Using accelerometry to classify physical activity intensity in older adults: What is the optimal wear‐site?

Abstract

Abstract This study aimed to determine the optimal accelerometer wear‐site specific cut‐points for discrimination of the sedentary time, light physical activity and moderate‐to‐vigorous physical activity (MVPA) in older adults. Twenty‐three adults (14 females) aged 55–77 years wore a GENEActiv accelerometer on their non‐dominant wrist, dominant wrist, waist and dominant ankle whilst undertaking eight, five‐minute bouts of activity: lay supine, seated reading, slow walking, medium walking, fast walking, folding laundry, sweeping and stationary cycling. VO 2 was assessed concurrently using indirect calorimetry. Receiver‐operating‐characteristic (ROC) analyses were used to derive wear‐site specific cut‐points for classifying intensity. Indirect calorimetry indicated that being lay supine and seated reading were classified as sedentary (<1.5 METs), laundry as light (1.51–2.99 METs) and sweeping, slow, medium and fast walking and cycling all classified as moderate intensity (>3 METs). Areas under ROC curves indicated that the classification of sedentary activity was good for the non‐dominant wrist and excellent for all other wear sites. Classification of MVPA was excellent for the waist and ankle, good for the waist and poor for the dominant and non‐dominant wrists. Overall, the ankle location performed better than in other locations. Ankle‐worn accelerometry appears to provide the most suitable wear‐site to discriminate between sedentary time and MVPA in older adults.