Reduction in range of movement can increase maximum voluntary eccentric forces for the human knee extensor muscles

Using the KinCom 500H isokinetic dynamometer the first part of this study m easured the characteristics of the force velocity relationship curve for th e human knee extensors between -1.57 (eccentric) and 3.67(concentric) rads . s(-1) (-90 and 210 degrees s(1)) for both legs in 4 subjects. A significa nt increase in force generation was seen in eccentric activity at 0.52 rads . s(-1) (30 degrees s(-1)) but not at 1.57 rads . s(-1) (90 degrees s(-1)) compared to maximum voluntary isometric force (P < 0.005). This increase w as, however, lower than would be expected from the classical force-velocity relationship. The second part of the study examined whether restricting th e range of movement was able to further increase the eccentric forces. In a further 6 subjects, the eccentric contractions were repeated during either an 80 degrees (15-95 degrees flexion) and a 50 degrees (45-95 degrees flex ion) range of movement. Significant increases in force were seen over the s horter range of movement at 0.52 rads . s(-1) (30 degrees s(-1)) (P = 0.006 ) and 1.57 rads . s(-1) (90 degrees s(-1)) (P < 0.001).