Plyometric Exercise Transiently Enhances Twitch Torque but Fails to Enhance the Rate of Force Development Evaluated Using the Isometric Midthigh Pull.

The effects of jump exercises as a conditioning activity (CA) on the rate of force development (RFD) measured during the isometric midthigh pull (IMTP) have not been investigated. Therefore, we aimed to investigate the effect of the CA comprising three sets of five countermovement jumps on the RFD measured during the IMTP, and furthermore to investigate whether post-activity potentiation (PAP) would be involved in this mechanism. Thirteen healthy male university students (age: 19.7 ± 0.6 years; training experience: 3.0 ± 1.4 years) participated in five sessions. Initially, the twitch torque was elicited by electrical stimulation after the CA to investigate whether PAP was elicited. Participants then completed the following four sessions: experimental condition sessions, in which the IMTP was performed 1 or 4 min after the CA, and control condition sessions, in which the IMTP was performed 7 or 10 min after the pre-measurement because the experimental condition included a 2-min rest interval before the CA and approximately 4 min were required to perform the CA. One-way analysis of variance (ANOVA) with Bonferroni post-hoc adjustments revealed the presence of PAP 1 and 2 min after the CA. Two-way ANOVA revealed significant interaction effects for the 0-200 ms and 0-250 ms RFD at the 1st min, and the 0-150 ms and 0-250 ms RFD at the 4th min after the CA. However, the Bonferroni post-hoc test failed to detect any significant increase in the RFD index under the experimental conditions. The CA with jump exercises induced PAP up to 2 min after the CA implementation, but failed to significantly increase the RFD measured by the IMTP.