J Am Coll Cardiol. 2004;44(12):2375-2382.

Background

Endothelial function is impaired after fat ingestion, the degree of which appears to be proportional to the increase in postprandial lipemia. It has been suggested that moderate exercise can reduce postprandial lipemia.

Objective

The authors hypothesized that a session of exercise prior to fat ingestion can also attenuate the impairment of endothelial function seen in the postprandial state. A secondary aim was to investigate whether these exercise-induced changes would differ between 2 groups of subjects with different metabolic profiles.

Methods

Two groups of middle-aged men-10 centrally obese and 10 lean-were enrolled in the study. These subjects differed in insulin sensitivity and insulin-regulated postprandial glucose and lipid metabolism. Subjects underwent 2 oral fat tolerance tests; subjects walked on a treadmill for 90 minutes at an intensity of 50% of the maximal oxygen uptake before one test, and were sedentary before the other test (control). Endothelium-dependent and endothelium-independent forearm microvascular function was assessed using laser Doppler imaging.

Results

Exercise significantly reduced (by 25%) postprandial triglyceride concentrations in both the lean and centrally obese groups. Fasting and postprandial microvascular responses to acetylcholine (endothelium-dependent) were 25% and 15% higher, respectively, after exercise compared to control. On the other hand, response to 1% sodium nitroprusside (endothelium-independent) was not different in the fasted state but was 20% higher postprandially after exercise compared to control. Exercise-induced improvement in endothelial function did not differ between the 2 groups and was sustained up to the day after a single exercise session.

Conclusion

This study showed that a single session of moderate exercise significantly improved small vessel vasodilator function in both the fasted and postprandial states in centrally obese and lean middle-aged men. This effect was sustained up to 24 hours after exercise. This study suggests that moderate exercise is effective in attenuating many of the adverse metabolic and vascular changes seen after ingestion of dietary fat.

Comments

The novel finding in this study is that the beneficial effects of exercise on postprandial endothelial function can be sustained up to 24 hours after a single session of moderate exercise. Extrapolating this finding would suggest that moderate exercise performed regularly could result in maintenance of endothelial health, which may impact on cardiovascular risk. Even inactive centrally obese subjects were able to tolerate the moderate exercise session used in this study. As clinicians, we can use studies such as this in helping to motivate our patients to engage in an active lifestyle.