Evaluation of ACSM Guidelines on Prescribing Exercise Intensity for “Quite Unfit”

Abstract

0062 In 1998, the ACSM revised its guidelines for prescribing the intensity of aerobic exercise, adding that one could lower the intensity to 40% VO2 reserve (VO2R) for “quite Unfit” people. PURPOSE: To investigate the relationship between %VO2R and the ventilatory threshold (vt) in 442 initially sedentary individuals (ages 17 to 65). METHODS: Each participant completed 2 graded cycle tests to exhaustion before and after 20 weeks of training. VO2 and heart rate data were collected at the end of each stage. The absolute (ml•kg−1•min−1) and relative (%VO2R) values for VO2vt were determined for each subject. RESULTS: The average absolute values for VO2vt were about 10–14 ml•kg−1•min−1 for 183 subjects whose VO2 max was 15.4–29.9 ml•kg−1•min−1. This is similar to the value of 15 ml•kg−1•min−1 that Shephard states is associated with activities of daily living. The range of relative values for the VO2vt of these subjects was 42–83% VO2R, with most subjects between 50% and 70% VO2R. Intensities below VO2vt are generally aerobic in nature and can be done without much distress. It should be noted that these subjects began the training program by exercising for 30 minutes at the heart rate associated with 50% VO2 max and had few problems. CONCLUSION: Because “quite Unfit” sedentary subjects are already doing enough activity in their daily lives to maintain a VO2vt at levels that are generally greater than 50% VO2R, it is not necessary to reduce the prescribed intensity to 40% VO2R, as recommended by the ACSM. Supported by multiple grants from NIH-NHLBI.