Interaction between cortisol and tumour necrosis factor with concurrent resistance and endurance training

Objective: To determine the effect of concurrent resistance and endurance training on tumor necrosis factor alpha (TNF alpha), urinary free cortisol, strength [one-repetition maximum (1 RM)], and maximal oxygen consumption (Vo(2)max). Design: Randomized control trial of 12 weeks' duration. Setting: University of Alberta, Edmonton, Alberta, Canada. Participants: Forty-five healthy female (n = 18) and male (n = 27) subjects who had not formally trained for at least 6 months prior to the study but were physically active. The mean +/- SD age, height, and body mass for all subjects were 22.3 +/- 3.3 years, 1.76 +/- 9.32 m, and 73.4 +/- 11.6 kg, respectively. Intervention: The subjects were randomly assigned to four groups: strength training only (S), n = 10; endurance training only (E), n = 11; combined strength and endurance training (SE), n = 13; and a control group (C), n = 10. The S and E groups performed progressively overloaded training sessions three times per week for 12 weeks. The SE group completed the same strength and endurance training programs on different days (i.e., 6 days/week) for 12 weeks. Main Outcome Measures: Serum levels of TNF alpha, urinary free cortisol, 1 RM, and Vo(2)max were measured before and after 6 and 12 weeks of training. Results: Significant increases in leg press and knee extension 1 RM occurred after training in both S and SE groups, but the relative gains in knee extension 1 RM were greater in the S group. Similar increases in Vo,max were observed in groups E and SE (p < 0.05). Cortisol was significantly increased in the SE group for women and decreased in the E group for men after training. TNF alpha was significantly elevated in the women of group E after training. No correlation was observed between urinary free cortisol and TNF alpha with training. Conclusion: These results indicate that a partial interference effect of compromised strength gains in unilateral knee extension of the men occurred after concurrent strength and endurance training that could not be attributed to an interaction between cortisol and TNF alpha in response to this type of exercise.