Rationale:
Maximal HR (HRmax) is critical for exercise prescription. HRmax is usually predicted using age based equations, 220-age being the most common. The accuracy of 220-age is suspect, with SEE ~12 bpm. Even contemporary age based equations (averaging 210-0.70*age) have SEE of 6-13. This inaccuracy can lead to significant errors in exercise prescription.
Objectives:
This study was designed to test strategies for predicting HRmax based on the HR response during submaximal exercise.
Methodology:
Healthy volunteers (age 22-53) (n = 28) performed maximal treadmill exercise to define HRmax. They also performed submaximal exercise tests based on Edwards' Heart Zones approach. These submaximal tests were: 5-min Walk Test, 1-min Chair Test, 3-min Step Test, Talk Test, 2-min 10 Beat Test, 2 by 4-min Test, and Easy-Moderate-Hard Test. Each test had unique instructions and included a self-assessed fitness level to predict HRmax.
Results:
There were significant (P <.05) differences between measured HRmax (189 +/- 12) and predicted HRmax from: 2 x 4-min test (214 +/- 13), Talk Test (199 +/- 11), Step Test (202 +/- 20), Walk Test (176 +/- 22) and 2-min 10 Beat Test (214 +/- 8). Linear regression demonstrated that predicted HRmax from all submaximal exercise tests was poorly related to HRmax (R2 = 0.04-0.56). If self assessed fitness level was ignored, the highest HR during the submaximal tests was better in predicting HRmax (R2 = 0.01-0.66). The best predictors of HRmax were HR the last time speech was comfortable (R2 = 0.26; SEE = 12), HR at RPE = 5 (hard) (R2 = 0.34; SEE = 9), and HR at the time speech became impossible (R2 = 0.66; SEE = 7). Attempts to use the regression of RPE and HR during the incremental exercise test demonstrated that HR @ RPE of 5 (hard) was best at predicting HRmax (R2 = 0.21; SEE = 10).
Conclusion:
HRmax is difficult to predict based on results of submaximal exercise tests. The gain in predictive accuracy over an optimized age prediction is not likely to be of practical significance.