Objective As an indicator of exercise intensity, heart rate can be measured in a timely manner using wrist-worn devices. No study has attempted to estimate a target exercise intensity using wearable devices. The objective of the study was to evaluate the validity of prescribing exercise intensity using wrist-worn devices. Methods Thirty healthy subjects completed a maximal cardiopulmonary exercise test. Their heart rates were recorded using an electrocardiogram and two devices—Apple Watch Series 6 and Garmin Forerunner 945. Exercise intensity with the target heart rate was defined as resting heart rate + (maximal heart rate − resting heart rate) * n% ( n%: 40–60% for moderate-intensity exercise and 60–89% for vigorous-intensity exercise). Heart rate was analyzed at the lower and upper limits of each exercise intensity (HR40, HR60, and HR89). The mean absolute percentage error and concordance correlation coefficient were calculated, and Bland–Altman plots and scatterplots were constructed. Results Both devices showed a low mean absolute error (1.16–1.48 bpm for Apple and 1.35–2.25 for Garmin) and mean absolute percentage error (<1% for Apple and 1.16–1.39% for Garmin) in all intensities. A substantial correlation with electrocardiogram-measured heart rate was observed for moderate to vigorous intensity with concordance correlation coefficient > 0.95 for both devices, except that Garmin showed moderate correlation at the upper limit of vigorous activity with concordance correlation coefficient = 0.936. Moreover, Bland–Altman plots and scatterplots demonstrated a strong correlation without systematic error when the values obtained via the two devices were compared with electrocardiogram measurements. Conclusions Our findings indicate the high validity of exercise prescriptions based on the heart rate measured by the two devices. Additional research should explore other populations to confirm these findings.

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Background: There has been a reported reduction in the incidence of amputation, but it is unclear whether the number of amputations has decreased in the elderly, a cohort that typically has the largest proportion of amputees. Objectives: To investigate the incidence proportion and time trends of amputation in patients aged $ 65 years in Taiwan. Study design: A retrospective cohort study from a large national database. Methods: The records of patients who underwent an amputation were collected from a nationally representative sample of 1,000,000 enrollees of Taiwan's National Health Insurance program during 1996-2013. The patients were divided into four age groups: #64, 65-74, 75-84, and $85 years. Joinpoint regression was performed with adjustment for age and sex to identify changes in incidence proportion by year. Results: During the 18 years, the incidence of upper and lower limb amputation decreased significantly in the total population, with the average annual percentage change (AAPC) of 26.1 and 21.8, respectively. However, in the elderly population over 65 years, the incidence did not decrease significantly for upper minor amputation, lower minor amputation, and major amputation with the AAPC of 21.1, 20.1, and 20.4, respectively. Although not significant, the incidence of major and minor lower limb amputation in the population over 85 years old showed an increasing trend, with the AAPC of 1.2 and 3.2, respectively. Conclusion: During the study period, although the incidence of amputation of the overall population decreased in Taiwan, this trend was not simultaneously observed in the elderly and hence, it should not be ignored.