  A Hill-type model is proposed for the extension-flexion cycle of human knees
during bicycle riding. The extension-flexion cycle is controlled by a synergy
of muscular excitations and contractions of the knee musculature. Muscular
action potentials are modeled by Sine-Gordon kinks, while titin-influenced
actomyosin contractionsare modeled by Korteweg-de Vries solitons. As an
application, the total knee arthroplasty is discussed.
