EFFECTS OF CONTRACT-RELAX STRETCHING TRAINING ON MUSCLE PERFORMANCE IN ATHLETES

The effects of an 8-week unilateral contract-relax (CR) stretching tra ining program (passive stretch after isometric contraction) on muscula r performance were investigated in a group of 16 athletes, The flexibi lity, maximum torque and angular position as well as contraction work in movements of the knee joint were determined before training and aft er 4 and 8 weeks of training. The torque measurements were performed u nder isokinetic conditions, eccentrically at angular velocities of 60 degrees.s(-1) and 120 degrees.s(-1) isometrically at five different jo int positions, and concentrically at angular velocities of 60, 120, 18 0 and 240 degrees.s(-1) using and iso-kinetic dynamometer. A surface e lectromyogram (EMG) of the thigh muscles (quadriceps and hamstrings) w as recorded simultaneously. As compared to untrained control limbs, si gnificant improvements in active and passive flexibility (up to 6.3 de grees in range of motion), maximum torque (up to 21.6%) and work (up t o 12.9%) were observed, and these were especially pronounced under ecc entric load conditions. A comparison between integrated EMG recordings during eccentric and concentric loads, as well as the interpretation of the training-induced changes in the EMG, suggest that muscular acti vity under eccentric loads may be impaired by mental processes.