EXERCISE MODE AND GENDER COMPARISONS OF ENERGY-EXPENDITURE AT SELF-SELECTED INTENSITIES

The purpose of this study was to compare oxygen consumption ((V) over dot O-2) and energy expenditure after 20 min of self-selected submaxim al exercise for four modes of exercise. Eighteen subjects (9 male and 9 female) first completed a test of (V) over dot O-2max during treadmi ll running. On separate days, subjects then completed 20 min submaxima l treadmill running (TR), simulated cross-country skiing (XC), cycle e rgometry (CE), and aerobic riding (AR) exercise. Total (V) over dot O- 2, and energy expenditure were significantly higher for TR than all ot her modes for both males and females (43.6 +/- 10.4, 39.1 +/- 9.7, 36. 1 +/- 7.6, 28.4 +/- 6.1 LO2, for TR, XC, CE, and AR, respectively, P < 0.0001). For males and females, heart rate was similar during TR and XC and lower during CE and AR (154.8 +/- 14.2, 152.6 +/- 13.1, 143.4 /- 14.9, and 126.2 +/- 12.0 beats min-l for TR, XC, CE, and AR, respec tively, P < 0.0001). Compared with females, males had significantly gr eater (V) over dot O-2, (P < 0.005) and energy expenditure (P < 0.004) , while females had higher heart rates (P < 0.003). Ratings of perceiv ed exertion (RPE) were not different between TR, XC, and CE, but were significantly lower during AR (13.4 +/- 1.3, 13.6 +/- 0.8, 13.2 +/- 0. 9, and 12.6 +/- 1.0 for TR, XC, CE, and AR, respectively, P < 0.003). TR elicited the greatest (V) over dot O-2 and energy expenditure durin g self-selected exercise despite an RPE similar to XC and CE. Therefor e, treadmill exercise may be the modality of choice for individuals se eking to improve cardiorespiratory endurance and expend a larger numbe r of kjoules.