Proximal redistribution of joint work to the hip occurs following intensive running in novice runners [1] and might explain the reduced running economy following prolonged running [2]. These findings in novice might be different in well-trained runners due to their training status. PURPOSE: The purpose of this study was to assess if proximal redistribution of joint kinetics following a running bout is observed in well-trained runners. METHODS: 14 well-trained male runners with habitual rearfoot strike patterns (76±22km/week) completed 5 running trials at a speed equivalent to ±5% of their long run pace while 3D kinematic and ground reaction force data were collected before and after a treadmill run equal to 25% of weekly mileage (19±6km). Joint powers and work were calculated from these data using Visual3D. Percent contribution of each joint work relative to total lower limb joint work was computed. Paired samples t-tests were used to compare joint kinetics before and after the run (p < 0.05). Cohen’s d effect sizes were computed to assess mean difference magnitudes. RESULTS: Peak ankle negative power (Table 1) and hip negative relative work contribution (pre: 14.3±3.6%, post: 15.6±4.5%, p=0.041; d=0.33) showed significant pre- to post-run effects. Positive ankle (pre: 50.6±6.8%, post: 49.5±7.3%, p=0.35; d=0.16) and hip relative work (pre: 26.2±10.1%, post: 27.1±8.8%, p=0.53; d=0.10) were unaffected by the long run in these well-trained male runners. CONCLUSIONS: These findings suggest that previously reported distal-to-proximal shift in positive joint work in novice runners following a running bout [1] is not observed in well-trained male runners. This might be the result of chronic training exposure in these trained runners and suggest a preservation of mechanical joint output despite prolonged running exposure. Differences in run type (intense vs steady prolonged run), foot strike, and gender might also be responsible for these differences between studies.Table 1: Peak negative and positive joint powers (W·kg-1) before and after the prolonged run (mean±SD).