The effects of periodized resistance training on the neuromuscular performance, body composition and balance control among older and young adults

Strength, power and muscle mass decline with age. These declines lead to poorer balance and increased risk for falls. Intervention studies using a periodized resistance training (RT) among the older are limited, despite its widespread applications in fitness and sports among young adults. In addition, the effects of periodized RT on balance control remain to be investigated. This study sought to examine the effects of a short term periodized RT on the neuromuscular performance, body composition and balance control among older and young adults. A total of 31 untrained older (n=14, 8M & 6F; 69 ± 2 years) and young adult volunteers (n=17, 4M & 13F; 25 ± 3 years) completed 14-weeks of traditional periodized RT that included mesocycles targeted for hypertrophy, maximal strength, power and explosiveness. Measurements were conducted at two time-points: before and after RT. Neuromuscular performance tests included isometric unilateral plantar flexion (PF), isometric knee extension (KE), countermovement jump (CMJ) and one-repetition maximum (1RM) leg press. Electromyography (EMG) data was collected on all neuromuscular performance tests. In addition, body composition was measured using dual energy absorptiometry (DXA). Finally, center of pressure (COP) disturbance was assessed using a force platform for static balance, and an antero-posteriorly translating perturbation device for dynamic balance. Neuromuscular performance results showed that both older and young adult groups increased KE maximal voluntary isometric contraction (MVIC) (both at p<0.001), 1RM leg press (both at p<0.001), and CMJ (p<0.01 & p<0.001 respectively). Only the young adults increased PF MVIC (p<0.001), PF rate of torque development (RTD) (p<0.05) and CMJ peak power (p<0.01), whereas both did not undergo a change in KE RTD. Body composition data revealed that only the older increased body mass (p<0.05), while only the young adults increased total lean mass (p<0.05) and total fat free mass (p<0.01). Static balance remained unchanged in both groups. Dynamic balance findings revealed that both older and young adult groups decreased COP disturbance during low intensity-anterior (Ant) (p<0.01) and averaged (Ave) posterior (Post) (p<0.05 & p<0.01) perturbations respectively. In addition, only the older decreased COP disturbance from high-Post perturbations (p<0.05), while only the young adults decreased from low Post (p<0.05), mid Ant (p<0.001) and Ave Ant (p<0.001) perturbations. Moreover, an age-related difference was revealed for CMJ height (p<0.05) and Ave Ant COP (p