Maximal voluntary quadriceps strength patterns in Olympic overtrained athletes

Peak torques were studied in 10 elite male overtrained athletes and 10 controls matched for sex, age, sport, and performance level. Isokinetic concentric (CON) and eccentric (ECC) maximal voluntary contractions (MVC) of quadriceps muscle were assessed at the angular velocities of 60 degrees, 120 degrees, and 180 degrees.s-1. Sustained isometric MVCs were also measured at knee angles of 10 degrees, 45 degrees, and 80 degrees of flexion. Six seconds after the beginning of each isometric MVC, a 40-Hz electrical stimulation was superimposed on the MVC for a further 6 s. The overtrained subjects developed significantly smaller CON peak torques at 180 degrees.s-1 (P < 0.001), although ECC torques were similar at all three velocities. ECC/CON ratios were higher in the overtrained subjects at 120 degrees.s-1 (P < 0.01) and 180 degrees.s-1 (P < 0.001) compared with the controls. Isometric MVCs at 10 degrees and 45 degrees knee flexion were lower in the overtrained at P < 0.01 and P < 0.05, respectively. Also in the overtrained subjects, at knee angle of 10 degrees, the addition of the electrical stimulation to the isometric MVC produced an increase (P < 0.05) in torque levels. It is suggested that impaired central drive may account for the present findings.