The actiology of and risk factors for EAMC are not known. The aim of this study was to identify risk factors associated with (EAMC) in marathon runners. 1383 marathon (42km) runners responded to a questionnaire designed to identify risk factors for EAMC. Responders were divided into a cramping (C, n=536) and a non-cramping (NC, n=847) group according to their past history of EAMC. In the C group, EAMC during running (as a% of crampers) was associated with; racing (85%), onset of cramping after 30 km (80%), muscle fatigue (60%), fast running pace (57%), hill running (53%) and poor race preparation (42%). The most common muscle groups affected were calf (80%), hamstring (66%) and quadriceps (48%). In comparing the C and NC groups, the C group had a significantly, greater male to female ratio (32:1 vs 6:1) (p<0.05), longer history of running (6.1±5.3 vs 4.9±4.4 years) (mean±SD), shorter duration of daily stretching time (6.2±6.9 vs 7.9±5.9 min), and a greater prevalence of a positive family history of cramping (19 vs 10%) than the NC group. Weekly training load, training speed, drinking patterns during races, and Na+ intake were not different between the C and NC groups. In conclusion, EAMC is related to intense, fatigue inducing running such as racing or prolonged running (>30km), and is common in skeletal muscle groups that span across two joints. Furthermore, specific risk factors for EAMC are male gender, longer running history, shorter duration of daily stretching and a positive family history for cramping.
G-19 POSTER SKELETAL MUSCLE I