Training-induced alterations of carbohydrate metabolism in women: women respond differently from men

We examined the hypothesis that glucose flux was directly related to relative exercise intensity both before and after a 12-wk cycle ergometer training program [5 days/wk, 1-h duration, 75% peak O2 consumption (V˙o 2 peak)] in healthy female subjects (n = 17; age 23.8 ± 2.0 yr). Two pretraining trials (45 and 65% of V˙o 2 peak) and two posttraining trials [same absolute workload (65% of oldV˙o 2 peak) and same relative workload (65% of newV˙o 2 peak)] were performed on nine subjects by using a primed-continuous infusion of [1-13C]- and [6,6-2H]glucose. Eight additional subjects were studied by using [6,6-2H]glucose. Subjects were studied postabsorption for 90 min of rest and 1 h of cycling exercise. After training, subjects increasedV˙o 2 peak by 25.2 ± 2.4%. Pretraining, the intensity effect on glucose kinetics was evident between 45 and 65% ofV˙o 2 peak with rates of appearance (Ra: 4.52 ± 0.25 vs. 5.53 ± 0.33 mg ⋅ kg−1 ⋅ min−1), disappearance (Rd: 4.46 ± 0.25 vs. 5.54 ± 0.33 mg ⋅ kg−1 ⋅ min−1), and oxi...