guarantee
Technical Information
Manual wheelchairs have evolved to be simple, lightweight, and maneuverable. However, the majority of 1.4 million manual wheelchair users in the United States eventually suffer from Repetitive Strain Injuries (RSI) and related injuries of the shoulders, elbows, and wrists due to the long term effects of the awkward biomechanics of manual wheelchair pushrim use. This is due to factors such as:
- unidirectional propulsion stroke leading to unbalanced muscle and tendon development, and poor posture
- high peak propulsion force required due to the brief window of optimal arm geometry
- reaction torque due to the direction of the propulsion force not passing through the shoulder - the body must continually stabilize the shoulder, leading to muscle, tendon, and ligament strain, particularly the rotator cuff
- propulsion force direction not effectively utilizing major muscle groups such as the chest
- repeated grasping and releasing of the pushrim required and wrist rotating in an awkward direction, leading to Carpel Tunnel Syndrome
These injuries force many users to transition prematurely into power wheelchairs. Disadvantages of power wheelchairs use include high cost, reduced transportability, and, most importantly, the loss of therapeutic physical exertion. The health problems of a sedentary lifestyle result.
Published studies have consistently shown that that lever and handcrank propulsion are significantly more biomechanically efficient than manual pushrim propulsion and reduce the magnitude of injury mechanisms that result in RSI. Advantages include:
- propulsion stroke in both directions, more fully utilizing large muscle groups resulting in greater power output and efficiency
- more continuous force application, resulting in lower peak force and again greater power output and propulsion efficiency
- an application of force more in alignment with the shoulder, minimizing torque on the shoulder and consequently the stabilization force required
- continuous grasping of the handle with minimal to no wrist rotation
However, no lever design to date has had significant success in the market, and the handcycles that are available are expensive and do not attach easily to most wheelchairs. Fortunately, Rio Mobility has the solution! Please view our product pages for more information.
