[Isokinetic measurements of the stretch strength of the femoral quadriceps muscle in surfers in comparison to healthy, untrained persons].

The strength of the quadriceps muscle of twelve male surfers who practice their sport for more than 10 years was compared with results of 15 male untrained persons. The concentric peak torque of knee extensors was measured every 10 degrees in a range from 90 to 20 degrees isometrically and dynamically with a constant angle velocity of 10 degrees/sec. The difference in torque between the left and the right leg is not significant, but there is a slight dominance in favour of the standing leg. The body weight related strength of the surfers was 3.2 Nm/kg indicating a higher strength characteristic compared to 2.7 Nm/kg of untrained subjects. Moreover the strength values of our group of athletes were above the value of 3 Nm/kg, which is referred to in the literature as representing a good training status. In view of these results it can be concluded that a long-lasting specific training like surfing will change the strength characteristics of the quadriceps muscles, although none of the surfers had undertaken an extensive strength training for the lower extremity.