Effects of a dietary milk or carbohydrate supplement with resistance training on body composition, muscle strength and anabolic hormones in untrained men

Twenty untrained men (18-25 y) were assigned to consume either a milk supplement (MILK) or a carbohydrate-electrolyte supplement (CHO) immediately following each resistance workout during a 10 wk resistance training program. Subjects trained 3 d/wk beginning with an intensity of 55% 1-RM and progressing to 97% 1-RM by wk 10. Muscle strength (1-RM), body composition (DEXA) and resting, fasted serum concentrations of total and free testosterone and IGF-1 were measured pre- and post-training. CHO tended to reduce, while MILK increased body weight (P = 0.10). All subjects significantly reduced percent body fat (1.1%) and significantly increased lean body mass (1.21 kg) as a result of the resistance training with no significant differences between treatments. However, MILK tended to increase lean body mass (P = 0.1) more than CHO (1.6 and 0.8 kg, respectively). About 39% of lean mass gain for all subjects was in the leg region, while the arms accounted for about 28% of lean gain. Resistance training also caused a similar significant 44% increase in muscle strength for the seven exercises combined for both groups. Resting total and free testosterone concentrations significantly decreased from baseline values in both groups of subjects (16.7% and 11%, respectively), while resting insulin concentrations significantly increased in all subjects (P<0.01). There were no significant changes in resting, fasted IGF-1 concentrations. In summary, dietary supplementation with a MILK or CHO beverage immediately following resistance exercise resulted in similar changes in muscle strength and hormone concentrations following a 10 wk periodized resistance training program. MILK tended to increase body weight and lean body mass more so than CHO.