Dissociated Time Course of Recovery Between Strength and Power After Isoinertial Resistance Loading in Rugby Union...

Kennedy, RA and Drake, D. Dissociated time course of recovery between strength and power after isoinertial resistance loading in rugby union players. J Strength Cond Res 32(3): 748-755, 2018-There is a substantial amount of research on the responses to isometric and eccentric loading. However, only a paucity of literature exists on the responses to isoinertial loading, especially in trained athletic populations using realistic loading protocols. The purpose of this study was to examine the acute neuromuscular response to a bout of isoinertial resistance loading in elite rugby players. Seventeen male (age: 19.5 ± 2.3 years) rugby union players performed a conventional maximal isoinertial resistance loading protocol. Countermovement jump (CMJ) and maximal voluntary isometric contraction (MVC) squat performance were measured on 3 occasions: at baseline, immediately post, and 48 hour post. The results indicated that the decrease in MVC (9.7%) is greater than or comparable with the CMJ output variables (4.2-10.3%), immediately postexercise. Although isometric strength had demonstrated a full recovery at 48 hour post, many of the key CMJ output variables were still impaired (p ≤ 0.05). Similar findings were observed in the normalized CMJ curves. Complete recovery of the ability to rapidly produced force may require more than 48 hours in many athletes. Individual responses should, therefore, be monitored to help plan acute and chronic training loads. It is recommended that future fatigue studies should incorporate temporal phase analyses to consider the power-, force-, velocity-, and displacement-time curves.