A calf stretch is a rehabilitation exercise to improve knee extension.

Demonstrating a calf stretch.
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CLINICAL PUBLICATIONS
Acute Effects of Static Stretching of Hamstring on Performance and Anterior Cruciate Ligament Injury Risk During Stop-Jump and Cutting Tasks in Female Athletes. Ruan M, Zhang Q and Xie Wu, X. J Strength Cond Res. 2017 May; 31(5): 1241–1250.
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