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 (R_a: 4.52 ± 0.25 vs. 5.53 ± 0.33 mg ⋅ kg⁻¹ ⋅ min⁻¹), disappearance (R_d: 4.46 ± 0.25 vs. 5.54 ± 0.33 mg ⋅ kg⁻¹ ⋅ min⁻¹), and oxidation (R_ox: 2.45 ± 0.16 vs. 4.35 ± 0.26 mg ⋅ kg⁻¹ ⋅ min⁻¹) of glucose being significantly greater (P ≤ 0.05) in the 65% than in the 45% trial. Training reduced R_a (4.7 ± 0.30 mg ⋅ kg⁻¹ ⋅ min⁻¹), R_d (4.69 ± 0.20 mg ⋅ kg⁻¹ ⋅ min⁻¹), and R_ox (3.54 ± 0.50 mg ⋅ kg⁻¹ ⋅ min⁻¹) at the same absolute workload (P ≤ 0.05). When subjects were tested at the same relative workload, R_a, R_d, and R_ox were not significantly different after training. However, at both workloads after training, there was a significant decrease in total carbohydrate oxidation as determined by the respiratory exchange ratio. These results show the following in young women: 1) glucose use is directly related to exercise intensity;2) training decreases glucose flux for a given power output;3) when expressed as relative exercise intensity, training does not affect the magnitude of blood glucose flux during exercise; but4) training does reduce total carbohydrate oxidation.