Exhaustive exercise modifies oxidative stress in smoking subjects.

BACKGROUND

Exhaustive exercise is associated with increased metabolic rate and accelerated generation of reactive oxygen species. Cigarette smoke also contains oxidants that may participate in the development of atherosclerosis. However, data on the association between exercise and smoking are sparse.

METHODS

A homogenous group of 30 young men (15 smokers and 15 nonsmokers; mean age, 23.7 +/- 2.6 years), healthy, trained subjects, were assessed before and after a standard maximal exercise test.

RESULTS

Exercise led to increased protein oxidation (carbonyl assay) in both smokers (+17.7%, P < 0.001) and nonsmokers (+19.1%, P < 0.05), elevation in plasma conjugated dienes (+ 157%, P < 0.04), and plasma lipid peroxides (+14%, P < 0.059) in smokers versus nonsmokers after exercise. Plasma antioxidants levels were significantly lower in the smoking group, with reduction in total carotenoids (-36.5%, P < 0.001), vitamin A (-80%, P < 0.001), and vitamin E (-64%, P < 0.002), compared with nonsmokers. A significant rise in leakage of muscle enzymes (CPK, LDH) and urine proteins (microalbumin and myoglobin) occurred in all subjects after exercise. CRP levels were higher in smokers compared with nonsmokers before and after exercise.

CONCLUSIONS

Our results suggest that unnoticed interaction exists between smoking and intense exercise, which indicates that smokers are more susceptible to oxidative insults probably due to lower antioxidant capacity.