In this study, we examined a reliability of age-predicted heart rate (HR) for the 50%VO₂max 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%VO₂max 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 HR in NHT and HT+HRS (p<0.01 in both groups). But %ΔHR ((age-predicted HR–HR@DPBP)/HR@DPBP x 100) within -10%∼+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 %ΔHR 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+HRS, respectively). And the range of HR at rest with sitting position corresponding to -10%∼+10% of %ΔHR were 70∼95bpm in NHT, 71∼93bpm in HT+HRNS and 83∼102bpm in HT+HRS. 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.

The aim of this study is to elucidate the relationship between the predicted 50%VO₂max/wt (ml/kg/min) and coronary risk factors (CRFs).Seven hundred eighty six men (37.3 +/- 13.5 years old) and 1,268 women (41.5 +/- 13.6 years old) were studied. The predicted 50%VO₂max/wt was calculated by utilizing data from the continuous incremental exercise test with a stationary bicycle ergometer and the age-predicted heart rate at 50%VO₂max (=138-age/2). As CRFs, percent body fat, systolic blood pressure, diastolic blood pressure, total cholesterol, triglyceride, high density lipoprotein cholesterol, fasting blood sugar and HbA1c were measured.The age-adjusted odds ratio of having abnormal values in CRFs across quartiles of the predicted 50%VO₂max/wt (highest to lowest) were 1.00 (reference), 1.39, 2.64, and 6.78 in men, and 1.00, 1.73, 2.33 and 3.44 in women (for trend, p<0.001), respectively.This study indicated that the lower 50%VO₂max/wt resulted in the higher odds ratio of having abnormal values in CRFs among Japanese. It was also confirmed that the sub-maximal aerobic capacity was associated with CRFs.

The purpose of this study was to elucidate the relation between double product break point (DPBP) and pulse wave velocity (PWV).Two hundred three healthy Japanese females were studied (mean age; 53.5 +/- 11.7 years old). The DPBP was measured by continuous incremental exercise test with a bicycle ergometer (ML-3600, Fukuda Electronic Co. Ltd). The work rate at DPBP was converted into metabolic equivalents (METs@DPBP). The brachial-ankle PWV (baPWV) was also measured. In addition, height, weight and mean blood pressure (mBP) were measured and physical activity condition in daily life (PA) was evaluated by questionnaire.The mean METs@DPBP was 5.0 +/- 0.7 METs. The mean baPWV was 1,373 +/- 254 cm/ sec. The relation between METs@DPBP and baPWV was investigated with the use of multiple linear regression models with adjustment for affecting factors of baPWV.In this study, it was identified that there was a significantly inverse relation between METs@DPBP and baPWV (p <0.01). This finding was independent from age, height, weight, mBP and PA. Thus, there was an inverse relation between sub-maximal aerobic capacity and arterial stiffness.