Endurance time, pain and resumption in passive loading of the elbow joint

This study investigated reactions in passively loaded, fully extended elbow joints in 13 men. Pain reactions during and after loading were studied, as were endurance time, T(end), and resumption time, Tr. The loading moment on the elbow joint, Mn, varied between 7 and 100% of maximum elbow moment. Discomfort/ pain was estimated with Borg's CR-10 scale. T(end) decreased with increasing load level. The opposite was found for the resumption time: the higher the load, held until T(end), the shorter the Tr. The pain limiting the working capability originated mainly from muscle tissue and not from the joint itself. It is concluded that the relation between load and endurance time for passively loaded, fully extended elbow joints resembles that for muscular loading in more 'normal' postures. Equations for estimation of endurance and resumption times (in minutes) for fully extended joints are proposed: T(end) = 20.6e(-6.04Mn) and Tr = 0.0167e(8.84/(1.46+0.346Mn)), respectively.