Concurrent endurance and strength training : neuromuscular, cardiorespiratory and hormonal effects of the exercise order in previously untrained and recreationally endurance trained men

The aim of the present thesis was two-fold. First, to investigate physiological adaptations to concurrent endurance and strength training performed in the same session with different exercise orders (i.e. commencing training with endurance or strength, respectively; E+S vs. S+E) in previously untrained men (n=42) (study 1). Second, to examine physiological adaptations when strength training was always performed immediately after endurance running in the same session (E+S) compared to endurance training alone (E) in recreational endurance runners (n=30) (study 2). In study 1, training consisted of 2 - 3 weekly combined endurance cycling and mixed hypertrophic and maximal strength training sessions for 24 weeks. In study 2, all subjects performed 4 - 6 weekly endurance training sessions for 24 weeks, while in E+S an additional strength training session was performed twice a week right after a strenuous endurance running session. In study 1, before the training intervention exercise order-specific differences were observed by statistically reduced testosterone concentrations during recovery following an experimental loading in E+S but not S+E. After 24 weeks of training, however, this initial reduction was no longer observed. Furthermore, increases in en- durance and maximal strength performance, muscle cross-sectional-area and body composition as well as changes in basal hormone concentrations were similar in E+S and S+E, while rapid isometric force production was statistically increased in S+E only. In study 2, no statistical between-group difference was observed in endurance loading- induced acute force and hormone responses before or after the training intervention. In E+S, maximal strength was maintained and lean mass slightly increased, while also no statistical changes in electromyography and voluntary activation were observed. In E, maximal strength statistically decreased during training. Both groups improved en- durance performance to a similar extent. The present thesis showed that in previously untrained men despite an initial between-group difference in testosterone concentrations during recovery, the exercise order did not affect training-induced adaptations in maximal strength and endurance performance or body composition. In recreational endurance runners, prolonged strength training performed always repeatedly after an intense endurance running session did not lead to enhanced endurance performance, possibly attributed to impaired neuromuscular adaptations.