The Effect of a Novel 8-Week Strengthening Program on Isometric, Multidirectional Cervical Strength in Adolescent...

Pryce, R, O'Brien, R, Dillon, J, and Fleming, N. The effect of a novel 8-week strengthening program on isometric, multidirectional cervical strength in adolescent male rugby players. J Strength Cond Res XX(X): 000-000, 2026-Rotational head acceleration is a primary mechanism in sports-related concussion, yet standard neck conditioning often neglects the transverse plane. The purpose of this study was to compare a rotation-specific neck-strengthening protocol vs. a conventional program on multidirectional isometric strength in 32 adolescent male rugby players. Participants were stratified by baseline strength into 3 groups: Control, Conventional (flexion/extension/side-flexion), and Rotation (Conventional plus rotation). Supervised interventions ran twice weekly for 8 weeks, incorporating isotonic exercises and sphygmomanometer-monitored isometrics for individualized loading. Strength, circumference, and range of motion were assessed pre- and post-intervention by blinded assessors. A significance level of p < 0.008 was chosen for all outcome measures to control for family-wise error across the tests. Both the Conventional (p < 0.0001, d = 0.89) and Rotation (p < 0.0001, d = 0.84) programs resulted in significant improvements in total multidirectional neck strength with large effects, whereas the Control did not. Significant time effects were observed for flexion, extension, and rotation (p ≤ 0.0002; η2p = 0.39-0.62). For rotation specifically, a significant group × time interaction occurred (p = 0.003). Post hoc analysis confirmed that only the Rotation group significantly exceeded Control values (p = 0.028, d = 1.31), with many changes exceeding minimal detectable change at the 95% confidence level thresholds. Neck circumference increased significantly in both Rotation (p < 0.0001, d = 0.77) and Conventional (p = 0.008, d = 0.37) groups. Conventional neck training is effective for general conditioning but does not maximize rotational adaptations compared with plane-specific training. Developing cervical rotation strength may represent a modifiable biomechanical factor associated with concussion risk in youth sport.