The Effect of an Acute Bout of Exercise on Postprandial Metabolic Responses in Younger and Older Adults

Over 370,000 Americans, primarily between the ages of 60 and 79, die annually as a result of cardiovascular disease caused by physical inactivity and a diet that is calorically dense and high in fat. Current findings in young and middle-aged adults suggest that acute exercise with energy expenditure in excess of 500 kcals, may attenuate the deleterious health effects caused by consuming the typical American meal. Purpose:The purpose of this study was to examine the effects of acute exercise and aging on postprandial lipemia (PPL) and postprandial glycemia (PPG). We hypothesized that aerobic exercise performed prior to the consumption of a high-fat meal will attenuate PPL and PPG in younger and older adults. Methods: 12 younger adults (Y: 20-32 yrs) and 12 older adults (O: 61-77 yrs) completed an exercise test to determine peak oxygen consumption (VO2peak). On two separate occasions subjects consumed a high fat meal (HFM) consisting of 12 kcals/kg bodyweight. Blood samples were collected at 30-minute intervals over a 6-hour period to determine postprandial triglycerides, cholesterol, and glucose. Twelve hours prior to one of the HFM challenges, subjects exercised on a cycle ergometer at 65% VO2peakto expend 75% of the kilocalories they would be consuming in the HFM the next day. Results:There was a significant main effect for time for PPTG where PPTG levels increased postprandially (p \u3c 0.001), regardless of exercise condition. There was a significant time x condition interaction for glucose where acute exercise significantly attenuated PPG in Y, but not in O (p = 0.041). There was no significant main effect for time for total cholesterol (p = 0.082). There were no time x age x condition interactions for any measures. Conclusions: The difference in time to peak PPTG in O suggests that an acute exercise session performed prior to consuming a HFM can help to shorten the duration that older adults experience elevated plasma triglycerides after a high fat meal. The reduction in PPG in Y but not in O suggests that in healthy older individuals, aging may reduce the impact of acute exercise on PPG