Total muscle fiber and tendon work across increasing walking speeds (net musculotendon work (MTnet), positive tendon work (TenPos, elastic energy recovered from the tendon), negative fiber work (FibNeg) and positive fiber work (FibPos)). The percent difference in muscle work between stance and swing decreases as walking speed increases. Note, the percent of elastic energy recovery in the tendons (Ten Pos/ (FibPos +TenPos)) was maximized at 30% when walking at 1.2 m/s, which is near the preferred walking speed. [Adapted from Neptune RR, Sasaki K, Kautz SA. The effect of walking speed on muscle function and mechanical energetics. Gait Posture. 2008; 28(1): 135–43. Copyright © 2008 Elsevier. Used with permission.]