Energy cost of using Hydroforce equipment and a comparison of heart rate and subjective responses to land cycling

This study determined the energy cost of exercising on the Hydroforce Cycle and Slider and compared heart rate (HR) and subjective ratings of perceived exertion (RPE) during stationary cycling in water and on land at the same oxygen consumption (VO₂). Ten trained cyclists (VO₂max > 50 ml/kg/min) participated in this study. Eight of the ten subjects participated in the energy cost of the Hydroforce Cycle, Slider, and comparison portion of the study. To determine the energy cost of each piece of equipment, 2 subjects rode at each of the selected cadences and throughout the range of selected levels. Open circuit spirometry was used to determine caloric cost. The physiological and subjective parameters measured included: HR, respiratory exchange ratio (RER), minute ventilation (VE), VO₂, and RPE. The VO₂ elicited by the available range of levels on the Hydroforce Cycle and Slider were 0.87 L/min - 2.38 L/min and 0.82 L/min - 2.09 L/min, respectively. Eight subjects were then asked to ride at 65 rpm on level 3 of the Hydroforce Cycle. On a separate day they rode a Monark cycle ergometer on land at 65 rpm and at a resistance that would elicit the same VO₂ again using the open circuit spirometry technique for gas collection and analysis. HR and RPE responses measured during stationary cycling in water were compared to those on land and showed no significant difference for either variable. It was concluded that exercise on the Hydroforce Equipment elicits an energy expenditure between 235-700 kcals/hr and may be performed by people of both high and low fitness levels. It was also concluded that stationary cycling in water and on land elicit similar physiological and subjective responses.