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Purpose: This study aimed to determine and compare the accuracy of different activity monitors in assessing intermittent outdoor walking in both healthy and clinical populations through the development and validation of processing methodologies., Methods: In study 1, an automated algorithm was implemented and tested for the detection of short (≤1 min) walking and stopping bouts during prescribed walking protocols performed by healthy subjects in environments with low and high levels of obstruction. The following parameters obtained from activity monitors were tested, with different recording epochs0.1s/0.033s/1s/3s/10s and wearing locationsscapula/hip/wrist/ankle: GlobalSat DG100 (GS) and Qstarz BT-Q1000XT/-Q1000eX (QS) speed; ActiGraph wGT3X+ (AG) vector magnitude (VM) raw data, VM counts, and steps; and StepWatch3 (SW) steps. Furthermore, linear mixed models were developed to estimate walking speeds and distances from the monitors parameters. Study 2 validated the performance of the activity monitors and processing methodologies in a clinical population showing profile of intermittent walking due to functional limitations during outdoor walking sessions., Results: In study 1, GS1s, scapula, QS1s, scapula/wrist speed, and AG0.033s, hip VM raw data provided the highest bout detection rates (>96.7%) and the lowest root mean square errors in speed (≤0.4 km·h-1) and distance (<18 m) estimation. Using SW3s, ankle steps, the root mean square error for walking/stopping duration estimation reached 13.6 min using proprietary software and 0.98 min using our algorithm (total recording duration, 282 min). In study 2, using AG0.033s, hip VM raw data, the bout detection rate (95% confidence interval) reached 100% (99%-100%), and the mean (SD) absolute percentage errors in speed and distance estimation were 9% (6.6%) and 12.5% (7.9%), respectively., Conclusions: GPS receivers and AG demonstrated high performance in assessing intermittent outdoor walking in both healthy and clinical populations., (Copyright © 2021 by the American College of Sports Medicine.)

Peripheral artery disease (PAD) is a highly prevalent disease diagnosed by the use of ankle-brachial index (ABI) at rest. In some clinical conditions (diabetes, renal insufficiency, advanced age), ABI can be falsely normal and other tests are required for the PAD diagnosis (American Heart Association statement). This study was conducted to determine the accuracy of exercise transcutaneous oxygen pressure measurement (exercise-TcPo2) in detection of arterial stenosis ≥50% using computed tomography angiography (CTA) as the gold standard.We retrospectively analyzed consecutive patients referred to our vascular unit (University Hospital, Rennes, France) for exercise-TcPo2 testing from 2014 to 2015. All included patients had a CTA performed within 3 months of the exercise-TcPo2 test. Exercise-TcPo2 was performed on treadmill (10% slope; 2 mph speed). We calculated the Delta from Resting Oxygen Pressure (DROP) index (expressed in mm Hg) at the proximal and distal levels. Two blinded physicians performed stenosis quantification on CTA. The receiver operating characteristic (ROC) curve was used to define a cutoff point to detect arterial stenosis ≥50%, stenosis ≥60%, and stenosis ≥70%.A total of 34 patients (mean age 64 ± 2 years old; 74% men) were analyzed. The highest areas under the curve (AUC) were found for 60% stenosis at both proximal and distal levels. For stenosis ≥50%, sensitivity and specificity of proximal minimal DROP were 80.9% [67.1-89.7], 81.0% [59.3-92.7] respectively. For stenosis ≥50%, sensitivity and specificity of distal minimal DROP were 73.2% [60.3-83.1], 83.3% [53.8-96.2], respectively. For stenosis ≥60%, sensitivity and specificity of proximal minimal DROP were 82.5% [67.6-91.5] and 85.7% [67.7-94.8] respectively. For stenosis ≥60%, sensitivity and specificity of distal minimal DROP were 80.4% [67.3-89.1] and 88.2% [64.2-97.7], respectively. For stenosis ≥70%, sensitivity and specificity of proximal minimal DROP were 85.7% [67.7-94.8] and 75.0% [59.6-85.9] respectively. For stenosis ≥70%, sensitivity and specificity of distal minimal DROP were 86.0% [72.2-93.7] and 76.0% [56.1-88.7], respectively.Exercise-TcPo2 using a proximal minimal DROP value ≤-15 mm Hg or a distal minimal DROP value ≤-16 mm Hg is accurate to diagnose arterial stenosis especially stenosis ≥60% on the lower limbs. Exercise-TcPo2 is safe and noninvasive test that might be used in second line for PAD diagnosis., Competing Interests: The authors have no conflicts of interest to disclose.