Timing is Everything for Muscle Growth

Resistance exercise alters the post-exercise response of anabolic and catabolic hormones. A previous study indicated that the turnover of muscle protein in trained individuals is reduced due to alterations in endocrine factors caused by resistance training, and that muscle protein accumulation varies between trained and untrained individuals due to differences in the timing of protein and carbohydrate intake. We investigated the effect of the timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men. Subjects were 10 trained healthy men and 10 untrained healthy men. All subjects performed four sets of 8 to 10 repetitions of a resistance exercise (comprising bench press, shoulder press, triceps push-down, leg extension, leg press, leg curl, lat pulldown, rowing, and biceps curl) at 80% one-repetition maximum. After each resistance exercise session, subjects were randomly divided into two groups with respect to intake of protein (0.3 g/kg body weight) and carbohydrate (0.8 g/kg body weight) immediately after or 6 hours after the session. The protein supplement used in this study was a whey protein powder containing 78.4 g protein, 6.0 g lipid, and 8.4 g carbohydrate per 100 g product, as used in our previous studies. All subjects were on an experimental diet that met their individual total energy requirement.

The researchers assessed whole-body protein metabolism by measuring nitrogen balance at P0 and P6 on the last 3 days of exercise training. Nitrogen balance in the trained group was significantly higher at P0 than at P6, suggesting that muscle protein in these men was effectively accumulated in response to protein and carbohydrate supplementation if given immediately after exercise. In the study, the researchers observed no difference in nitrogen balance between the P0 and P6 conditions in the untrained group. The nitrogen balance in trained men was significantly higher at immediately after than at 6 hours after, whereas that in the untrained men was not significantly different between the two periods. The findings indicate that the post-exercise accumulation of muscle protein in the trained men who had continuously performed resistance exercise was higher compared with that of the untrained men. Furthermore, when protein and carbohydrate were consumed immediately after resistance exercise, the effect of protein intake on muscle protein accumulation was high in the trained men, but no effect was observed in the untrained men.

If you’re striving for maximal muscle growth, make sure to get your post-workout nutrition “immediately” post workout and not 6h later if you maximize protein synthesis. Basically, the study means that “advanced” trainers needs protein after exercise more than the untrained newbie.