New Predictor of Running Performance?

An interesting article recently published by a Swiss group finds an interesting new predictor for success in endurance running: the circumference of your upper arm. The researchers in this study measured runners participating in the "Deutschlandlauf" (a race covering 1200 km in 19 days!) for a broad variety of factors including age, body mass index (BMI), height, weight, skinfold measurements, and measurements of other anthropometric factors (such as calf and thigh circumference measurement). Amazingly, NONE of these correlated with performance in the event itself EXCEPT for measurement of the circumference of the upper arm. Obviously, a major message from this research is the idea that carrying around ANY mass (muscle or fat) not related to bipedal locomotion appears detrimental to running. The upper arm's relevance as a measuring point, though, is something of a mystery, as there can be great discrepancy in arm circumference, even among lean individuals. It would be interesting to look at the people who do well in local races of varying lengths and see if the correlation holds to shorter distances (say, less than 50 km or so for the more mortal of us).

Sadly, the full article isn't available online, but I've posted a link to the abstract.