Bunions are generally thought to be an age-related condition, along with weight gain and muscle loss. Given the toll that decreased strength and increased body mass can have on a person's landing mechanics, it seems feasible that poor fitness may lead to bunions.
A study on age-related muscle loss conducted by Columbia University Medical Center reports that the condition, known as sarcopenia, begins to set in at age 40 and the rate of degeneration accelerates after 75.
As this occurs, people may have a tendency to shift their landing mechanics in a subconscious effort to compensate for a loss in core muscle strength and create more stability. This kind of pronation is thought to cause bunions, as it puts undue pressure on the forefoot and the metatarsophalangeal joint, located at the base of the big toe.
Aging individuals who find themselves developing bunions should consider a strength training routine. Additionally, bunion splints or orthotics may help to slow or halt the progression of a bunion or hammer toe before they lead to hindered mobility.