Effects of High-Speed Power Training on Muscle Performance and Braking Speed in Older Adults

We examined whether high-speed power training (HSPT) improved muscle performance and braking speed using a driving simulator. 72 older adults (22？m, 50？f; age = 70.6 ± 7.3？yrs) were randomized to HSPT at 40% one-repetition maximum (1RM) (HSPT: ？？ = 2 5 ; 3 sets of 12–14 repetitions), slow-speed strength training at 80%1RM (SSST: ？？ = 2 5 ; 3 sets of 8–10 repetitions), or control (CON: ？？ = 2 2 ; stretching) 3 times/week for 12 weeks. Leg press and knee extension peak power, peak power velocity, peak power force/torque, and braking speed were obtained at baseline and 12 weeks. HSPT increased peak power and peak power velocity across a range of external resistances (40–90%？1RM; ？？ < 0 . 0 5 ) and improved braking speed ( ？？ < 0 . 0 5 ). Work was similar between groups, but perceived exertion was lower in HSPT ( ？？ < 0 . 0 5 ). Thus, the less strenuous HSPT exerted a broader training effect and improved braking speed compared to SSST. 1. Introduction Resistance training is a commonly prescribed and broadly researched rehabilitative strategy for older adults to maintain or improve muscle strength and function. Resistance training interventions typically emphasize high-load, strengthening exercise; however, muscle power (force × velocity) has emerged as an important muscle performance characteristic in this population [1–7]. A key component of muscle power is the speed at which force is developed. Resistance training using high movement speeds and high external resistance [8] or high movement speeds and low external resistance [9–11] have demonstrated positive impact on both muscle power and some functional performance tests. A recent meta-analysis revealed that various forms of high-speed resistance training (i.e., power training) were more effective at improving muscle power with only a small impact on function compared to traditional slow-speed strength training [12]. In older adults, muscle power declines at up to twice the rate than muscle strength (3-4% versus 1-2%), mostly due to declines in velocity compared to force [13, 14]. Thus, interventions that potentially improve muscle power and the velocity component of power may be critical in this population, especially with regard to function. Different functional tasks, however, may require power with a greater velocity component or a greater force component depending on the nature of the specific task (e.g., moving the lower limb quickly to keep from falling versus slowly getting up from a chair); thus, different resistance training protocols may be able to deliver different aspects of power to