Effects of an active eccentric stretching program for the knee flexor muscles on range of motion and torque

Objective: To evaluate the changes in knee range of motion (ROM) and torque of knee flexor and extensor muscles after an active eccentric stretching program for the knee flexor muscles. Methods: Thirty-four volunteers (23 women and 11 men), aged 34.42 +/- 9.3 years, performed an active eccentric stretching program for the knee flexor muscles in the standing posture, consisting of seven repetitions of one minute each, with 30 seconds of resting between them. The stretching program was performed twice a week, for four weeks. Knee extension ROM and the torque of the knee flexor and extensor muscles were evaluated using an isokinetic dynamometer before and after the stretching program. The torque was evaluated in the isometric, isokinetic concentric and eccentric modes at 30 degrees/s and 60 degrees/s. Results: There was an increase in ROM from 53.7 +/- 13 degrees to 30.1 +/- 16 degrees (p=0.0001), in isometric torque of the flexors from 89 +/- 32Nm to 93 +/- 33Nm (p=0.01) and of the extensors from 178 +/- 67Nm to 187 +/- 73Nm (p=0.006). The concentric and eccentric torque of the flexors at 30 degrees/s increased from 90 +/- 31Nm to 96 +/- 31Nm (p=0.001) and from 100 +/- 34Nm to 105 +/- 35Nm (p=0.01), respectively. The concentric torque of the extensors at 60 degrees/s increased from 144 +/- 51Nm to 151 +/- 58Nm (p=0.02), and the eccentric torque at 30 degrees/s increased from 175 +/- 71Nm to 189 +/- 73Nm (p=0.01). Conclusions: The stretching program proposed was effective for increasing the flexibility of the stretched muscles and the torque of the agonist (stretched) muscle groups and their antagonists.