Abstract
Elite level tennis players have shown a high incidence of lower back injuries. The objective of this study was to generate a descriptive profile of trunk extension and flexion strength as well as to examine the relationship between 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 extension data were obtained concentrically on a Cybex 6000 Isokinetic dynamometer with TEF modular component at speeds of 60° s−1 and 120° s−1. Peak torque/body weight and work/bodyweight ratios were statistically analyzed in comparison to the field tests. A descriptive profile of isokinetic flexion/extension ratios was generated for elite junior tennis players. Trunk flexion/extension ratios ranged from 102 to 122% for peak torque at 60° s−1 and 120° s−1. The field tests consisted of a standardized fitness testing protocol which included measurements of strength, power, speed and agility, endurance and flexibility. The correlated measurements included the total distance thrown on a forehand, backhand, overhead, and reverse overhead medicine ball toss. The analyses yielded significant correlations (range 0.47–0.82) between all isokinetic trunk flexion/extension data and the series of four medicine ball tosses, which were used in the field as a measurement of power (P < 0.01). These results demonstrate the relationship between isokinetic trunk testing and functional movement patterns. In addition, the isokinetic testing results provide an initial profile of trunk flexion and extension strength in elite junior tennis players.