We examined the effects of exercise and endurance training on glucose flux and energy substrate partitioning (%CHO/%fat) during rest and exercise in postmenopausal women. Ten sedentary, but healthy women (55 ± 1 yr) subjects completed 12 weeks of endurance exercise training on a cycle ergometer [5 days/wk, 1 h/day, 65% peak oxygen consumption (VO2peak)]. Glucose flux was determined by primed-continuous infusion of [6,6-2H]glucose (D2-Glucose) and whole-body energy substrate oxidation was determined by indirect calorimetry during 90 minutes of rest and 60 min of cycle ergometer exercise during one pre-training exercise trial [65% VO2peak (PRE)] and two post-training exercise trials [the power output that elicited 65% pre-training VO2peak (ABT) and 65% post-training VO2peak (RLT)]. After training, VO2peak increased by 16.3 ± 3.9% and there was a 19bpm decrease in resting heart rate (p < 0.05). Exercise heart rate, mean arterial pressure, pulmonary minute ventilation, plasma [epinephrine] and plasma [glucagon] were lower during ABT and lactate was lower at ABT and RLT (p < 0.05). Endurance training decreased the energy derived from carbohydrate by 9.61% and increased the energy from lipid by 9.20% during ABT, but not RLT (p < 0.05). Whole body glucose Ra decreased post-training during exercise at a given power output (4.58 ± 0.39 mg•kg-1•min -1 during ABT compared to 5.21 ± 0.48 mg•kg-1•min -1 PRE, but not RLT (5.85 ± 0.36 mg•kg-1•min -1). The training-induced reductions in glucose Ra (12%) and Rd (-11%) during ABT were similar to those previously seen in similarly treated young women (Friedlander AL, Casazza GA, Horning MA, Huie MJ, Piacenini MF, Trimmer JK, Brooks GA. Training-induced alterations of carbohydrate metabolism in women: women respond differently from men. J Appl Physiol 85: 1175-1186, 1998.). Changes in glucose flux and substrate partitioning during exercise were accomplished without changes in body weight or body composition. We conclude that in healthy postmenopausal women, endurance training results in many of the classic cardiopulmonary and metabolic training effects as seen in young women without the necessity to reduce body weight or alter body composition.
|Advisor:||Brooks, George A.|
|School:||University of California, Berkeley|
|School Location:||United States -- California|
|Source:||DAI-B 70/11, Dissertation Abstracts International|
|Keywords:||Body weight, Glucose, Postmenopausal|
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