Background.　Many　sports　and　physical　activities　can　result　in　lower　limb　injures.　Pedaling　is　an　effective　exercise　for　lower　extremity　rehabilitation,　but　incorrect　technique　may　cause　further　damage.　To　some　extent,　previous　experiments　have　been　susceptible　to　bias　in　the　sample　recruited　for　the　study.　Alternatively,　methods　used　to　simulation　activities　can　enable　parametric　studies　without　the　influence　of　noise.　In　addition,　models　can　facilitate　the　study　of　all　muscles　in　the　absence　of　the　effects　of　fatigue.　This　study　investigated　the　effects　of　crank　length　on　muscle　behavior　during　pedaling.　Methods.　Six　muscles　(soleus,　tibialis　anterior,　vastus　medialis,　vastus　lateralis,　gastrocnemius,　and　rectus　femoris),　divided　into　three　groups　(ankle　muscle　group,　knee　muscle　group,　and　biarticular　muscle　group),　were　examined　under　three　cycling　crank　lengths　(100　mm,　125　mm,　and　150　mm)　in　the　present　study.　In　addition,　the　relationship　between　crank　length　and　muscle　biological　force　was　analyzed　with　the　AnyBody　Modeling　System　(TM),　a　human　simulation　modeling　software　based　on　the　Hill-type　model.　Findings.　Based　on　inverse　kinematic　analysis,　the　results　indicate　that　muscle　activity　and　muscle　force　decrease　in　varying　degrees　with　increases　in　crank　length.　The　maximum　and　minimum　muscular　forces　were　attained　in　the　tibialis　anterior　and　vastus　lateralis,　respectively.　Interpretation.　Studying　the　relationship　between　muscle　and　joint　behavior　with　crank　length　can　help　rehabilitation　and　treating　joint　disorders.　This　study　provides　the　pedal　length　distribution　areas　for　patients　in　the　early　stages　of　rehabilitation.