Assessment of the loaded squat jump and countermovement jump exercises with a linear velocity transducer: which velocity variable provides the highest reliability?

ABSTRACT

This study aimed to compare the between-session reliability of three typically measured velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and maximum velocity [Vmax]) to assess vertical jump performance. Totally, 23 men had their squat jump (SJ) and countermovement jump (CMJ) tested against five different loading conditions (17, 30, 45, 60 and 75 kg) during two consecutive weeks. The two sessions of each jump type were performed within the same week separated by 48–72 h. The main finding was a significant difference in reliability between the variables, which were ranked from the highest to the lowest reliable as follows (median coefficient of variation [CV] and range): Vmax (CV = 2.35% [1.85%–3.23%]) >MV (CV = 3.29% [2.18%–4.40%]) >MPV (CV = 3.69% [2.08%–5.17%]). A significant variable × exercise interaction was also observed showing that the differences in reliability between the variables were meaningful during the SJ (MV: CV = 3.93% [3.06%–4.40%], MPV: CV = 4.61% [4.07%–5.17%], and Vmax: CV = 2.14% [1.85%–2.71%]), while no significant differences were observed for the CMJ (MV: CV = 2.43% [2.18%–3.70%], MPV: CV = 2.71% [2.08%–3.63%], and Vmax: CV = 2.40% [1.97%–3.23%]). These results suggest that the Vmax should be the recommended variable for obtaining a reproducible measure of lower-body ballistic performance, especially during the SJ exercise.

KEYWORDS:

• Vertical jump
• mean velocity
• mean propulsive velocity
• maximum velocity
• linear position transducer

Acknowledgments

We would like to thank all the participants who selflessly participated in the study. This study is part of a PhD Thesis conducted in the Biomedicine Doctoral Studies of the University of Granada, Spain.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Spanish Ministry of Education, Culture and Sport under a pre-doctoral grant (FPU15/03649) awarded to APC and by the University of Granada under a postdoctoral grant (perfeccionamiento de doctores) awarded to AGR.