Meeting Abstract
P3.68 Tuesday, Jan. 6 Function and fatigue: Changes over a marathon race in recreational athletes. BERTRAM, J.E.A*; SZARKO, M.J.; PREBEAU-MENEZES, L; Univ. of Calgary, Calgary; Univ. of Calgary, Calgary; Univ. of Calgary, Calgary jbertram@ucalgary.ca
Even compared with many cursorial mammals, fit humans display a remarkable ability to run long distances at moderately high speeds. This suggests long distance running may be an adaptive feature of humans. Although substantial research has been conducted on running mechanics and physiology, the process of fatigue and the functional response to extreme endurance is not well understood. As a recognized test of endurance, the marathon has become a goal of many non-elite, recreational running enthusiasts. We exploited the opportunity to analyze the changes in gait of a range of individuals participating in a community marathon race using a series of instrumented force platforms that could monitor features of gait pre-race, mid-race (19 km) and near the end of the race (36 km). Not surprisingly, we found that the most successful runners (lowest finishing times) were able to maintain running speed for the duration of the race with very little change in speed or gait. Those with slower race times began the race at roughly similar pace to the faster runners, but this slowed as the race progressed, indicating the effects of fatigue. Interestingly, in fatigue speed decrease results from a decrease in stride length not stride frequency. This is contrary to most lab studies of fatigue; however, these are generally conducted using a constant speed protocol (treadmill) in which the subjects gait options are necessarily constrained. Shorter steps at a given frequency alter the geometry of the contact with the substrate, which, combined, with the elastic recovery of the running step, limits the required work performed by the leg. Well-trained runners show the same step length change with increase in age over their running career as the younger recreational runners show with progress over the course of a single race.
