Biomechanics of distance running

Abstract

Running speed is dictated by an athlete's step length and cadence, although step length is more important in differentiating between faster and slower runners, and reduces more with fatigue.Being able to increase cadence, however, is often the deciding factor in sprint finishes.• Of the different components that make up step length, the distance the body travels during flight is the most important.An athlete's flight distance is determined by upward and forward impulse in late stance, which usually decrease with fatigue because of reduced leg stiffness and tolerance to repeated stretch loads.• Middle-distance runners are more likely to land on the forefoot or midfoot at first contact, whereas marathon runners tend to land on the heel.There are potential performance benefits to landing near the front of the foot through the stretch-shortening cycle and shorter contact times, although these apply less in longer events.• There are small gains to be made from following rival runners in terms of air resistance, although having air moving around the body for cooling is important in hot conditions.Running uphill is unsurprisingly more energy costly than running on flat courses, but running downhill can risk injury because of the increased load on the knee, hip, and shin muscles.• Running of soft surfaces, such as in cross country running, is more difficult than on roads because the non-compliant nature of the surface reduces the effectiveness of the stretchshortening cycle, and is more energy costly because of an increase in leg stiffness to accommodate a reduction in stability.