Evaluating Walking Intensity with Hip-Worn Accelerometers in Elders.

Area of Science:

• Gerontology
• Exercise Physiology
• Biomedical Engineering

Background:

• Objective physical activity assessment is crucial for older adults.
• Accelerometers are commonly used to measure physical activity.
• Metabolic effort (METs) provides a measure of exercise intensity.

Purpose of the Study:

• To examine the association between accelerometer activity counts and metabolic effort (METs) in older adults.
• To determine if walking pace influences this association.
• To investigate potential misclassification of physical activity in older adults.

Main Methods:

• Forty-five older adults (mean age 76.3 years) performed a 400-m walk at usual and rapid paces.
• Pulmonary gas exchange was measured using a portable metabolic unit.
• Hip-worn accelerometers recorded activity counts; participants were classified as slow or fast walkers.

Main Results:

• Activity counts were significantly associated with METs during rapid walking (r=0.62, P<0.01), but not usual-pace walking (r=0.24, P=0.11).
• Slow walkers exhibited half the activity counts of fast walkers across conditions (P<0.01).
• Despite lower counts, slow walkers achieved 82-90% of the METs of fast walkers.

Conclusions:

• Accelerometer data may misclassify the physical activity levels of functionally impaired older adults with slow walking speeds.
• Current accelerometer thresholds may not accurately reflect metabolic effort in slower-paced older adults.
• Further research is needed to refine activity assessment methods for diverse older adult populations.