Measuring Physical Activity in Spinal Cord Injury Using Wrist-Worn Accelerometers

Area of Science:

• Rehabilitation Medicine
• Biomedical Engineering
• Physical Therapy

Background:

• Accurate measurement of physical activity is crucial for individuals with spinal cord injury (SCI) to monitor health and recovery.
• Existing activity monitors need validation for this specific population.
• Understanding the reliability and validity of devices like Actiwatch Score and PRO-Diary is essential.

Purpose of the Study:

• To assess the interunit agreement between the Actiwatch Score and PRO-Diary.
• To evaluate the construct validity of these two activity monitors.
• To determine their suitability for use in individuals with and without spinal cord injury.

Main Methods:

• Thirty-eight participants (19 with SCI, 19 controls) participated in the study.
• Participants wore both Actiwatch Score and PRO-Diary devices.
• Activity levels were measured during tasks of varying physical intensity, with statistical analyses including t tests, intraclass correlations, and Bland-Altman plots.

Main Results:

• Both monitors accurately detected increasing physical activity with higher intensity tasks.
• Participants with SCI showed comparable activity counts to controls, except during walking-wheeling tasks.
• High interunit agreement was observed between the Actiwatch Score and PRO-Diary (ICC = .78–.97).

Conclusions:

• The Actiwatch Score and PRO-Diary exhibit good construct validity for assessing physical activity across diverse activities.
• Both devices demonstrate high agreement, making them reliable tools.
• Either monitor can be appropriately used to study physical activity patterns in individuals with spinal cord injury.