Objective The purpose of this paper was to investigate the effects of acyclic exercise and manipulation on the biomechanical properties of patellar ligament of rabbits. Methods The rabbits underwent acyclic exercise for 3 weeks by an electric cage method and received the manipulations to the rear limbs at the same periods.Results Acyclic exercise increases the velocity of stress relaxation, reduces the elastic modulus of rabbit patellar ligament. In addition, the strain in stress-strain curve shifted to right. The manipulation had a beneficial effect for recovery of these biomechanical behaviors. Conclusion The acyclic exercise induces the relaxation of ligament and the manipulation can prevent it.