Physiological responses during an incremental exercise test performed on underwater stationary bike

Purpose: Cycling underwater is a low impact physical activity that has became popular workout due to capability to enhance physical fitness. The aim of this study was to determine the relationship between pedal cadence with heart rate (HR) and oxygen uptake (VO2) during incremental exercise test in a novel adjustable resistance bike underwater. Methods: Fifteen participants completed three incremental cycling tests in a random order. Each test began at 50 revolutions per minute (RPM) and increased 3 RPM every minute until volitional exhaustion. The bike has the unique ability to manipulate the frontal surface area (FSA) of the blades providing three different resistance settings for the same RPM (FSA1 = 500 cm2, FSA2 = 580 cm2, and FSA3 = 660 cm2). Results: The findings indicated a strong linear relationship between RPM vs. %VO2peak and RPM vs. %HRpeak in all FSA conditions (r = 0.98–0.99). In addition, the results showed a significant lower peak cadence for the FSA3 setting compared to the other conditions (p < 0.05). However, there were no differences in maximal physiological responses between all frontal area conditions. Conclusions: Therefore, the developed exercise prescription on the novel stationary bike needs to consider the FSA of the blades due to differences found in the predictive values of VO2 and HR for the same pedal cadence. © 2016, Springer-Verlag Italia.