Posteromedial middle one-third tibial pain and tender ness associated with stressful activities has been pre viously recognized as occurring at the origin of the flexor digitorum longus muscle. Seventeen running ath letes with this clinical syndrome were evaluated with regard to second toe range of motion and foot intrinsic muscle strength. The results were compared to results obtained from a comparable group of asymptomatic athletes. Statistical analysis of the results of the evaluation indicated a significant displacement of the arc of motion of the second toe in the symptomatic athletes toward extension of the metatarsophalangeal joint and a de crease in flexion. Weakness or dysfunction of the intrin sic muscles in the symptomatic athletes was also found to be significant. This analysis supports the hypothesis that posteromedial middle one-third tibial stress symp toms may be related to overuse of the flexor digitorum longus muscle associated with mild claw toe deformity. © 1989, SAGE Publications. All rights reserved.