Veterans Affairs

Ergonomic, customizable hand pedal

New design creates an efficient delivery of energy from the user to the drive gear for better hand crank performance on push bikes, upper body exercise machines, and other hand powered devices

Medical & Biotechnology

Research scientists at the U.S. Department of Veterans Affairs have recently invented a hand pedal to be used with hand-pedaled wheelchairs, upper body exercise equipment, and other hand powered devices. The patent-pending technology is available via patent license agreement to companies that would make, use, or sell it commercially.

Fig. 1. Expanded view of the modular highly customizable hand pedal.

Fig. 2. Prototypes mounted on hand pedal cycles.

Hand bicycles are tricycles that people with disabilities pedal with their arms by grasping hand pedals connected to a crankset. The crankset typically uses a chain drive to power one or more of the wheels upon rotation of the crankset by the user. Hand bicycles are in widespread use for exercise as well as in competitive racing sports similar to bicycling.

These hand pedals have significant shortcomings. For example, the spindle, which attaches the hand pedal to the crankset, is attached to the middle of the pedal. This configuration forces the user to use a weaker open grasp technique which is prone to causing blisters. And, with the spindle attached to the middle of the hand pedal, it is difficult to align the center of rotation of the hand pedal with the forearm and the center of the wrist as the crank is turned. As a result, off axes loading of the wrist and radial/ulnar deviation occur, thereby increasing the risk of carpal tunnel syndrome, fatigue and pain. Furthermore, the pedals do not allow for adjustment of the pedal position to align with the center of the shoulder for a biomechanically sound pedaling position.

In response to the above, the VA has developed an ergonomic and modular, highly-customizable hand-pedal for hand-bikes, hand-cycles, arm-ergometers, exercise equipment, strengthening devices, exergaming interfaces, and biophysical measurement devices. The fully adjustable features are shown in figure 1. The adjustments are important for ensuring that the pedal is anatomically aligned with the shoulder and the center of the wrist. The spindle rotational axis is aligned with the center of wrist to allow optimal transfer of force with minimal movement. The result is an efficient and safe pedaling stroke for all abilities and activities.

 

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