Effect of exercise intensity on Nrf2 signalling in young men.

INTRODUCTION

The transcription factor Nrf2 is the master regulator of antioxidant defence. Recent data indicate a single bout of moderate-intensity stationary cycling at a constant workload upregulates Nrf2 signalling in young, but not older men; however, the role of exercise intensity on Nrf2 activation has not been tested. We hypothesised that a high-intensity interval session would elicit a greater Nrf2 response than moderate aerobic exercise.

METHODS

Nrf2 signalling in response to two 30-min cycling protocols (high-intensity interval and constant workload) was compared in young men (25 ± 1y, n = 16). Participants completed exercise trials in random order with blood collected pre-, immediately post-, and 30-mins post exercise. Five participants completed a control trial without any physical activity. Nrf2 signalling was determined by measuring protein expression of Nrf2 in whole cell and nuclear fractions. Plasma 8-isoprostanes as well as peripheral mononuclear cell glutathione reductase (GR) and superoxide dismutase activity were measured as markers of oxidative stress.

RESULTS

The exercise trials elicited significant increases in nuclear Nrf2 (p < .01), but increases in whole cell Nrf2 did not reach statistical significance. GR activity and plasma 8-isoprostanes increased significantly in response to exercise (p < .05), and GR response was higher in the high-intensity trial (p < .05).

CONCLUSION

Our findings indicate that acute aerobic exercise elicits activation of nuclear Nrf2, regardless of exercise intensity, but that higher-intensity exercise results in greater activity of GR. Future experiments should explore the effect of exercise mode and duration on Nrf2 signalling, and the role of intensity in compromised populations.