Physiological and cytokine response to acute exercise under hypoxic conditions: a pilot study.

Background: Studies have demonstrated that exercise in hypoxia situations induces a cytotoxicity effects. However, the cytokines participation in this condition is remaining unknown. Thus, the aim the present study was to evaluate physiological parameters and inflammatory profiles in response to acute exercise after five hours of hypoxic conditions.

Methods: Fourteen healthy men were distributed randomly into two groups: normoxic exercise (N.=7) and hypoxic exercise (N.=7). All volunteers were blinded to the protocol. Initially, all subjects were submitted to chamber normobaric in a room fitted for altitude simulations of up to 4500 m, equivalent to a barometric pressure of 433 mmHg. All analyses began at 7:00 a.m. and was maintained for 5 hours; the fraction of inspired oxygen (FiO2) was 13.5%. The groups began a 60-minute session of physical exercise starting at 11:00 a.m., at 50% of peak VO2 (50% VO2peak). Blood was collected for cytokine analysis in the morning upon waking, before the 60-minute exercise session and immediately thereafter.

Results: The heart rate during 60 minutes' exercise training was significantly increased in both exercise groups (P<0.05), and the oxygen saturation was reduced under hypoxic conditions during exercise (P<0.05). After exercise, significant increases were found for IL-1ra and IL-10 under hypoxic conditions (P<0.05) and for IL-6 for both groups (P<0.05). TNF-α was not altered under either environmental condition.

Conclusions: Our data demonstrate that acute exercise performance in hypoxic conditions can promotes early inflammatory response, leads for immunosuppression state.