Effect of ten weeks maximal eccentric and concentric resistance training on muscle force in physically active young men in isokinetic bench press

Introduction. It has been long known that there are differences in eccentric and concentric force productions. Moreover, it has been known that eccentric and concentric resistance training effects differently on force production. This thesis is part of a larger study. The purpose of this study was to investigate how maximal eccentric and concentric resistance training effects maximal eccentric and concentric force production and how maximal eccentric training effects maximal concentric force and maximal concentric training on maximal eccentric force production. Methods. Participants were randomly selected for two intervention groups: one who trained eccentric only (N=11) and one who trained concentric only (N=12). Participants were physically active young men between 21-36 years old. The total number of participants in this study was 23 (N=23). Isokinetic bench press device was used for the trainings and measurements. Angular velocity of the isokinetic bench press was set to 0.2 milliseconds (ms) and the rest period of the bar was set to 2000 ms. Participants went through a ten-week training program. Sets varied from 2-4 and repetitions from 3-4 depending on the phase of the training protocol. Results. Maximal eccentric force did not improve in this intervention by maximal eccentric resistance training (ecc/ecc). Decline was -146 newtons (p = 0.01; -10.3%) compared to pre measurement. This finding is not according to previous studies. Maximal concentric force increased 12.0%% (109 newtons; p = 0.00) among participants in the maximal concentric training group (con/con). Eccentric training had positive influence on maximal concentric force production (ecc/con) (14.1%; p = 0.03). Maximal concentric force increased 86 newtons in eccentric training group. Maximal eccentric force did not increase in concentric training group (con/ecc) (-31; -2.4%; p = 0.69). Statistically significant difference was observed between ecc/ecc vs. con/con training groups (p = 0.00). Discussion. We hypothesized that maximal eccentric resistance training would be associated to increased maximal eccentric force production. This discovery is contradictory to previous studies. One possible explanation for this peculiar outcome can be that the participants were low responders in which strength does not develop as it normally enhances. Another explanation can be that the stimulus of the training protocol was not high enough to give responses in muscle force. This study gives us support that with maximal eccentric resistance training it is possible to enhance maximal concentric strength performance. In addition, maximal concentric resistance training does not enhance eccentric force production. As a practical application it can be said that sports coaches of different sport disciplines, personal trainers and other professionals of sport and health sciences can utilize the information and results of this study in their practical work for enhancing their athletes’ physical performance and wellbeing. It is important to keep in mind that maximal eccentric training does not necessarily develop eccentric force production. Instead, e.g. for cyclists, it can be said that maximal concentric resistance training can enhance their endurance performance.