CSUN researchers found each subject's heart rates to be between 75 and 96% of age-predicted maximum heart rate, with the majority of the time spent at the higher end of the range.
During the active recovery periods, the ideal intensity level is 50% age-predicted maximum heart rate. Not only does this level maintain blood perfusion through the heart and liver to facilitate the removal of lactic acid, but allows for slow and controlled movements that insures proper form, speed and isolation during the body conditioning work.