Different patterns of physical activity are equally effective in reducing postprandial triacylglycerol concentrations in young men

Background: Public health guidelines on physical activity recommend that adults accumulate 30 minutes of moderate intensity activity on most, preferably all, days of week (Department of Health UK, 2004; Pate et al., 1995). The guidelines also included the caveat that the minimum duration of any one bout should be 10 minutes. However, if total energy expenditure is the most important factor for health benefits, as is suspected (Pate et al., 1995), then the duration of exercise should not matter provided that sufficient energy is expended. The acute effect of a total of 30 minutes of accumulated exercise in bouts shorter than 10 minutes per session throughout the day on postprandial triacylglycerol concentrations has not been determined. Here we report the findings from two studies which compare the effects of accumulating ten, three-minute bouts of exercise versus one, 30-minute bout of exercise on postprandial triacylglycerol concentrations. Methods: Ten male subjects, aged 23±1 years (mean±SE) (running study) and 15 male subjects, aged 25±1 years (walking study) completed three, 2-day trials at least one week apart in a randomised, repeated measures design. On day 1, subjects rested (no exercise) or ran at 70% of maximum oxygen uptake (running study)/walked briskly at a self-selected pace (walking study) in either ten, three-minute bouts (i.e. 09:30 AM to 15:30 PM) with 30 minutes rest between each, or one continuous 30-minute bout (i.e. 15:00 to 15:30 PM). On day 2, subjects rested and consumed test meals (0.69 g fat, 0.95 g carbohydrate, 0.31 g protein, and 46 kJ/kg body mass) for breakfast and lunch. Venous blood samples were collected in the fasted state and for 7 h postprandially on day 2. Results: In both the running and the walking studies postprandial plasma triacylglycerol concentrations were significantly (two-way ANOVA, P<0.05) lower throughout day 2 on the accumulated and continuous exercise trials compared with the control trials: time-averaged postprandial concentrations 1.86 ± 0.32 versus 1.79 ± 0.33 versus 2.37 ± 0.45 mmol/L respectively for the running study and 1.33 ± 0.09 versus 1.36 ± 0.11 versus 1.62 ± 0.15 mmol/L respectively for the walking study. There were no significant differences between the accumulated and continuous exercise trials. Conclusion: These data demonstrate that: 1) accumulated physical activity is at least as effective as continuous physical activity in reducing postprandial plasma triacylglycerol concentrations in young men and 2) both walking and running are effective in reducing postprandial plasma triacylglycerol concentrations in young men.