Abstract
The effectiveness of isometric conditioning activity (CA) is not well described in terms of the level of performance enhancement and the presence of a stretch and shortening cycle in subsequent explosive tasks. Therefore, the aim of this study was to evaluate the effect of a maximum isometric squat as the CA and a subsequent squat jump (SJ) and countermovement jump (CMJ) height.
A total of 31 semi-professional handball and soccer players were randomly assigned to two different conditions: (i) 3 sets of 3 repetitions (each lasting 3 s) of maximum isometric back squats (EXP), and (ii) no CA (CTRL). The jump height measurements were performed 5 min before the CA and approximately at the 4th and 8th minute following the completion of the CA.
Due to the high inter-individual variability in the potentiation responses, the best value obtained post-CA was also analyzed. The SJ height significantly increased from baseline to the 8th minute post-CA (p = 0.004; ES = 0.31; Delta = +3.1 +/- 5.0%) in the EXP condition.
On the other hand, the CMJ height was significantly higher in the 4th (p = 0.001; ES = 0.23; Delta = +2.7 +/- 3.7%) and 8th minute post-CA (p = 0.005; ES = 0.32; Delta = +3.6 +/- 5.7%) in comparison to baseline during the EXP condition. Furthermore, SJ height significantly increased from baseline to the best time-point during the EXP (p < 0.001; ES = 0.47; Delta = +4.9 +/- 4.9%) and CTRL (p = 0.038; ES = 0.21; Delta = +2.5 +/- 5.8%) condition.
Moreover, the CMJ height was significantly higher at the best time-points than at the baseline during EXP (p < 0.001; ES = 0.53; Delta = +5.6 +/- 4.7%) and CTRL (p = 0.002; ES = 0.38; Delta = +3.1 +/- 5.2%) condition. The findings from this study indicate that a maximum isometric squat, used as a CA, effectively improved SJ and CMJ height.
This suggests that the presence or absence of a stretch and shortening cycle in both CA and post-CA tasks does not significantly impact the post-activation performance enhancement response.