I have long slender fingers. People tell me they are perfect piano playing fingers. With no musical gifts whatsoever, those fingers are wasted potential. I also have long(ish) slender toes. They are a genetic gift from my father. Beyond intense frustration when trying to buy flip-flops or the occasional post-race toe rehab, I don’t spend much time thinking about my toes. I especially don’t spend time thinking about how my toes may be negatively impacting my running. Or I didn’t, until now.
In a recently published article in the Journal of Experimental Biology, Rolian and colleagues found that a mere 20% increase in toe length over average leads to greater mechanical work in stabilizing the metatarsophalangeal joints and controlling the forward motion of the centre of mass during propulsion. They presume (but didn’t directly test) additional mechanical work translates to increased metabolic costs of locomotion. In practical terms the reduced mechanical performance and higher metabolic costs of long toes are suggestive of injury susceptibility. The authors specifically point to situations in which the toes are loaded for long periods of time – such as during a marathon. The extra forces could accelerate the onset of muscle fatigue, which tends to lead to alterations in loading (we change our biomechanics slightly so as to reduce pressure on the fatigued areas). Possible long term outcomes include metatarsal stress fractures and increased wear and tear on the tendons culminating in microtraumas and tendon failure. The latter issue, tendon stress, fatigue, and failure, has plagued me through the years. Perhaps my little piggies are to blame.
The authors place this research in the context of evolution. Short human toes (or more precisely, the phalangeal portion of the forefoot) differ from extant non-human hominoids (like chimps, gorillas, orangutans, gibbons) and earlier hominins. Presumably a set of physical and behavioural adaptations for endurance running, including short toes, were selected for over the course of human evolution. Our short-toed ancestors would have been more efficient runners, a fine skill when running was critical to survival. Poor Australopithecus, with their long lateral toes, could not forage as far or as long as their shorter-toed brethren. Modern humans with Australopithecus-like toes (approximately 40% longer than average) are similarly disadvantaged. Somehow surviving natural selection, we still face an increased risk of injury during distance running. I suppose non-running modern humans with long toes aren’t bothered much by the ends of their feet. My anthropology loving friend has awesomely dubbed my disadvantaged digits “Lucy Toes”. Those of you with more evolved Lilliputian-sized toes – rejoice, advantage one.
Epilogue: Since originally posting this article I did what any good scientist would do. I measured my toes. To my surprise, my increase over average is a mere 10% – less than the 20% found to mess up running. I’m on the search for a new evolutionary excuse for my less than elite times.
