Effects of Exercise Intensity on Cortisol, Antioxidant, and DNA damage in Smokers and Non‐Smokers

Abstract

The purpose of the study was to examine blood level changes of cortisol, total antioxidant status, and 8‐oxo deoxyguanisine (8‐OXO) before and after exercise at different intensities in smokers and non‐smokers.MethodsFourteen physically inactive smokers and non‐smokers were recruited. Each subject completed three treadmill runs at different intensities in a random order (60%, 70%, and 80% of VO2max). Running distance for all three runs was equivalent to a 30‐min run at 70% VO2max. Blood samples were collected at rest (PRE), immediately after (POST), and 1 hour following (1H) each run.ResultsSmokers (SM) showed higher levels of Cortisol (P=.043) and 8‐OXO (p=.024) and lower level of antioxidant (P=.001) as compared to non‐smokers (NS) (group effect). Cortisol levels were elevated in both SM and NS following the 80% VO2max run [SM (PRE:611.9±13.6nmol/L→POST:761.6±16.2, Mean±SE, P=.0001); NS(498.2±13.9→624.2±16.2, P=.0001)]. Total antioxidant increased only in SM following runs (60%:1.58±.04mM→1.76±.06, P=.0001; 70%:1.57±.04→1.72±.08, P=.001; 80%:1.59±.04→1.71±.09, P=.012). 8‐OXO elevated at POST following 70% (SM:3188±242pg/mL→4667±199, P=.001; NS:2432±181→3586± 199, P=.011 ) and 80% (SM: 3268±234→5832±488, P=.0001; NS:2473±200→3813±255, P=.003) VO2max runs.ConclusionHigher levels of cortisol and lower antioxidant status induced greater DNA damage in smokers, especially following runs at 70% and 80% VO2max, indicating that DNA damage in blood immune cells following moderate‐high and high intensity aerobic exercises is greater in Smokers than Non‐Smokers. Therefore, smokers may need to avoid high intensity aerobic exercise since combined stress from exercise and chronic smoking may aggravate immune function.