A new study published in the Journal of Physiological Anthropology investigated the impact protein and carbohydrate (CHO) intake timing following resistance training on nitrogen balance among trained and untrained men. Ten trained men (mean age, 23?±?4 years) and ten untrained men (mean age, 23?±?1 years) took part in the investigation. All of the subjects repeatedly performed a resistance training bout consisting of bench press, shoulder press, triceps push-down, leg extension, leg press, leg curl, lat pull-down, cable row, and biceps curl exercises. Each lift was performed for four sets of 8-10 repetitions at 80% of their measured 1RM.
The weightlifting bout was performed several times on separate days by each subject. After each session, the men were randomly divided into two groups with respect to intake of protein (0.3 g/kg BW) and CHO (0.8 g/kg BW) immediately after or six (6) hours after the session. All of the subjects were on an experimental diet that met their individual total energy requirement. The research team assessed whole-body protein metabolism by measuring nitrogen balance immediately following and six (6) hours after each session. The results showed that nitrogen balance was significantly lower among the trained men when compared to the untrained men with protein-CHO intake immediately after and six (6) hours after the workout. Nitrogen balance among the trained men was relatively improved when given the protein-CHO meal immediately after their session, while among the untrained men there was no significant difference between the two periods.
The investigators concluded that the timing of protein and CHO intake after resistance exercise influences nitrogen balance differently among trained and untrained young men. In this study, this relationship may have presented itself due to the higher relative 80% 1RM intensities presumably performed among the trained men. This would create greater metabolic and muscle cell distress; thereby warranting more immediate nutritional support for optimized recovery and nitrogen balance.