done strength or endurance training in the past year. Most of the students had to train 2-5 times a week for a period of 24 weeks, doing both strength training and cardio training sessions. Ten participants did not train and functioned as the control group.
The researchers divided the other 32 participants into 4 groups.
mE+S Participants trained between 6.30 and 10.00 hrs. They started with cardio training and then did their resistance training.
mS+E Participants trained between 6.30 and 10.00 hrs. They started with strength training and then did their cardio training.
eE+S Participants trained between 16.30 and 20.00 hrs. They started with cardio training and then did their strength training.
eS+E Participants trained between 16.30 and 20.00 hrs. They started with resistance training and then did their cardio training.
The figure below shows the increase in the vastus lateralis muscle that the researchers observed on scans. The participants who trained in the evenings built up more muscle mass than the participants who trained in the mornings. The order in which they did the two different types of workout made no difference. [That may be because the participants were untrained. Many studies with trained participants show that cardio training reduces the effects of strength training considerably.]
The eE+S group built up more muscle mass than the eS+E group, but the difference was not statistically significant.
The researchers also measured the participants’ endurance capacity, and again working out later in the day turned out to be most effective – as long as the participants started with the cardio training and did the strength workout afterwards.
The effect of the timing of training is subtle, the researchers stress. The effects only become visible after training for about three months.
Effects of morning versus evening combined strength and endurance training on physical performance, muscle hypertrophy, and serum hormone concentrations
This study investigated the effects of 24 weeks of morning versus evening same-session combined strength (S) and endurance (E) training on physical performance, muscle hypertrophy, and resting serum testosterone and cortisol diurnal concentrations. Forty-two young men were matched and assigned to a morning (m) or evening (e) E + S or S + E group (mE + S, n = 9; mS + E, n = 9; eE + S, n = 12; and eS + E, n = 12). Participants were tested for dynamic leg press 1-repetition maximum (1RM) and time to exhaustion (Texh) during an incremental cycle ergometer test both in the morning and evening, cross-sectional area (CSA) of vastus lateralis and diurnal serum testosterone and cortisol concentrations (0730 h; 0930 h; 1630 h; 1830 h). All groups similarly increased 1RM in the morning (14%–19%; p < 0.001) and evening (18%–24%; p < 0.001). CSA increased in all groups by week 24 (12%–20%, p < 0.01); however, during the training weeks 13–24 the evening groups gained more muscle mass (time-of-day main effect; p < 0.05). Texh increased in all groups in the morning (16%–28%; p < 0.01) and evening (18%–27%; p < 0.001), however, a main effect for the exercise order, in favor of E + S, was observed on both testing times (p < 0.051). Diurnal rhythms in testosterone and cortisol remained statistically unaltered by the training order or time. The present results indicate that combined strength and endurance training in the evening may lead to larger gains in muscle mass, while the E + S training order might be more beneficial for endurance performance development. However, training order and time seem to influence the magnitude of adaptations only when the training period exceeded 12 weeks.