title: Towards optimizing the timing of the pre-exercise meal.
abstract: The purpose of this study was to compare the effect a 6-hr versus 3-hr prefeeding regimen on exercise performance. The subjects were 8 active women (21.4 +/- 0.9 years, 60.4 +/- 2.4 kg, 19.9 +/- 1.3% body fat, and 165.6 +/- 2.1 cm). All women completed 2 exercise trials (separated by 3-6 d) on a treadmill where they ran at moderate intensity for 30 min with 30-s sprints at 5-min intervals, followed directly by increasing incrementally the grade until volitional fatigue was achieved. The exercise trials were performed 3 hr and 6 hr after consuming 40 +/- 3 kJ/kg meal. Time to exhaustion was 0.75 min shorter (p =.0001) for the 6-H trials compared to the 3-H trials. There were no significant differences in submaximal or peak oxygen uptake, heart rate, or rating of perceived exertion (p >.05). The 6-H trials compared to the 3-H trials resulted in.05 lower RERs (p =.0002), and a 2 mmol lower blood lactate at exhaustion (p =.012). Blood glucose levels and cortisol responses to exercise were similar between trials (p >.05). However, both resting and post exercise insulin levels were lower during 6-H trials. It was concluded that performance of moderate- to high-intensity exercise lasting 35-40 min is improved by consuming a moderately-high carbohydrate, low fat, low protein meal 3-hr before exercise compared to a similar meal consumed 6 hr prior to exercise. Thus, athletes should not skip meals before competition or training sessions.
authors.affiliation: Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Maffucci
authors.forename: R G
authors.initials: RG
authors.lastname: McMurray
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose; D004032:Diet; D004435:Eating / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005221:Fatigue; D005260:Female; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D007773:Lactates