Myocellular triacylglycerol breakdown in females but not in males during exercise.

The resting content and use of myocellular triacylglycerol (MCTG) during 90 min of submaximal exercise [60% of peak oxygen uptake (VO(2 peak))] were studied in 21 eumenorrheic female and 21 male subjects at different training levels [untrained (UT), moderately trained (MT), and endurance trained (END)]. Males and females were matched according to their VO(2 peak) expressed relative to lean body mass, physical activity level, and training history. All subjects ingested the same controlled diet for 8 days, and all females were tested in the midfollicular phase of the menstrual cycle.

Gender differences in substrate utilization during submaximal exercise in endurance-trained subjects.

Substrate utilization across the leg during 90 min of bicycle exercise at 58% of peak oxygen uptake (VO(2 peak)) was studied in seven endurance-trained males and seven endurance-trained, eumenorrheic females by applying arteriovenous catheterization, stable isotopes, and muscle biopsies. The female and male groups were matched according to VO(2 peak) per kilogram of lean body mass, physical activity level, and training history of the subjects. All subjects consumed the same diet, well controlled in terms of nutrient composition as well as energy content, for 8 days preceding the experiment, and all females were tested in the midfollicular phase of the menstrual cycle.