A simple activity measure for use with ambulatory subjects

Area of Science:

• Biomedical Engineering
• Exercise Physiology
• Wearable Technology

Background:

• Monitoring physical activity is crucial for assessing health and well-being.
• Existing methods for measuring physical activity can be complex or intrusive.
• Ambulatory subjects require unobtrusive and reliable activity monitoring solutions.

Purpose of the Study:

• To develop and validate a simple activity measure using electromyography (EMG) from the thigh.
• To assess the performance of this measure during various physical activities.
• To compare the EMG activity measure with heart rate monitoring.

Main Methods:

• Developed a simple activity measure based on thigh EMG signals.
• Recorded EMG and heart rate during four activities: running, walking, standing, and sitting.
• Analyzed time series data within individuals using time series analysis.

Main Results:

• The EMG activity measure and heart rate showed similar time series models within individuals.
• Both measures effectively differentiated between running, walking, and non-movement.
• The activity measure did not distinguish between different postures (standing, sitting).
• The EMG activity measure was a significant predictor of heart rate variance, more so than activity type.
• Posture independently contributed to heart rate variance.

Conclusions:

• The developed thigh EMG activity measure is a simple, reliable, and valuable tool for monitoring physical activity variations in ambulatory subjects.
• This measure shows strong correlation with heart rate and can differentiate key activity levels.
• While not distinguishing postures, it offers a significant advancement in unobtrusive physical activity monitoring.