ABSTRACT
It is unclear if increases in 1 repetition maximum (1RM) in quarter squats result in higher gains compared with full depth squats in isometric force production and vertical jump performance. The aim of the research projects was to compare the effects of different squat variants on the development of 1RM and their transfer effects to Countermovement jump (CMJ) and squat jump (SJ) height, maximal voluntary contraction (MVC), and maximal rate of force development (MRFD). Twenty-three women and 36 men (mean age: 24.11 ± 2.88 years) were parallelized into 3 groups based on their CMJ height: deep front squats (FSQ, n = 20), deep back squats (BSQ, n = 20), and quarter back squats (BSQ», n = 19). In addition, a control group (C, n = 16) existed (mean age: 24.38 ± 0.50 years). Experimental groups trained 2 d·wk for 10 weeks with a strength-power block periodization, which produced significant (p ≤ 0.05) gains of the specific squat 1RM. The FSQ and BSQ attained significant (p ≤ 0.05) elevations in SJ and CMJ without any interaction effects between both groups (p ≥ 0.05). The BSQ» and C did not reveal any significant changes of SJ and CMJ. The FSQ and BSQ had significantly higher SJ scores over C (p ≤ 0.05). The BSQ did not feature any significant group difference to BSQ» (p = 0.116) in SJ, whereas FSQ showed a trend toward higher SJ heights over BSQ» (p = 0.052). The FSQ and BSQ presented significantly (p ≤ 0.05) higher CMJ heights over BSQ» and C. Posttest in MVC and MRFD demonstrated no significant changes for BSQ. Significant declines in MRFD for FSQ in the right leg (p ≤ 0.05) without any interaction effects for MVC and MRFD between both FSQ and BSQ were found. Training of BSQ» resulted in significantly (p ≤ 0.05) lower MRFD and MVC values in contrast to FSQ and BSQ. Quarter squat training elicited significant (p ≤ 0.05) transfer losses into the isometric maximal and explosive strength behavior. These findings therefore contest the concept of superior angle-specific transfer effects. Deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared with quarter squats.
