Relationships Between Changes In Performance And Body Composition Variables After A Ten-week Resistance Training Intervention

Abstract

Changes in body composition variables as well as strength and power performance are both apparent after resistance training interventions. PURPOSE: To compare multiple body composition variables and how they relate to changes in strength and power. METHODS: Eighteen trained men (25.8 ± 4.3y; 176.7 ± 5.0cm; 80.4 ± 12.0kg) completed a 10 week resistance training program. The first 8 weeks consisted of daily undulating periodized resistance training 3 days per week, focusing on either muscular hypertrophy, power, or strength. The final 2 weeks featured an overreach and taper phase. Tests consisted of 1RM strength of the bench press and leg press, a 30s Wingate, bench press peak power and velocity, and vertical jump height, peak power, and peak velocity. Body composition variables include total body and segmental Dual-Energy X-Ray Analysis (DXA), multi-frequency bioelectrical impedance (MFBIA), Single Frequency BIA (SFBIA), Bioimpedance Spectroscopy (BIS), Skinfold thicknesses, limb circumferences, and diagnostic ultrasound (US). RESULTS: With the exception of Wingate variables (p > 0.09), significant increases in strength and power were observed for all performance measurements (p < 0.01). Significant positive relationships were observed for MFBIA fat mass (FM) and MFBIA percent fat (%Fat) (r > 0.50, p < 0.03) for bench press velocity as well as for DXA trunk lean mass and leg press 1RM (r = 0.576, p = 0.012). Significant negative relationships were discovered for skinfold thicknesses of the suprailliac and vertical jump height (r = -0.507, p = 0.032) as well as US fat thickness and leg press 1RM (r = -0.711, p = 0.001). CONCLUSION: Changes in body composition variables (FM, FFM, %Fat, etc.) measured by different methods appear to produce varying relationships with performance variables after resistance training. An increase in fat measured by MFBIA appears to be associated with an increase in bench press velocity and an increase in trunk lean mass measured by DXA may predict an increase in leg strength. Also, a loss in subcutaneous hip (Skinfold) and thigh (US) fat may increase both vertical jump height and lower body strength, respectively. Thus, relationships between changes in body composition and performance after a resistance exercise intervention are dependent on both the method used as well as the variables being analyzed.