VO2max is the main measure of fitness. The higher your VO2max, the fitter and healthier you are.
A study by Western Colorado University split participants into 2 groups. Group 1 did 3x short Reduced Exertion HIIT (REHIT) workouts on a CAROL Bike each week; while Group 2 did 5x 30-minutes of moderate-intensity continuous training.
In just 8 weeks, the CAROL Bike group increased their VO2max by 12.3%, the other group by only 6.9%. That’s close to double the improvement—in 90% less time.
Read the full study here.