Substrate oxidation during exercise: impact of time interval from the last meal in obese women.
OBJECTIVE
To investigate whether time interval between meal and exercise alters the balance of substrate oxidation during an exercise bout.


OBJECTIVE
Exercise performed 3-h after meal induces a higher rate of lipid oxidation than when performed only 1-h after meal.


METHODS
Eight overweight and obese postmenopausal women (age: 57.4+/-2.4 y; BMI: 31.8+/-2.1 kg m(-2); %FAT: 42.7+/-1.2%, mean+/-s.e.m.) performed two sessions of exercise training at an intensity corresponding to their ' crossover' point of substrate oxidation (COP(ox)). 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+38.9+/-2.7 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 (78+/-5 vs 87+/-5 bpm; P<0.05). Glycemia, lactatemia and insulinemia were reduced when exercise was performed 3 h after meal (P<0.05).


CONCLUSIONS
When exercise is performed 3 h after meal at an intensity corresponding to the COP(ox), 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.
Dumortier
M
M
Service Central de Physiologie Clinique, Centre d'Exploration et de Réadaptation des Anomalies du Métabolisme Musculaire, Hôpital Lapeyronie, Montpellier Cedex 5, France. muriel_dum@yahoo.fr
Thöni
G
G
Brun
J F
JF
Mercier
J
J
D000704:Analysis of Variance; D001786:Blood Glucose / Q000032:analysis; D002153:Calorimetry, Indirect; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D015227:Lipid Peroxidation; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism* / Q000628:therapy; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D019344:Lactic Acid