Paper
International Journal of Obesity (2005) 29, 966–974. doi:10.1038/sj.ijo.0802991; published online 17 May 2005
Substrate oxidation during exercise: impact of time interval from the last meal in obese women
M Dumortier1, G Thöni2, J F Brun1 and J Mercier1
- 1Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire (CERAMM), Hôpital Lapeyronie, Montpellier Cedex 5, France
- 2Laboratoire des Adaptations Cardiovasculaire à l'Exercice, Faculté des Sciences, 33 Rue Louis Pasteur, Avignon, France
Correspondence: Dr M Dumortier, Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire (CERAMM), CHU Lapeyronie, 34295 Montpellier Cedex 5, France. E-mail: muriel_dum@yahoo.fr
Received 4 April 2004; Revised 22 September 2004; Accepted 25 February 2005; Published online 17 May 2005.
Abstract
OBJECTIVE:
To investigate whether time interval between meal and exercise alters the balance of substrate oxidation during an exercise bout.
HYPOTHESIS:
Exercise performed 3-h after meal induces a higher rate of lipid oxidation than when performed only 1-h after meal.
RESEARCH METHODS AND PROCEDURES:
Eight overweight and obese postmenopausal women (age: 57.4
2.4 y; BMI: 31.82.1 kg m-2; %FAT: 42.71.2%, means.e.m.) performed two sessions of exercise training at an intensity corresponding to their ' crossover' point of substrate oxidation (COPox). One session was held 1 h after a standardized meal and the other, 3 h after an identical meal on another day. Substrate oxidation was evaluated by indirect calorimetry. Hormonal responses were investigated during exercise.
RESULTS:
Respiratory exchange ratio values were lower in the 3-h condition, showing higher lipid oxidation during exercise (average difference+38.92.7 mg min-1; P<0.001), while mean energy expenditure did not differ. Basal heart rate was reduced in the 3 h compared with the 1-h condition (785 vs 875 bpm; P<0.05). Glycemia, lactatemia and insulinemia were reduced when exercise was performed 3 h after meal (P<0.05).
DISCUSSION:
When exercise is performed 3 h after meal at an intensity corresponding to the COPox, metabolic and hormonal responses are similar to those targeted during the submaximal exercise test performed at fast that we previously proposed to individualize exercise training in the obese.
Keywords:
indirect calorimetry, lipid oxidation, energy expenditure
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