This topic is the first in a three-part series, presented by Rowheels, on the science of life in a wheelchair. Rowheels is reinventing the wheelchair with their patented reverse "pull" propulsion system, which curbs injuries associated with traditional "push" wheeling.
If you're like most people, your average day goes something like this: you get up in the morning, get dressed, drive to work, come home, have dinner, maybe watch some TV, and go to sleep at night. Whether you're in a wheelchair or not, the routine is about the same. But if you look closer, there are a lot of tiny but important differences between a day spent in a wheelchair and a day spent out of one, from the energy you need to the muscles you use.
You might think that, due to the fact that a wheelchair makes you sit all day, someone in a wheelchair would burn fewer calories than an able-bodied person. But that's not entirely true. In 2011, Scott A. Conger and David R. Bassett, Jr. compiled results from more than 250 studies to create one all-encompassing compendium of how many calories various activities burn for people in wheelchairs, which they published in Adapted Physical Activity Quarterly. It turns out that several activities take significantly more energy in a wheelchair—just getting around, for starters.
Traveling at a leisurely 2 miles per hour (around 3 kph), an able-bodied person burns 2.8 calories per kilogram of bodyweight per hour, whereas a wheelchair user burns 3.3. To put that in perspective, if you were a 150 pound (68 kilogram) adult traveling one mile at that speed, you'd burn 95 calories walking but 112 calories in a wheelchair. Getting ready in the morning also takes more out of you: someone in a wheelchair who spends 10 minutes getting dressed burns 35 calories, while an able-bodied person burns only 28 calories. Still, plenty of things are less taxing in a wheelchair. Housework like dusting, vacuuming, and making the bed all burn more calories out of a wheelchair than in one, and sports ranging from basketball to fencing do the same thing—a one-hour basketball game, for example, would burn 544 calories for someone running around but only 415 for someone wheeling across the court.
Shouldering The Burden
Think about the last time you were a tourist in another city. The morning after a long day of sightseeing, you probably felt pretty sore. Someone who did it all walking would have aches in their legs and feet, but for someone doing it in a wheelchair, the pain would be focused in their chest and shoulders. Pushing a wheelchair is so taxing on the shoulders, in fact, that according to some statistics as many as 70 percent of manual wheelchair users report having shoulder pain at some point in their lives.
According to the National Center on Health, Physical Activity and Disability (NCHPAD), pushing a wheelchair all day can overstretch your back muscles and make your chest and front-facing shoulder muscles overdeveloped. For the amount of work they do, some of those muscles are surprisingly small—a 2011 study found that although the biceps, triceps, and elbow extensors also play a role, the muscles that did the most work when pushing a wheelchair were the pectoral muscles, which are in the chest, the middle deltoid, which runs over the top of each shoulder, and the infraspinatus, a small muscle that connects from your shoulder blades to the tops of your arms. Compare the size of those muscles to the size of the quads, calves, and hamstrings people use to walk, and you start to understand why shoulder pain is so common among wheelchair users. The pushing motion required to propel a wheelchair isn't a very natural one, which is why some engineers are working on a new generation of wheelchairs that enable healthier patterns of movement.