Acute effects of combined isometric and plyometric conditioning activities on sports performance and tendon stiffness in female volleyball players

Abstract

This study aimed to compare the effects of bilateral and unilateral conditioning activities (CA; combined isometric and plyometric) on countermovement jump performance, modified t-agility test, Achilles tendon stiffness and skin surface temperature. Thirteen female semi-professional volleyball players performed two CAs in random order: 1) bilateral isometric half back squats followed by bilateral drop jumps (BI-CA); and 2) unilateral isometric half back squats followed by unilateral drop jumps (UNI-CA). To assess the effects of CAs, countermovement jump, modified t-agility test, Achilles tendon stiffness and skin surface temperature measurements were performed 5 min before and 6 min after the CA. Both CAs significantly increased thigh skin surface temperature from pre- to post-CA (BI-CA, p < 0.001; effect size [ES] = 1.41 and UNI-CA, p = 0.001; ES = 1.39) but none of them influenced modified t-agility test time (interaction: p = 0.338, main effect of time: p = 0.121 and condition: p = 0.819). The countermovement jump height and modified reactive strength index significantly increased from pre-to post-CA during the BI-CA condition (p = 0.003, ES = 0.45, and p = 0.008, ES = 0.48) but not for UNI-CA (p = 0.061, ES = 0.18 and p = 0.065, ES = 0.26). No significant impact has been found for countermovement depth (interaction: p = 0.054, main effect of time: 0.097, and condition: p = 0.41) as well as for contraction time (interaction: p = 0.536, main effect of time: p = 0.224, and condition: p = 0.807). Moreover, stronger and weaker limb CMJ relative peak force significantly decreased from pre-to post-CA (p = 0.014, ES = −0.31, and p = 0.027, ES = −0.26; respectively) during UNI-CA condition but not for BI-CA (p = 0.096, ES = 0.23, and p = 1.41, ES = 0.18). The stronger and weaker limb Achilles tendon stiffness significantly increased from pre-to post-CA during the UNI-CA condition (p = 0.013, ES = 0.60 and p < 0.001, ES = 0.79; respectively) but not for BI-CA (p = 0.66; ES = 0.15 and p = 0.265; ES = 0.42). Furthermore, the post-CA stronger limb Achilles tendon stiffness during the UNI-CA was significantly higher than that noted during the BI-CA (p = 0.006, ES = 0.7). The present study showed that combined isometric and plyometric bilateral CA effectively improved the countermovement jump but did not enhance the t-agility test performance. These findings indicate that exercise combinations could effectively produce a post-activation performance enhancement effect but should replicate the following explosive task as much as possible.

The effectiveness of isometric protocols using an external load or voluntary effort on jump height enhancement in trained females

“…Several authors have shown JH enhancement after voluntary isometric effort 19 , 34 , 44 , with Kalinowski et al 44 showing enhanced JH and Spieszny et al 19 demonstrating jump improvement among handball payers. Interestingly, peak performance showed wide variability, with some individuals peaking after four minutes and others peaking after eight.…”

The sex effects on changes in jump performance following an isometric back squat conditioning activity in trained adults

“…One of the most crucial factors for effective PAPE is appropriate intensity. Indeed, an effort of approximately 80%-RM is submaximal ( Seitz and Haff, 2016 ; Dobbs et al, 2019 ), though positive effects are observed with higher and lower loads ( Gołaś et al, 2017 ; Vargas-Molina et al, 2021 ) or by using voluntary contractions ( Kalinowski et al, 2022 ; Spieszny et al, 2022 ). In this regard, the intensity of the CA and rest intervals are also crucial ( Dobbs et al, 2019 ).…”

Postsubmaximal Isometric Full Squat Jump Potentiation in Trained Men

“…Their data are similar to the current study findings in relation to time to performance enhancement and intensity used. On the other hand, isometry can be combined with plyometric other activities, what increased jump performance effectively in female volleyball players ( 20 ). However, in contrast to the current study and that of Vargas-Molina et al ( 39 ), there was no relative external load, and subjects had to push on an immovable bar.…”