GLUCOSE AND LACTATE KINETICS DURING A SHORT EXERCISE BOUT IN PREGNANCY

Pregnancy is considered diabetogenic. Although exercise has been advoc ated to assist in metabolic control of the nonpregnant diabetic indivi dual, there is a paucity of data about the metabolic effects of exerci se during pregnancy. To examine whether moderate exertion may be benef icial in the maintenance of maternal carbohydrate homeostasis, glucose and lactate kinetics were measured in the third trimester in five pre gnant nondiabetic women (gestational age, 34.2 +/- 0.1 weeks [mean +/- SE]) by infusion of 45 mu g . kg(-1). min(-1) [6,6-H-2(2)]glucose and 70 mu g . kg(-1). min(-1) [U-C-13]lactate tracers. Subjects were obse rved at rest for determination of baseline steady-state kinetics over a 30-minute period, and then they exercised for 30 minutes at 60% maxi mum oxygen consumption (Vo(2)max) and were evaluated for 30 minutes po stexercise. Glucose and lactate kinetics and lactate oxidation were me asured throughout the exercise protocol. This study was repeated postp artum in all individuals at least 6 weeks after delivery. Compared wit h the steady-state preinfusion period, plasma glucose concentration wa s not elevated during exercise in either group, nor was plasma lactate concentration significantly different in either group. Glucose kineti cs did not change during exercise, but lactate kinetics increased in b oth groups. Vo(2) and percent of lactate C contribution to CO2, an ind ication of lactate oxidation, increased proportionally in both groups during exercise. Metabolic perturbations, as measured by glucose and l actate kinetics, do not appear to be different during the third trimes ter of pregnancy during a relatively short bout of exercise compared w ith the nonpregnant state. Copyright (C) 1996 by W.B. Saunders Company .