Effects of prior moderate exercise on postprandial metabolism and vascular function in lean and centrally obese men.

Objectives: We investigated whether a session of prior exercise could ameliorate postprandial endothelial dysfunction.

Background: Endothelial function is impaired after fat ingestion, and this may be related to rises in triglyceride concentrations. Exercise reduces postprandial triglyceride concentrations.

Methods: Ten lean (waist <90 cm) and 10 centrally obese (waist >100 cm) middle-aged men each underwent two oral fat tolerance tests (blood taken fasting and for 8 h after a high-fat meal containing 80 g fat and 70 g carbohydrate). On the afternoon before one test, subjects performed a 90-min treadmill walk (exercise); no exercise was performed before the control test. Endothelium-dependent and -independent microvascular function was assessed using laser Doppler imaging in the fasted state and at two hourly intervals during the 8-h postprandial period.

Results: Exercise reduced both fasting and postprandial triglyceride concentrations by 25% in both the lean and centrally obese groups (p < 0.0005). For all subjects taken together, exercise improved fasting endothelium-dependent function by 25% (p < 0.05), and, although there was a significant postprandial decrease in both endothelium-dependent and -independent function in both the control and exercise trials (p < 0.01), postprandial endothelium-dependent and -independent function were 15% and 20% higher, respectively, in the exercise trial than the control trial (both p < 0.05).

Conclusions: A session of prior exercise improves fasting and postprandial vascular function in middle-aged men. This may be one mechanism by which exercise influences cardiovascular risk.