Propulsion of manual wheelchairs improves a user's cardiovascular fitness and upper body strength. As one would expect, a user's strength and stamina typically diminish over time. Of necessity, these users must transition to a power wheelchair or be pushed about in a manual wheelchair by a caregiver. Frail elderly and persons in the later stages of progressive disabilities typify such users. Extending the period during which these user's can self-propel would provide important health and independence benefits.