Resistance training for explosive and maximal strength: effects on early and late rate of force development

Abstract

The aim of the present study was to verify whether strength training designed to improve explosive and maximal strength would influence rate of force development (RFD). Nine men participated in a 6-week knee extensors resistance training program and 9 matched subjects participated as controls. Throughout the training sessions, subjects were instructed to perform isometric knee extension as fast and forcefully as possible, achieving at least 90% maximal voluntary contraction as quickly as possible, hold it for 5 s, and relax. Fifteen seconds separated each repetition (6-10), and 2 min separated each set (3). Pre- and post-training measurements were maximal isometric knee extensor (MVC), RFD, and RFD relative to MVC (i.e., %MVC·s(-1)) in different time-epochs varying from 10 to 250 ms from the contraction onset. The MVC (Nm) increased by 19% (275.8 ± 64.9 vs. 329.8 ± 60.4, p < 0.001) after training. In addition, RFD (Nm·s(-1)) increased by 22-28% at time epochs up to 20 ms from the contraction onset (0-10 ms = 1679. 1 ± 597.1 vs. 2159.2 ± 475.2, p < 0.001; 0-20 ms = 1958.79 ± 640.3 vs. 2398.4 ± 479.6, p < 0. 01), with no changes verified in later time epochs. However, no training effects on RFD were found for the training group when RFD was normalized to MVC. No changes were found in the control group. In conclusion, very early and late RFD responded differently to a short period of resistance training for explosive and maximal strength. This time-specific RFD adaptation highlight that resistance training programs should consider the specific neuromuscular demands of each sport. Key PointsThe time-specific RFD adaptation evoked by resistance training highlight that the method of analyzing RFD is essential for the interpretation of results.Confirming previous data, maximal contractile RFD and maximal force can be differently influenced by resistance training. Thus, the resistance training programs should consider the specific neuromuscular demands of each sport.In active non-strength trained individuals, a short-term resistance training program designed to increase both explosive and maximal strength seems to reduce the adaptive response (i.e. increased RFDMAX) evoked by training with an intended ballistic effort (i.e. high-RFD contraction).

Keywords: Quadriceps; muscle adaptation; muscle strength; peak torque; power.

Figure 1.

Tests and training protocol timeline. # 48 hours interval. * 72 hours interval.

Figure 2(A-F).

Normalized moment-time curve, averaged for all subjects from the first (A) to sixth (F) week of training. For each subject, data obtained in all repetitions performed during the first weekly training session were collapsed. Dashed horizontal line corresponds to 90% of maximal voluntary contraction (MVC). Data are expressed as mean (solid line) ± SD (dashed line).

Figure 3.

Mean ± SD values of isometric peak torque (MVC) for trained group (TR) and control group (CON) before (Pre) and after (Post) the training period. *p ≤ 0.001 in relation to pre-test.

Figure 4.

Mean ± SD values of maximum rate of force development (RFD_MAX) and maximum relative rate of force development (RFDr_MAX) for trained group (TR) and control group (CON) before (Pre) and after (Post) the training period.

Figure 5(A-D).

Group mean ± SD values of rate of force development (RFD) and relative rate of force development (RFDr) in different times of contraction rise of isometric training (ISOM) and control (CON) groups obtained at pre- (black circles line) and post- (gray triangles line) training or daily activity periods, respectively. # p < 0.01; * p < 0.05 in relation to pre-test.