Rate Of Force And Acceleration Improvement In Males Performing Bilateral Three-Dimensional Isotonic Concentric Curls

Numerous athletic settings involve multidimensional isotonic force output. The rates of improvement in power and acceleration upon initiating a 3D isotonic training program are not well known. PURPOSE: To assess increases in power and acceleration of the biceps brachii among males performing novel 3D isotonic exercise. METHODS: We measured 40 males across the lifespan initiating exercise on a Proteus device, which produces 3D concentric loads via electromagnetic resistance. Each subject completed a minimum of 5 exercise sessions on separate days involving bilateral bicep curls. After 8 sessions, 23 subjects were retained. We captured peak power achieved in each repetition, and we exported average peak power across all repetitions (mean power) as well as the highest power achieved in any repetition (peak power). We also exported mean and peak acceleration. Repeated measures ANOVA tested differences in performance metrics across days 1, 5, and 8 (n = 23). Paired-samples t-tests measured differences between sessions 1 and 5 (n = 40). Linear regressions tested the effect of session number on power and acceleration holding age constant. RESULTS: Subject age was 35.1 ± 21.3 yr, height was 69.6 ± 3.8 in, and weight was 176.8 ± 35 lb. During the initial session, mean power was 107.8 ± 63.0 W, peak power was 121.8 ± 68.4 W, mean acceleration was 6.7 ± 5.0 m/s2, and peak acceleration was 8.6 ± 5.8 m/s2. Comparing sessions 1 to 5, mean power increased to 162.6 ± 122.9 W (p < 0.001), peak power increased to 184.2 ± 145.6 W (p < 0.001), mean acceleration increased to 10.3 ± 8.7 m/s2 (p = 0.002), and peak acceleration increased to 28.5 ± 92.8 m/s2 (p = 0.089). Improvements in mean and peak power were both significant between sessions 1 and 5 (p < 0.001), but not between sessions 5 and 8 (p > 0.250). Improvements in mean acceleration were significant between sessions 1 and 5 (p = 0.002), but not between sessions 5 and 8 (p = 1.000). Holding age constant, linear regression on days 1 through 5 found each additional exercise session to predict an improvement of 11.0 W mean power (p = 0.001), 12.4 W peak power (p < 0.001), and 0.9 m/s2 mean acceleration (p = 0.011). CONCLUSION: Men across the lifespan experienced rapid increases in force and acceleration of the biceps brachii upon initiating bilateral 3D concentric exercise. Rapidity of improvement tapered after 5 sessions.