PREDICTING MAX HR AND THE HR-VO2 RELATIONSHIP FOR EXERCISE PRESCRIPTION IN OBESITY

This research derived regression equations for predicting maximal hear t rate (MHR) and examined the relationship between relative oxygen con sumption (VO2) and heart rate (HR) in obese (N 86, body fat > 30%, hyd rostatic weighing) compared with normal-weight (N = 51, body fat less- than-or-equal-to 30%) adults. Simultaneous measurements of HR and VO2 were recorded at rest and every minute during a maximal graded exercis e test. When MHR was regressed on age, two distinct equations for the obese and normalweights were generated. The relationship between %MHR and %max VO2 was similar between groups (r = 0.83, obese; r = 0.87 nor malweights). Likewise, when %max VO2 was regressed on %max heart rate range similar equations were derived for the obese (r = 0.81) and norm alweights (r = 0.84). Correlation between Karvonen's predicted HR at a submaximal VO2 and the true HR at that VO2 Was 0.88, regardless of ad iposity. These data indicate that when predicting MHR in normalweights the equation 220 - Age can be used, but for obese individuals the equ ation 200 - 0.5 x Age is more accurate; each having 12 as a standard e rror of estimate. Once MHR is determined, either the straight percenta ge technique or Karvonen's method would be appropriate for prescribing exercise intensity for both populations.