RELATIONSHIP BETWEEN ISOKINETIC STRENGTH AND FIELD TESTS OF PHYSICAL FITNESS IN ELITE JUNIOR TENNIS PLAYERS 758

Abstract

The objective of this study was to examine the relationship between isokinetic trunk strength and several field tests of physical fitness in elite junior tennis players. Measurements were obtained on 60 nationally ranked junior tennis players between 13 and 17 years of age. Trunk flexion and extention data were obtained concentrically on a Cybex 6000 Isokinetic dynamometer with TEF modular component at speeds of 60°/sec (5 reps) and 120°/sec (15 reps). Peak torque/body weight and work/body weight ratios were statistically analyzed in comparison to the field tests. The field tests consisted of a standardized fitness testing protocol which included measurements of strength, power, speed and agility, endurance and flexibility. The results indicated significant correlations (p<0.05) between the isokinetic measurements and a series of muscular speed and power measurements(grip strength, vertical jump, spider agility run and lateral shuffle), while correlations between isokinetic measurements and muscular endurance activities(number of sit-ups and push-ups in one minute, 1½ mile run) were non-significant. These results demonstrate that the isokinetic testing protocol at both speeds is a better indicator of speed and power in these tennis players than the muscular endurance tests utilized in this study. In addition, even though the sit-up test utilizes the same muscle groups as the isokinetic tests, the lack of a significant correlation supports the concept of speed and muscular length specificity in both testing and designing programs for elite junior tennis players.