Is there a sex difference in accelerometer counts during walking in older adults?

Area of Science:

• Gerontology
• Epidemiology
• Biomedical Engineering

Background:

• Accelerometers are vital for assessing free-living physical activity in epidemiological research.
• Accurate activity assessment relies on equivalent accelerometer measurements between sexes at similar intensities.
• This study investigates sex-based differences in accelerometer output during standardized walking tests.

Purpose of the Study:

• To compare accelerometer count values between males and females during a 6-minute walk test.
• To determine if sex influences accelerometer-derived physical activity metrics.
• To identify potential confounding factors in physical activity measurement.

Main Methods:

• Older adults (N=319, age 78.6 ± 4.1 years) from the AGES-Reykjavik Study participated.
• Participants performed a 6-minute walk test at a self-selected fast pace wearing a hip-mounted ActiGraph GT3X accelerometer.
• Vertical axis counts per second were analyzed, with adjustments for walking speed, height, weight, BMI, waist circumference, femur length, and step length.

Main Results:

• Males walked significantly faster (7.2%) and exhibited 32.3% higher vertical axis accelerometer counts per second than females.
• Adjusting for walking speed reduced the sex difference in counts to 19.2%.
• Further adjustment for step length decreased the difference to 13.4%, indicating a persistent sex-based disparity.

Conclusions:

• Males consistently showed disproportionately higher accelerometer counts per second compared to females, even after accounting for walking speed.
• These sex-based differences in accelerometer output may confound the interpretation of free-living physical activity estimates in epidemiological studies.
• Further research is needed to refine physical activity measurement techniques to account for sex-specific biomechanical variations.