Comparison of the effects of isometric and dynamic training on strength and body composition in recreational athletes

The aim of this study was to compare the effectiveness of isometric and dynamic contractions of equal duration in terms of strength development and changes in body composition. Methods: Recreational strength-trained men (n=20) were divided into two subgroups that performed an isometric and dynamic contraction protocol. Isometric and dynamic contraction protocols were performed 14 times over a 7-week period and preceded and followed by measurements of maximal weight (1RM – one repetition maximum) using the weightlifting method, MVIC (maximal voluntary isometric contraction) measured on an LR2-P upper limb flexor and extensor torques and body composition made using electrical bioimpedance (BIA) Results: MVIC values increased significantly measured in the angle settings of 30º P= .009, 60º P= .016, 90º P= .048. after isometric training, and after training in dynamic conditions only for the joint angle value of 60º P= .016. MVIC differences between the effects of training in isometric conditions and in dynamic conditions, were significant for angles of 90º P= .044 and 30º P= .002. The 1RM values did not change significantly after both types of training (pre-post isometric vs dynamic). There were no significant changes in active body mass and body fat of the whole body and segmentally of the upper limbs. Conclusions: Given the limited scope and limitations of the study, the use of isometric contractions appears to promote an increase in MVIC values in all angular settings (30, 60, 90°), although the greatest differences between static and dynamic training effects were obtained at 30 and 90°. The lack of significant changes in strength (1RM), active body mass and body fat after the application of both types of training, may indicate an inadequate conversion of the selected loading modality to fitness in these characteristics.