Association Between Reactive Strength Index and Metabolic Cost of Running in Male Master Athletes.

Abstract

Purpose: To examine the association between reactive strength index (RSI) and metabolic cost of running (MCr) in master athletes. We hypothesized that individuals with a higher RSI would exhibit a lower MCr, that both variables would be associated, and that age would moderate this relationship.

Methods: Forty-five male master athletes participated to this study. A median split was performed to constitute 2 age groups (group 1, 47.7 [1.7] y old; group 2, 56.3 [4.6] y old). Participants underwent a single 45-minute session during which RSI was assessed with drop jumps, and MCr, during a continuous exercise of submaximal intensity performed on a treadmill.

Results: A small negative association was found between net MCr and RSI in the overall sample (RSI mean r = -.38, P < .05; RSI max r = -.38, P < .05). Group 1 exhibited a lower net MCr (P < .01, d = -0.84) and higher RSI (P < .01, d > 0.82) than group 2. However, the association between the 2 measures was verified specifically in group 2 (RSI from a 20-cm drop jump, r = -.53, P < .01; RSI mean, r = -.50, P < .05; RSI maximum, r = -.57, P < .01).

Conclusions: RSI is associated with net MCR in master athletes, particularly in older participants. Additional intervention studies are now required to further explore this association.