Effects of Soy Protein Bar Supplement Combined with Resistance Training on Strength and Exercise Performance

Abstract

Resistance training has been widely used for increasing muscle strength, muscle hypertrophy, rate of force development (RFD), and muscular endurance. Protein supplements are frequently consumed by athletes and recreationally active adults to achieve greater gains in muscle mass and strength and improve exercise performance. PURPOSE: This study was to investigate the effects of soy protein bar consumption on body composition, strength, skill-related fitness and exercise performance when given following 2 weeks of resistance training in student athletes. METHODS: 20 college-aged, health males (age 20.6 ± 1.4 yr) were recruited for this study. Subjects were randomly and equally divided into two groups, either consuming soy protein bar (SOY protein group, 20 g protein/day) or maintaining their daily food intake (Control group) on training days. Subjects trained 3 days per week for 2 weeks on a resistance-training program (including squat, biceps curl, triceps extension, leg extension, leg curl). The soy protein bars were consumed immediately following exercise. Body composition, upper and lower body strength, skill-related fitness, and exercise performance were measured before and after study. RESULTS: Compared to control group, the changes of 1-RM leg curl (+7.78 ± 6.2 vs. +1.25 ± 5.2 kg, p=0.023) and arm curl (+3.50 ± 2.1 vs. +0.94 ± 2.7 kg, p=0.033), power (standing long jump: +12.5 ± 9.4 vs. +3.80 ± 5.5 cm, p=0.021) and push up: +4.4 ± 4.3 vs. +0.6 ± 3.0 times, p=0.036), agility (side step: +1.78 ± 1.0 vs. +0.50 ± 0.8 times, p=0.007), and time to exhaustion (+61.8 ± 31.3 vs. +14.2 ± 59.5 seconds, p=0.050) were significantly improved in SOY protein group. However, no detectable differences were present in body composition. CONCLUSION: Findings from this study showed that the post-exercise consumption of soy protein bar consumption could improve muscle strength, skill-related fitness, and exercise performance in student athletes.