Fig. 8. Hypothesized relationship of performance constraints between a sagittal plane extensor muscle and a frontal plane stabilizer muscle (e.g. foot invertor). As track radius decreases, the ratio of extensor muscle force generation to joint stabilizer muscle force (indicated by slope of solid lines) decreases as frontal plane stabilization becomes increasingly important at these tighter curves. Along the straight path, joint stabilizers play a negligible role in limiting speed and maximum sprint speed is constrained only by a maximum extensor muscle force limit (F_(ext)max, broken horizontal line). On a curved path, however, the importance of joint stabilization in the frontal plane becomes increasingly important with smaller radii, and sprint speed may become increasingly limited by the ability of a group of joint stabilizer muscles to generate force (e.g. F_(inv)max, broken vertical line). Open circles denote the hypothetical maximum attainable sprint speed for a given track radius.