The aim of this study was to compare the effects of 3 sets of isometric conditioning activity (ICA), each with an equal total duration (9 s per set) but with different distributions contractions, on force production during ICA and subsequent countermovement jump (CMJ) performance. Fifteen resistance-trained males participated in this study (age: 22.1 ± 2.4 years; body mass: 85.1 ± 9.7 kg; height: 181.3 ± 6.5 cm; relative one-repetition maximum (1RM) in back squat: 1.59 ± 0.32 kg/kg of body mass). Participants completed 3 conditions, each consisting of ICA in the half-back squat with a pushing isometric muscle action (PIMA) position at a 120-degree knee angle against an immovable barbell, differing in repetition distribution: 3 sets of 9 repetitions lasting 1 s each (SUST-1), 3 sets of 3 repetitions lasting 3 s each (SUST-3), 3 sets of single repetitions lasting 9 s (SUST-9), and a control condition (CTRL) without ICA. A 1-minute rest was allowed between sets. Approximately 3 min pre-ICA and at 15 s, 3-, 6-, 9-, and 12-minutes post-ICA, the CMJ performance was assessed. Moreover, peak force (PF) production, and force generated at 100 (Force100) and 200 ms (Force200) during each ICA were evaluated. A two-way repeated measures ANOVA indicated a main effect of time on CMJ height (F = 2.674; p = 0.029; ηp²=0.171) but did not show significant differences between conditions (F = 0.934; p = 0.434; ηp²=0.067) or interactions (F = 0.826; p = 0.648; ηp²=0.060). Post-hoc comparisons indicated a significant decrease in CMJ height at the 9th minute compared to the 3rd minute (35.7 ± 5.6 cm vs. 36.8 ± 5.5 cm post-CA; d = 0.161; p = 0.048). In addition, no significant interactions or main effects were found for CMJ contraction time, PF and Force100 during ICA. However, a main effect of condition was demonstrated on Force200 (F = 19.181; p < 0.001; ηp²= 0.013). Post-hoc comparisons revealed higher Force200 values in SUST-1 (mean difference [MD] = 549 ± 137 N; d = 1.049; p < 0.001) and SUST-3 (MD = 348 ± 112 N; d = 0.665; p = 0.002) compared to the SUST-9 condition. None of the ICAs used in the present study had any effect on the CMJ performance. However, the significantly higher Force200 values noted in the SUST-1, and SUST-3 conditions compared to the SUST-9 condition suggest that the specific distributions of isometric contraction influence the force generated during their execution.

Department of Sports Games Faculty of Physical Education and Sport Charles University Prague Czech Republic

Institute of Sport Sciences The Jerzy Kukuczka Academy of Physical Education Katowice Poland

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Kalinowski, R. et al. Acute effects of combined isometric and plyometric conditioning activities on sports performance and tendon stiffness in female volleyball participants. Front. Physiol.13, 1025839 (2022). PubMed PMC

Krzysztofik, M. et al. Acute effects of isometric conditioning activity on the viscoelastic properties of muscles and sprint and jumping performance in handball participants. J. Strength. Cond Res.37, 1486–1494 (2023). PubMed

Bogdanis, G. C., Tsoukos, A., Veligekas, P., Tsolakis, C. & Terzis, G. Effects of muscle action type with equal impulse of conditioning activity on postactivation potentiation. J. Strength. Cond Res.28, 2521–2528 (2014). PubMed

Blazevich, A. J. & Babault, N. Post-activation potentiation versus post-activation performance enhancement in humans: historical perspective, underlying mechanisms, and current issues. Front. Physiol.10, 1359 (2019). PubMed PMC

Boullosa, D. Post-activation performance enhancement strategies in sport: a brief review for practitioners. Hum. Mov.22, 101–109 (2021).

Damas, F. et al. Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling. Eur. J. Appl. Physiol.116, 49–56 (2016). PubMed

Magnusson, S. P. & Kjaer, M. The impact of loading, unloading, ageing and injury on the human tendon. J. Physiol.597, 1283–1298 (2019). PubMed PMC

Oranchuk, D. J., Storey, A. G., Nelson, A. R. & Cronin, J. B. Isometric training and long-term adaptations: effects of muscle length, intensity, and intent: A systematic review. Scand. J. Med. Sci. Sports. 29, 484–503 (2019). PubMed

Schaefer, L. V. & Bittmann, F. N. Are there two forms of isometric muscle action? Results of the experimental study support a distinction between a holding and a pushing isometric muscle function. BMC Sports Sci. Med. Rehabil. 9, 1–13 (2017). PubMed PMC

Noorkõiv, M., Nosaka, K. & Blazevich, A. J. Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production. J. Sports Sci.33, 1952–1961 (2015). PubMed

Balshaw, T., Massey, G. J., Maden-Wilkinson, T. M., Tillin, N. A. & Folland, J. P. Training-specific functional, neural, and hypertrophic adaptations to explosive- vs. sustained-contraction strength training. J. Appl. Physiol.120, 1364–1373 (2016). PubMed

Garbisu-Hualde, A., Gutierrez, L., Fernández-Peña, E. & Santos-Concejero, J. Intermittent voluntary isometric contractions effects on performance enhancement and sticking region kinematics in the bench press. J. Hum. Kinet. 87, 105 (2023). PubMed PMC

French, D. N., Kraemer, W. J. & Cooke, C. B. Changes in dynamic exercise performance following a sequence of preconditioning isometric muscle actions. J. Strength. Cond Res.17, 678–685 (2003). PubMed

Tsoukos, A., Bogdanis, G. C., Terzis, G. & Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J. Strength. Cond Res.30, 2250–2257 (2016). PubMed

Tillin, N. A. & Folland, J. P. Maximal and explosive strength training elicit distinct neuromuscular adaptations, specific to the training stimulus. Eur. J. Appl. Physiol.114, 365–374 (2014). PubMed

Spieszny, M. et al. Post-isometric back squat performance enhancement of squat and countermovement jump. Int. J. Environ. Res. Public. Health. 19, 12720 (2022). PubMed PMC

Lum, D. et al. Effects of two isometric strength training methods on jump and sprint performances: a randomized controlled trial. J. Sci. Sport Exerc.3, 115–124 (2021).

Gruber, M. et al. Differential effects of ballistic versus sensorimotor training on rate of force development and neural activation in humans. J. Strength. Cond Res.21, 274–282 (2007). PubMed

Tillin, N. A., Pain, M. T. G. & Folland, J. P. Short-term training for explosive strength causes neural and mechanical adaptations. Exp. Physiol.97, 630–641 (2012). PubMed

Kamimura, T. & Ikuta, Y. Evaluation of grip strength with a sustained maximal isometric contraction for 6 and 10 seconds. J. Rehabil Med.33, 225–229 (2001). PubMed

Dalton, B. et al. Central and peripheral neuromuscular fatigue following ramp and rapid maximal voluntary isometric contractions. Front. Physiol.15, 1434473 (2024). PubMed PMC

McKay, A. K. et al. Defining training and performance caliber: a participant classification framework. Int. J. Sports Physiol. Perform.17, 317–331 (2021). PubMed

Haff, G. G., Ruben, R. P., Lider, J., Twine, C. & Cormie, P. A comparison of methods for determining the rate of force development during isometric midthigh clean pulls. J. Strength. Cond Res.29, 386–395 (2015). PubMed

Comfort, P. et al. Normalization of early isometric force production as a percentage of peak force during multijoint isometric assessment. Int. J. Sports Physiol. Perform.15, 478–482 (2019). PubMed

Lum, D., Comfort, P., Barbosa, T. M. & Balasekaran, G. Comparing the effects of plyometric and isometric strength training on dynamic and isometric force-time characteristics. Biol. Sport. 39, 189 (2022). PubMed PMC

Heishman, A. D. et al. Countermovement jump reliability performed with and without an arm swing in NCAA division 1 intercollegiate basketball participants. J. Strength. Cond Res.34, 546–558 (2020). PubMed

Cohen, J. Statistical Power Analysis for the Behavioral Sciences (Electronic). Burlington, MA: Elsevier Science (2013).

Boullosa, D. et al. A new taxonomy for postactivation potentiation in sport. Int. J. Sports Physiol. Perform.15, 1197–1200 (2020). PubMed

Docherty, D. & Hodgson, M. J. The application of postactivation potentiation to elite sport. Int. J. Sports Physiol. Perform.2, 439–444 (2007). PubMed

Xenofondos, A., Bassa, E., Vrabas, I. S., Kotzamanidis, C. & Patikas, D. A. Muscle twitch torque during two different in volume isometric exercise protocols: fatigue effects on postactivation potentiation. J. Strength. Cond Res.32, 578–586 (2018). PubMed

Skurvydas, A. et al. What are the best isometric exercises of muscle potentiation? Eur. J. Appl. Physiol.119, 1029–1039 (2019). PubMed

Lum, D., Ong, K. Y. & Haischer, M. H. Postactivation performance enhancement with maximal isometric contraction on Power-Clean performance across multiple sets. Int. J. Sports Physiol. Perform.19, 265–270 (2023). PubMed

Buckthorpe, M., Erskine, R. M., Fletcher, G. & Folland, J. P. Task-specific neural adaptations to isoinertial resistance training. Scand. J. Med. Sci. Sports. 25, 640–649 (2015). PubMed