How Much Physical Activity Do You Do?

Reprinted from PN October 2012

Researchers are developing a physical activity monitor system for wheelchair users.

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Let’s say you have a friend who loves to handcycle or run marathons.

It’s extremely likely you could follow your friend’s progress on a social network because the marathon organizers implement a radio frequency tracking technology that shows when participants cross various mile markers prior to completing the race.

Similarly, on social networks we might see status updates for runners and bikers who use pedometers or cycle computers that measure distances covered or speeds attained during a regular physical activity session.

However, research by our group at the University of Pittsburgh has shown that physical activity monitors designed for the general population don’t accurately capture the physical activity levels of wheelchair users who mainly use their upper arms to perform activities of daily living.

Making the Right Tools

An investigator tries the physical activity monitor system for wheelchair users.

To address this problem, we’re developing and testing a physical activity monitor system specifically for wheelchair users.

The system can accurately detect and track a wheelchair user’s physical activity level and provide near real-time feedback to the user via a smartphone. The information about the user’s physical activity levels is presented in terms of energy expenditure, distance traveled, and type, duration, and intensity of the physical activity.

Regular physical activity is crucial for wheelchair users as it is associated with a number of benefits such as increased aerobic capacity, muscular strength and endurance; flexibility; improved psychological well-being; and reduced risk of cardiovascular disease and other chronic conditions. In addition, research has shown overuse of upper extremities during wheelchair propulsion and transfers can lead to shoulder pain and carpal tunnel syndrome.

Therefore, in this project we’re building an activity monitor that can help wheelchair users attain an optimal physical activity level in their community settings. More accurate physical activity measurements in wheelchair users can empower them to track their own physical activity, leading to a more active and healthier lifestyle.

Getting the Data

The physical activity monitor system we are developing consists of two devices.

The first is a wheel-rotation datalogger/monitor mounted on one of the wheels that measures the distance traveled by the wheelchair user. The second is an accelerometer, worn on the arm, that tracks the user’s upper-arm movements during activities of daily living.

Both devices transmit the collected data wirelessly through Bluetooth in real time to an Android-based smartphone, which processes and analyzes the data in real time. We opted for the Bluetooth technology to ensure the physical activity monitoring system can be used with multiple types of smartphones, as most smartphones incorporate Bluetooth technology for communicating with external devices.

Currently, we’re testing the physical activity monitor system in manual wheelchair users performing various types of activities in laboratory and home environments such as resting, pushing their chair, performing arm-ergometer exercises, doing desk work, doing resistance-based activities, pushing on ramps, playing basketball and darts, doing laundry, and washing dishes.

During the testing phase, participants use the physical activity monitor system together with a gold standard device, which consists of a portable metabolic cart for measuring the breath-by-breath energy expenditure.

The data collected from the devices and the portable metabolic cart during testing is then used to develop innovative machine learning algorithms and regression equations that can detect wheelchair-related physical activities and estimate the physical activity levels.

We aim to test more than 45 participants in laboratory and home environments in order to increase the usefulness and precision of the system and the algorithms in new manual-wheelchair users. We also plan to conduct usability testing of the physical activity monitoring system by asking participants to use the technology in the laboratory and to give us suggestions on how to improve the performance and type of information that is provided as feedback on the smartphone.

Seeing the Potential

The results are promising and have the potential to change the way we track wheelchair users’ physical activity in community settings.

We’re also investigating how to integrate social networks into the physical activity monitor system so consumers can share their day-to-day physical activity achievements with friends and family members such as a group of friends motivating one another to do regular physical activity.

Additionally, researchers and clinicians can use this type of physical activity monitor to study and evaluate repetitive strain injuries related to wheelchair use, the effectiveness of exercise-based intervention programs to improve health and function, and quality of life. Future research will involve testing of this system in power-wheelchair users and people with multiple disabilities. 



This research is funded by the Department of Defense (W81XWH-10-1-0816). Shivayogi Hiremath’s work on this article was funded through the Switzer Research Fellowship (H133F110032) awarded by the National Institute on Disability and Rehabilitation Research, Department of Education. The work is also supported by the Human Engineering Research Laboratories, VA Pittsburgh Healthcare System. The contents do not represent the views of the Department of Veterans Affairs or the United States Government.

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