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  • Author: David J. Stensel x
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Masashi Miyashita, Stephen F. Burns and David J. Stensel

The current study investigated the acute effects of accumulating short bouts of running on circulating concentrations of postprandial triacylglycerol (TAG) and C-reactive protein (CRP). Ten men, age 21–32 yr, completed two 1-d trials. On 1 occasion participants ran at 70% of maximum oxygen uptake in six 5-min bouts (i.e., 8:30, 10, and 11:30 a.m. and 1, 2:30, and 4 p.m.) with 85 min rest between runs. On another occasion participants rested throughout the day. In both trials, participants consumed test meals at 9 a.m. and 12 p.m. In each trial, venous blood samples were collected at 8:30, 10, and 11:30 a.m. and 1, 2:30, 4, and 5:30 p.m. for plasma TAG measurement and at 8:30 a.m. and 5:30 p.m. for serum CRP measurement. Total area under the curve for plasma TAG concentration versus time was 10% lower on the exercise trial than the control trial (M ± SEM: 13.5 ± 1.8 vs. 15.0 ± 1.9 mmol · 9 hr−1 · L−1; p = .004). Serum CRP concentrations did not differ between trials or over time. This study demonstrates that accumulating short bouts of running reduces postprandial plasma TAG concentrations (a marker for cardiovascular disease risk) but does not alter serum CRP concentrations.

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Stephen F. Burns, Masashi Miyashita, Chihoko Ueda and David J. Stensel

The present study examined how multiple bouts of resistance exercise, performed over 1 d, influence 2 risk factors—postprandial triacylglycerol (TAG) and serum C-reactive-protein (CRP) concentrations—associated with coronary heart disease. Twenty-four men age 23.5 (SD 3.4) y completed two 2-d trials, exercise and control, at least 1 wk apart in a counterbalanced randomized design. On day 1 of the exercise trials participants completed 20 sets of 15 repetitions of 5 different resistance exercises divided into five 45-min bouts of exercise—100 sets and 1500 repetitions in total for all exercises. Exercises were performed at 30–40% of 1-repetition maximum. Blood samples were taken before and after exercise. On day 1 of the control trial participants were inactive, with blood samples taken at time points corresponding to the exercise trial. On day 2 of both trials participants consumed a test meal (0.89 g fat, 1.23 g carbohydrate, 0.4 g protein, 60 kJ per kg body mass). Blood samples were obtained fasted and for 6 h post prandially. Total area under the postprandial TAG concentration versus time curve was 12% lower in the exercise than in the control trial (8.76 [3.54] vs. 9.94 [4.31] mmol·L-1·6 h, respectively; P = 0.037). Serum CRP concentrations did not change over the 2 d in the control trial but increased in the exercise trial: trial × time interaction (P = 0.028). Multiple bouts of resistance exercise reduce postprandial TAG concentrations but increase serum CRP concentrations. The extent to which these findings are clinically relevant requires further study.

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Jesudas E. Menon, David J. Stensel, Keith Tolfrey and Stephen F. Burns

Purpose: This study examined how manipulating meal frequency, with and without exercise, affects postprandial triacylglycerol (TAG). Methods: Fourteen sedentary men completed four 2-day trials in a noncounterbalanced random cross-over order: (1) consumption of 1 large high-fat milkshake without exercise (1-CON), (2) consumption of 2 smaller high-fat milkshakes without exercise (2-CON), (3) consumption of 1 large high-fat milkshake with exercise (1-EX), and (4) consumption of 2 small high-fat milkshakes with exercise (2-EX)—total energy intake was standardized across trials. On day 1, participants rested (1-CON and 2-CON) or walked briskly for 60 minutes (1-EX and 2-EX). On day 2, participants consumed either a single large high-fat milkshake (75% fat; 1-CON and 1-EX) for breakfast or 2 smaller isoenergetic milkshakes (2-CON and 2-EX) for breakfast and lunch. Plasma TAG were measured fasting and for 7 hours after breakfast. Results: Peak incremental TAG was 30% lower on 2-EX than 1-CON (P = .04, d = 0.38). Postprandial TAG increased more rapidly in the first 4 hours in 1-CON than other trials; but at 6 hours, TAG was exaggerated in 2-CON compared with 1-CON. Conclusions: Increasing meal frequency after exercise, without altering overall fat intake, attenuates postprandial TAG.