Isokinetic neck strength norms for schoolboy rugby forwards

Abstract

Objective. To generate isokinetic neck strength norms for schoolboy rugby forwards.
Design. Two hundred and eight schoolboys (17.21 – 1.03 years, mean – standard error of the mean (SEM), chosen from a population of under-19 first and second XV rugby players, participated in this study. The subjects were assessed anthropometrically and isokinetically according to a set protocol. The isokinetic assessment of neck strength was performed with the use of a specially designed stabilising chair and halo. The subjects performed a single maximal exertion set, consisting of 3 repetitions, through each of the cervical spinal movements in the sagittal and frontal planes. The data were analysed statistically according to positional categories (front-, second-, and back-row forwards), and were used to generate Stanine tables of normative data concerning the force characteristics of the cervical spine.
Results. The front-row forwards produced the largest amounts of force during the measurement of peak torque flexion (PTF = 30.00 – 1.39 Nm) and peak torque extension (PTE = 55.26 – 1.42 Nm). Conversely, the second-row forwards performed the best during the measurement of lateral flexion peak torque to the right (PTR = 53.71 – 1.51 Nm) and lateral flexion peak torque to the left (PTL = 52.92 – 1.63 Nm) in the frontal plane. The front-row forwards were the most powerful in all the neck movements measured (power generated at 0.2 seconds during flexion (PowF) = 101.54 – 6.43 W, power generated at 0.2 s during extension (PowE) = 167.31 – 8.03 W, power generated at 0.2 s during lateral flexion to the right (PowR) = 211.92 – 7.44 W, and power generated at 0.2 s during lateral flexion to the left (PowL) = 194.81 – 7.73 W). However, further analysis of the data revealed that few statistically significant differences (p < 0.01 and p < 0.05) existed between the positional categories for the measured variables of peak torque, power generated at 0.2 of a second, peak torque to body mass ratio and cervical range of motion.
Conclusion. It appears that the various positional categories have not undergone the expected neck strength adaptations to meet the unique requirements of each position. The generation of neck strength normative data allows for the effective and quantified comparison of neck strength variables, enabling more effective injury prevention and rehabilitation.
South African Sports Medicine Vol.17(1) 2005: 19-26