The acute effects of walking exercise intensity on systemic cytokines and oxidative stress

Abstract

Oxidative stress is associated with tissue cytokine secretion although the precise mechanism(s) underpinning this relationship during high intensity intermittent exercise remains unclear. This study investigates the acute response to a bout of high intensity intermittent walking (HIIW), compared to continuous moderate intensity walking (CMW), on various cytokines and biomarkers of oxidative stress. Seventeen (n = 17) apparently healthy male participants (aged 22.6 ± 4.6 years; $$\dot{V}{\text{O}}_{2} \max$$ : 53.7 ± 7.1 ml kg−1 min−1) undertook a randomised crossover study consisting of two exercise trials: (1) HIIW requiring 3 × 5 min bursts at 80% $$\dot{V}{\text{O}}_{2} \max$$ (each separated by 5 min of walking at 30% $$\dot{V}{\text{O}}_{2} \max$$ ) and (2) CMW (60% $$\dot{V}{\text{O}}_{2} \max$$ for 30 min). Each trial was separated by 7 days. Venous blood samples were obtained pre-exercise, post-exercise and at 2, 4, 24 and 48 h post-exercise for determination of systemic inflammation (IL-6 and TNF-α), lipid soluble antioxidants and oxidative stress (LOOH, H2O2 and the ascorbyl free radical). Both IL-6 and TNF-α increased immediately post exercise, regardless of intensity and remained elevated until at least 4 h (main effect for time; p < 0.05). While there was no change in either lipid peroxidation or free radical metabolism (Asc· and H2O2), α-tocopherol increased (pooled HIIW and CMW, p < 0.05), whereas lycopene decreased at 2 h post HIIW (p < 0.05). Bouts of both HIIW and CMW promote cytokine secretion post exercise, and this seems to be independent of oxidative stress. Further investigation is required to assess how such changes may underpin some of the transient health benefits of exercise.