Fig. 6. Normalized peak resultant ground reaction forces (body weights, BW) for the outside leg (triangles) and inside leg (inverted triangles) as a function of radius (R) during normal curve sprinting (A) and curve sprinting with a tether (B). Contrary to current curve sprinting theory (Greene, 1985), axial leg force (represented here by resultant GRF) decreased with decreasing radius. During normal curve sprinting, the outside leg generates significantly greater axial leg force than the inside leg force (A). With the addition of an external centripetal force provided by a tether rope, however, each leg produces the same axial leg force (B). Values are means ± s.e.m. for all subjects at each radius. The broken line indicates average peak force on straight path; the gray band indicates ± s.e.m. Lines represent power fits of the outside leg (solid line) and inside leg (broken line) data. For normal curve sprinting: resultant GRF of outside leg=2.27R^0.091 (r²=0.983); resultant GRF of inside leg=1.87R^0.156 (r²=0.985). For tethered curve sprinting: resultant GRF of outside leg=2.16R^0.155 (r²=0.976); resultant GRF of inside leg=2.09R^0.176 (r²=0.977).