PHYSIOLOGIC RESPONSES DURING INDOOR CYCLING

decade, there has been active interest in indoor cycling (e.g., spinning) as a method of choreographed group exercise. Recent studies have suggested that exercise intensity during indoor cycling may be quite high and may transiently exceed _Vo2max. This study sought to confirm these findings, as the apparent high intensity of indoor cycling has implications for both the efficacy and the risk of indoor cycling as an exercise method. Twenty healthy female students performed an in-cremental exercise test to define _Vo2max and performed 2 videotaped indoor exercise classes lasting 45 minutes and 35 minutes. _Vo2, heart rate (HR), and rating of perceived exer-tion (RPE) were measured during the indoor cycling classes, with _Vo2 data integrated in 30-second intervals. The mean % _Vo2max during the indoor cycling classes was modest (74 6 14 % _Vo2max and 66 6 14 % _Vo2max, respectively). However, 52 % and 35 % of the time during the 45- and 35-minute classes was spent at intensities greater than the ventilatory threshold (VT). The HR response indicated that 35 % and 38 % of the session time was above the HR associated with VT. In 10 of the 40 exercise sessions, there were segments in which the momentary _Vo2 exceeded _Vo2max observed during incremental testing, and the cumulative time with exercise intensity greater than _Vo2max ranged from 0.5 to 14.0 minutes. It can be concluded that although the intensity of indoor cycling in healthy, physically active women is moderate, there are frequent observations of transient values of _Vo2 exceeding _Vo2max, and a substantial portion of the exercise bouts at intensities greater than VT. As such, the data suggest that indoor cycling must be considered a high-intensity exercise mode of exercise training, which has implications for both efficacy and risk. KEY WORDS spinning, group exercise, exercise trainin