Abstract: | Friedlander, Anne L., Gretchen A. Casazza, Michael A. Horning, Melvin J. Huie, and George A. Brooks. Training-induced alterations of glucose flux in men. J. Appl.Physiol. 82(4): 1360-1369, 1997. We examined thehypothesis that glucose flux was directly related to relative exerciseintensity both before and after a 10-wk cycle ergometer trainingprogram in 19 healthy male subjects. Two pretraining trials 45and 65% of peak O2 consumption( O2 peak)] andtwo posttraining trials (same absolute and relative intensities as 65%pretraining) were performed for 90 min of rest and 1 h of cyclingexercise. After training, subjects increased O2 peak by9.4 ± 1.4%. Pretraining, the intensity effect on glucose kinetics was evident with rates of appearance(Ra; 5.84 ± 0.23 vs. 4.73 ± 0.19 mg · kg 1 · min 1),disappearance (Rd; 5.78 ± 0.19 vs. 4.73 ± 0.19 mg · kg 1 · min 1),oxidation (Rox; 5.36 ± 0.15 vs. 3.41 ± 0.23 mg · kg 1 · min 1),and metabolic clearance (7.03 ± 0.56 vs. 5.20 ± 0.28 ml · kg 1 · min 1)of glucose being significantly greater(P 0.05) in the 65% than the 45% O2 peak trial. WhenRd was expressed as a percentage of total energy expended per minute(Rd E), there was nodifference between the 45 and 65% intensities. Training did reduceRa (4.63 ± 0.25),Rd (4.65 ± 0.24),Rox (3.77 ± 0.43), andRd E (15.30 ± 0.40 to12.85 ± 0.81) when subjects were tested at the same absolute workload (P 0.05). However, whenthey were tested at the same relative workload,Ra,Rd, andRd E were not different,although Rox was lowerposttraining (5.36 ± 0.15 vs. 4.41 ± 0.42, P 0.05). These results show1) glucose use is directly relatedto exercise intensity; 2) trainingdecreases glucose flux for a given power output;3) when expressed as relativeexercise intensity, training does not affect the magnitude of bloodglucose use during exercise; 4)training alters the pathways of glucose disposal. |