The Particulars: Most studies of motion detectors for measuring physical activity in patients with COPD have explored devices placed near the center of the body. Researchers hypothesize that a monitor worn on the wrist—similar to a watch—would be more convenient for patients during long-term measurements. However, validation studies of movement output that correspond to energy expenditures in patients with COPD are lacking for monitors worn on the wrist.
Data Breakdown: American investigators asked patients with COPD to simultaneously wear activity monitors on the waist and ipsilateral waist for at least 24 awake hours. Output from the waist site was considered the “gold standard.” Vector magnitude units (VMUs) from the wrist device that corresponded to more than 3,000 VMUs from the wrist device were determined. The average VMU from the wrist device above the 3,000 threshold was 4,953, whereas the corresponding VMU from the waist device was 951.
Take Home Pearl: Movements detected from an activity monitor worn on the wrist of patients with COPD appear to be considerably higher than those detected from a monitor worn on the waist.