RESUMEN
In this study, we examined a reliability of age-predicted heart rate (HR) for the 50%VO<sub>2</sub>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<sub>2</sub>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 HR in NHT and HT+HRS (<i>p</i><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, <i>p</i><0.001 in NHT, r=-0.689, <i>p</i><0.001 in HT+HRNS and r=-0.761, <i>p</i><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.
RESUMEN
The purpose of this study was to determine the influence of a 6-month unsupervised, flexible and fairly light intensity walking program on endurance fitness, strength, lipids and lipoproteins and bone health in a group of middle-aged sedentary women. Six pre-menopausal and 8 post-menopausal women, aged 54 yr, served as the walk training group (W) and 9 women (2 post-menopausal), aged 49yr, served as controls (C) . W walked an average of 10, 000 steps per day for 6 months, which included an average of 5, 000 steps of brisk walking for 30 min, 4 to 5 days per week. Workloads, heart rates and double-product break point (during incremental maximal ergometer exercise), body weight and %fat, serum lipids, leg strength and bone density (by ultrasound) and induces of bone metabolism were measured at baseline and after 3 and 6 months. Walk training in W resulted in a significant improvement in maximal workload during the exercise test compared with C. Double product break point in W during exercise significantly shifted towards higher workloads and resting heart rate was reduced. Isokinetic muscular strength of leg extensors and abdominal muscular endurance measured by situps were also significantly increased in W. Estimated calcaneal bone density showed a tendency to increase after 6 months of training in W. Indicators of bone resorption and growth remained unchanged. Changes in serum lipids and lipoproteins were also favorable, but not significant. In conclusion, these results show that a flexible and self-regulated walking program is sufficient to elicit improvements in cardiovascular endurance, aerobic capacity measured by DPBP and strength of leg and abdominal muscles. Bone strength and serum lipids were not clearly improved after 6 months with this walking program. If training time were extended to 12 months, significant improvements in these measures can be expected because tendencies toward improvements were observed.