title: Training improves the response in glucose flux to exercise in postmenopausal women.
abstract: We examined the effects of endurance training on parameters of glucose flux during rest and exercise in postmenopausal women. Ten sedentary, but healthy women (55 +/- 1 yr) completed 12 wk of endurance exercise training on a cycle ergometer [5 days/wk, 1 h/day, 65% peak oxygen consumption (Vo(2peak))]. Flux rates were determined by primed continuous infusion of [6,6-(2)H]glucose (D(2)-glucose) during 90 min of rest and 60 min of cycle ergometer exercise during one pretraining exercise trial [65% Vo(2peak) (PRE)] and two posttraining exercise trials [the power output that elicited 65% pretraining Vo(2peak) (ABT) and 65% posttraining Vo(2peak) (RLT)]. Training increased Vo(2peak) by 16.3 +/- 3.9% (P < 0.05). Epinephrine and glucagon were lower during ABT and lactate was lower during ABT and RLT (P < 0.05), but the apparent insulin response was unchanged. Whole body glucose rate of appearance decreased posttraining during exercise at a given power output (4.58 +/- 0.39 mg.kg(-1).min(-1) during ABT compared with 5.21 +/- 0.48 mg.kg(-1).min(-1) PRE, P < 0.05), but not at the same relative workload (5.85 +/- 0.36 mg.kg(-1).min(-1)). Training resulted in a 35% increase in glucose MCR during exercise at the same relative intensity (7.16 +/- 0.42 ml.kg(-1).min(-1) during RLT compared with 5.28 +/- 0.42 ml.kg(-1).min(-1) PRE, P < 0.05). Changes in parameters of glucose kinetics during exercise were accomplished without changes in dietary composition, body weight, or body composition. We conclude that despite changes in the hormonal milieu that occur at menopause, endurance training results in a similar magnitude in training-induced alterations of glucose flux as seen previously in younger women.
authors.affiliation: Dept. of Integrative Biology, 3060 VLSB, Univ. of California, Berkeley, CA 94720-3140, USA.
authors.forename: Zinta A
authors.initials: ZA
authors.lastname: Zarins
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Johnson
authors.forename: Nastaran
authors.initials: N
authors.lastname: Faghihnia
authors.forename: Michael A
authors.initials: MA
authors.lastname: Horning
authors.forename: Gareth A
authors.initials: GA
authors.lastname: Wallis
authors.forename: Jill A
authors.initials: JA
authors.lastname: Fattor
authors.forename: George A
authors.initials: GA
authors.lastname: Brooks
mesh_terms: D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005934:Glucagon / Q000097:blood; D005943:Gluconeogenesis / Q000502:physiology*; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism; D000078790:Insulin Secretion; D019344:Lactic Acid / Q000097:blood; D008875:Middle Aged; D010101:Oxygen Consumption; D010809:Physical Fitness / Q000502:physiology*; D017698:Postmenopause / Q000502:physiology*
chemical_list: D007328:Insulin; D019344:Lactic Acid; D005934:Glucagon; D005947:Glucose; D004837:Epinephrine