Maximum strength and vertical jump : effects of electromyostimulation versus isometric training

Aim. The aim of this study was to compare the effects of electromyostimulation (EMS) and maximal voluntary isometric contraction (MVC) training on lower limb maximal strength and vertical jump ability. Methods. A 3-group parallel, controlled and longitudinal (pre and post follow-up) design was used. Twenty-five physically active subjects (mean age 28.4±5 yrs, height 177±10 cm, body mass 75.6±12.0 kg) were assigned to 3 groups: EMS training group (EMS, N=10), isometric training group (ISO, N=10) and control group (CON, N=5). Subjects trained 3 times a week for 5 weeks. MVC on a leg press and vertical jumps with (CMJ) and without (SJ) countermovement were measured before (Pre), at 1 week (Post7) and 3 weeks (Post21) after the end of the training period. In each training session, subjects completed 5 s of EMS or MVC with a 30-s rest for a total of 10 min. Statistical analysis was carried out using two-way ANOVA and the post hoc Bonferroni test. Results. The main factor ''time'' (Pre, Post7 and Post21) and group-time interaction were found to be significant (P<0.0001). Post hoc analysis showed significant improvement in MVC (~11%; P<0.001), SJ (10%; P<0.001) and CMJ (8%; P<0.05) in the EMS group only. Conclusion. The results of this study suggest that EMS improves lower limb maximal strength and vertical jump ability in healthy recreationally active subjects. However, the lack of improvement in the ISO group might have been related to the training protocol used in the present study.