Order effects of combined strength and endurance training on testosterone, cortisol, growth hormone, and IGF-1 binding protein 3 in concurrently trained men.

Concurrent training (CT) has been widely used in fitness centers to simultaneously optimize cardiovascular and neuromuscular fitness, and induce a high-energy expenditure. Therefore, the aim of this study was to compare the acute effects of 2 different orders of CT on hormonal responses in concurrently trained men. Fourteen men (mean ± SD: 24.7 ± 5.1 years) were randomly divided into 2 groups: endurance training followed by strength (ES, n = 7) and strength training followed by endurance (SE, n = 7). Serum concentrations of testosterone, cortisol, growth hormone, and IGF-1 binding protein 3 (IGFBP-3) were measured before and after both training orders. A significant interaction between exercise order and time was only found in the IGFBP-3 levels (p = 0.022). The testosterone and IGFBP-3 concentrations significantly increased in the ES group after the exercise trainings (57.7 ± 35.1%, p = 0.013 and 17.0 ± 15.5%, p = 0.032, respectively) but did not change significantly in the SE group (15.5 ± 36.6%, p = 0.527 and -4.2 ± 13.9%, p = 0.421, respectively). Conversely, cortisol and growth hormone concentrations significantly increased in both ES (169.2 ± 191.0%, p = 0.021 and 13,296.8 ± 13,009.5%, p = 0.013, respectively) and SE (92.2 ± 81.5%, p = 0.017 and 12,346.2 ± 9714.1%, p = 0.001, respectively) groups compared with baseline values. No significant correlations were found between the changes in the hormonal concentrations. In conclusion, these results suggest that immediately postexercise testosterone and IGFPB-3 responses are significantly increased only after the ES order. Therefore, an ES training order should be prescribed if the main focus of the training intervention is to induce an acute postexercise anabolic environment.