Effects of strength and endurance exercise order on endocrine responses to concurrent training

The present study examined the effect of strength and endurance training order on the endocrine milieu associated with strength development and performance during concurrent training. A randomised, between-groups design was employed with 30 recreationally resistance-trained males completing one of four acute experimental training protocols; strength training (ST), strength followed by endurance training (ST-END), endurance followed by strength training (END-ST) or no training (CON). Blood samples were taken before each respective exercise protocol, immediately upon cessation of exercise, and 1 h post cessation of exercise. Blood samples were subsequently analysed for total testosterone, cortisol and lactate concentrations. Ability to maintain 80% 1RM during strength training was better in ST and ST-END than END-ST (both p < .05). Immediately following the respective exercise protocols all training interventions elicited significant increases in testosterone (p < .05). ST and END-ST resulted in greater increases in cortisol than ST-END (both p < .05). The testosterone:cortisol ratio was similar following the respective exercise protocols. Blood lactate concentrations post-training were greater following END-ST and ST than ST-END (both p < .05). Conducting endurance exercise prior to strength training resulted in impaired strength training performance. Blood cortisol and lactate concentrations were greater when endurance training was conducted prior to strength training than vice versa. As such, it may be suggested that conducting endurance prior to strength training may result in acute unfavourable responses to strength training when strength training is conducted with high loads.