Abstract des Autors

Real-time ultrasound scanning was used to measure the angles of fibre pennation of vastus lateralis (VL) and vastus intermedius (VI) of the human quadriceps (n=12) in vivo. The maximum isometric force and cross-sectional area of the quadriceps were also measured. With the knee at right-angles the mean fibre angles for VL and VI respectively were 0.133 (0.021) rad (7.6 degrees (1.2)) and 0.143 (0.028) rad (8.2 degrees (1.6)) (mean (SD)), which is within the range of angles measured on cadavers. The mean angle decreased in going from the contracted (VL, 0.244 rad (14); VI, 0.279 rad (16)) to the stretched (VL, 0.105 rad (6); VI, 0.122 rad (7)) position. There was a significant positive correlation between fibre angle and muscle cross-sectional area but no relationship between fibre angle and force per cross-secional area. No increase in fibre angle was detected after 3 months strength training. We conclude that ultrasound can be used to measure pennation angles of superficial muscle groups but we could not demonstrate a relationship between pennation and force-generating capacity.