COMPARISON OF HEART RATE AT DOUBLE PRODUCT BREAK POINT TO AGE-PREDICTED HEART RATE AT 50%VO2max

In this study, we examined a reliability of age-predicted heart rate (HR) for the 50%VO(2)max which is widely used during a training program for health promotion as compared to HR at the double product break point (DPBP). Two hundred fifty six non-hypertensive subjects (NHT), and 49 hypertensive ones under medication (HT) were studied. HT subjects were divided into two subgroups based on antihypertensive medications, ones with HR non-suppression agents (HT+HRNS) and the other with HR suppression agents (HT+HRS). DPBP was measured with the use of an incremental exercise test, and HR at DPBP (HR@DPBP) was determined. Age-predicted HR for the 50%VO(2)max intensity of exercise was calculated with the following formula; HR=138-age/2. Measurable rate of DPBP and HR@DPBP in NHT, HT+HRNS and HT+HRS were 93.8% and 120 +/- 14bpm, 92.7% and 104 +/- 12bpm, 78.5% and 94 +/- 16bpm, respectively. There were significant differences in HR@DPBP and age-predicted FIR in NHT and HT+HRS (p<0.01 in both groups). But %Delta HR ((age-predicted HR-HR@DPBP)/HR@DPBP x 100) within -10%similar to+10% in NHT, HT+HRNS and HT+HRS were 68%, 58% and 14%, respectively. This might be due to HR at rest with sitting position that was significantly correlated to %Delta HR in all groups (r=-0.604, p<0.001 in NHT, r=-0.689, p<0.001 in HT+HRNS and r=-0.761, p<0.05 in HT+FIRS, respectively). And the range of HR at rest with sitting position corresponding to -10%similar to+10% of %Delta HR were 70 similar to 95bpm in NHT, 71 similar to 93bpm in HT+HRNS and 83 similar to 102bpm in HT+FIRS. In addition, this study indicated that DPBP could be measured even under antihypertensive medication that might affect DPBP measurement. In conclusion, we demonstrated that HR at DPBP and age-predicted HR were similar among 58-68% of NHT and HT+HRNS. And the range of HR at rest with sitting position to ensure reliability of age-predicted HR was elucidated. (Jpn. J. Phys. Fitness Sports Med. 2010, 59 : 513 similar to 520)