Improved maximal strength is not associated with improvements in sprint time or jump height in high-level female football players: a cluster-randomized controlled trial

Abstract

Background Maximal strength increments are reported to result in improvements in sprint speed and jump height in elite male football players. Although similar effects are expected in females, this is yet to be elucidated. The aim of this study was to examine the effect of maximal strength training on sprint speed and jump height in high-level female football players. Methods Two female football teams were team-cluster-randomized to a training group (TG) performing maximal strength training (MST) twice a week for 5 weeks, or control group (CG) doing their regular pre-season preparations. The MST consisted of 3–4 sets of 4–6 repetitions at ≥85% of 1 repetitions maximum (1RM) in a squat exercise. Sprint speed and jump height were assessed in 5-, 10- and 15 m sprints and a counter-movement jump (CMJ) test, respectively. Nineteen participants in TG (18.3 ± 2.7 years) and 14 in CG (18.3 ± 2.4 years) completed pre- and posttests and were carried forward for final analyses. Results There was no improvement in neither of the sprint times (p > 0.36), nor jump height (p = 0.87). The players increased their 1RM in squats (main of effect of time: p < 0.00, pη2 = 0.704), and an interaction effect of time x group was observed (p < 0.00, pη2 = 0.516) where the TG increased their 1RM more than the CT (between subjects effects: p < 0.001, pη2 = 0.965). Conclusions MST improved maximal strength in female football players to a large extent; however, the improvement in maximal strength did not result in any transference to sprint speed or jump height. Trial registration This study was registered at clinicaltrials.gov PRS (Protocol registration and results System) with the code NCT04048928, 07.08.2019, retrospectively registered.

Effects of Strength vs. Plyometric Training Programs on Vertical Jumping, Linear Sprint and Change of Direction Speed Performance in Female Soccer Players: A Systematic Review and Meta-Analysis

“…The selected studies were submitted to the PEDro methodological quality scale. Two studies obtained a score of 9/10 [ 36 , 37 ], one study obtained 8/10 [ 38 ], six obtained 7/10 [ 5 , 6 , 39 , 40 , 41 ], two obtained 5/10 [ 42 , 43 ], and two obtained 4/10 [ 44 , 45 ]. Table 1 displays the complete and detailed PEDro scale score of each study.…”

“…The purpose of ST is to promote maximal strength and muscular hypertrophy to improve physical performance [ 22 ], and this method has often been used by physical trainers in soccer training routines [ 7 , 47 ]. Two studies by Pardos-Mainer et al [ 5 , 6 ] found that ST exerted a borderline small–moderate effect on vertical jump performance whilst Lindblom et al [ 39 ] and Pedersen et al [ 38 ] resulted only a trivial ES, and even the effect was negative. It is possible that the exercises included in the ST programs do not demonstrate a significant transference effect to soccer-specific physical performance and conditioning programs with higher load and intensity would be necessary in order to benefit from the training [ 8 , 35 ]…”

“…Subgroup analyses of programming parameters revealed that ST interventions were more effective with longer study durations (8 weeks or more), greater training frequency (2 sessions or more per week), more training sessions (16 or more) and longer session times (30 min or more) to improve vertical jump performance. However, only four studies [ 5 , 6 , 38 , 39 ] provided data and, owing to the homogeneity of programming parameters used across studies, more research, utilizing varying study durations, amounts of sessions, training sessions and session times, should be carried out to establish more robust recommendations regarding these parameters.…”

“…In this sense, the large effect observed in training sessions and session times may be inflated, probably related with the results from Ozbar et al [ 42 ], Sedano-Campo et al [ 43 ] and Rubley et al [ 44 ]. Two [ 38 , 40 ] of these three studies showed a moderate–large effect on vertical jump performance (ES = 0.87–2.21) after the PT program. Such substantial improvements may be related to the initial vertical jump values of female soccer players, which are too high compared to the rest of the studies included in the current meta-analysis.…”

Joint Flexibility and Isometric Strength Parameters Are Not Relevant Determinants for Countermovement Jump Performance

“…For the dynamic strength measurements, the participant was asked to perform three CMJs, with a 1-min rest in between, on a transportable force platform (Quattro Jump, Kistler GmbH, Winterthur, Switzerland, 500 Hz recording frequency). Start and end position was upright, in a hip-wide standing position, with hands placed on the hips [ 16 ]. The hands were not allowed to be moved during the whole measurement, in order not to influence the jump height [ 17 ].…”