Single-versus multi-joint isometric protocols to induce a post-activation potentiation effect on squat jump performance

Purpose. The objective of the study was to analyse the effects of post-activation potentiation induced by single- and multijoint maximal voluntary isometric contractions (MVIC) on squat jump performance. Methods. Overall, 13 resistance-training males volunteered to participate in the study. Isometric knee extension exercise was chosen to represent single-joint MVIC (MVIC-SJ) and isometric squat to represent multi-joint MVIC (MVIC-MJ). Four experimental protocols were implemented in a randomized order on different days as follows: P1: Squat jump performed before and 3 minutes after MVIC-MJ; P2: Squat jump performed before and 7 minutes after MVIC-MJ; P3: Squat jump performed before and 3 minutes after MVIC-SJ; P4: Squat jump performed before and 7 minutes after MVIC-SJ. Jump height, mean power output, peak power output, net impulse, and electromyographic activity of lower limbs were analysed in squat jump before and after the interventions. Results. ANOVA showed that peak power output increased in P1 (p = 0.04). No difference was found for electromyographic activity in any of the protocols. Conclusions. We concluded that MVIC-MJ performed 3 minutes before the main task (P1) was more effective than MVIC-SJ in optimizing squat jump performance and that the changes in performance were unrelated to muscle activation. © 2020 University School of Physical Education in Wroclaw.