Postprandial Oxidative Stress in Exercise Trained and Sedentary Cigarette Smokers

Heather Bell,Richard J Bloomer,Kelsey H Fisher-Wellman

doi:10.1249/01.mss.0000322544.25959.cc

Abstract

We have recently noted that cigarette smokers experience an exaggerated triglyceride (TAG) and oxidative stress response to high fat feeding as compared to nonsmokers. Exercise training has the potential to enhance TAG removal and improve endogenous antioxidant defense; both of which may decrease postprandial oxidative stress. PURPOSE: To compare blood TAG, antioxidant capacity, and oxidative stress biomarkers in exercise-trained and sedentary cigarette smokers of similar age (22±2 yrs) in response to a high fat test meal. METHODS: Exercise-trained (n=10) and sedentary (n=10) cigarette smokers participated in this study. Blood samples were collected before and at 1, 2, 4, and 6 hours following a high fat test meal (1.2 grams of fat and carbohydrate; 0.25 grams of protein per kilogram body mass) and analyzed for TAG, malondialdehyde (MDA), xanthine oxidase activity (XO), hydrogen peroxide (H O ), and trolox equivalent antioxidant capacity (TEAC). Antioxidant enzyme activity (superoxide dismutase {SOD}, glutathione peroxidase {GPx} and catalase {CAT}) were analyzed in pre meal blood samples. RESULTS: Although the activities of SOD, GPx, and CAT were generally higher for trained compared to sedentary smokers, none of these differences were statistically significant (p>0.05). Training status main effects were noted for MDA (p=0.0057) and TEAC (p=0.0197), with higher MDA and lower TEAC noted for sedentary compared to trained smokers. Time main effects were noted for all variables (p<0.02), with values higher than pre meal at times from 2-6 hours post meal (p<0.05). No training status by time interaction was noted for any variable; however, contrasts revealed lower values for trained compared to sedentary subjects at 4 (p=0.017) and 6 (p=0.039) hours post meal for MDA. CONCLUSION: Exercise training status does not influence postprandial lipemia or oxidative stress in a sample of young cigarette smokers, with the exception of lower MDA during the 4-6 hour post feeding period.

Highlights

Oxidative stress involves the production of reactive oxygen species (ROS) to an extent that overwhelms the antioxidant defense system [1]
Due to the fact that no studies to date have investigated the effect of exercise training on postprandial oxidative stress in smokers, we had limited data to use in a power analysis for the current design
Antioxidant enzyme activities were slightly higher for trained compared with untrained smokers, no statistically detected differences were noted for Catalase activity (CAT), Superoxide dismutase activity (SOD), or Glutathione peroxidase activity (GPx) activity (p>0.05; Table 3)

Summary

Introduction

Oxidative stress involves the production of reactive oxygen species (ROS) to an extent that overwhelms the antioxidant defense system [1]. Increased production of ROS promotes the oxidation of lipids and other molecules in ways that impair cellular function, possibly leading to disease [2, 3]. Cigarette smoking exacerbates ROS formation [4], evidenced by the increase in oxidative stress biomarkers in smokers compared with nonsmokers [5,6,7]. Cigarette smoke-induced oxidative stress poses a significant human health concern, especially as related to cardiovascular disease [8].

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Discussion

Conclusion