Aerobic exercise increases resistance to oxidative stress in sedentary older middle-aged adults. A pilot study

Abstract

Older individuals who exercise regularly exhibit greater resistance to oxidative stress than their sedentary peers, suggesting that exercise can modify age-associated loss of resistance to oxidative stress. However, we recently demonstrated that a single bout of exercise confers protection against a subsequent oxidative challenge in young, but not older adults. We therefore hypothesized that repeated bouts of exercise would be needed to increase resistance to an oxidative challenge in sedentary older middle-aged adults. Sedentary older middle-aged men and women (50-63 years, n = 11) participated in an 8-week exercise intervention. Maximal oxygen consumption was measured before and after the intervention. The exercise intervention consisted of three sessions per week, for 45 min at an intensity corresponding to 70-85 % maximal heart rate (HR_max). Resistance to oxidative stress was measured by F₂-isoprostane response to a forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial before and after the exercise intervention. The intervention elicited a significant increase in maximal oxygen consumption (VO_2max) (P < 0.0001). Baseline levels of F₂-isoprostanes pre- and post-intervention did not differ, but the F₂-isoprostane response to the I/R trial was significantly lower following the exercise intervention (time-by-trial interaction, P = 0.043). Individual improvements in aerobic fitness were associated with greater improvements in the F₂-isoprostane response (r = -0.761, P = 0.011), further supporting the role of aerobic fitness in resistance to oxidative stress. These data demonstrate that regular exercise with improved fitness leads to increased resistance to oxidative stress in older middle-aged adults and that this measure is modifiable in previously sedentary individuals.

Keywords: Aging; F2-isoprostanes; Ischemia-reperfusion; Redox balance.

Figure 1

Plasma F₂-isoprostane response to the I/R trial pre- and post-exercise intervention. All values are mean ± SEM. Change across time before and after the 8-week exercise intervention. The time period between pre and post on the x-axis denotes the forearm ischemia/reperfusion trial. Baseline values did not differ between trials (P = 0.887). There was a significant interaction between time (I/R trial) and trial (P = 0.043). In addition, there was a significant main effect of time (P = 0.001) but not of trial (P = 0.421)

Figure 2

Relationship between changes in aerobic capacity and changes in response to the I/R trial. There was a significant negative Pearson correlation between improvements in relative fitness (VO_2max) and changes in the F₂-isoprostane response to the I/R trial (AUC) following the exercise intervention (r = −0.760, P = 0.011). The solid line denotes the linear regression line of best fit. Dashed lines indicate the 95 % confidence intervals