Neck strength and force in reaction time task of adolescent athletes with and without concussion history: A pilot study

Objectives: Assess the impact of concussion by comparing reaction time, peak force recruitment, and rate of force development of adolescent athletes returning from concussion against age- and sex-matched controls in visual-elicited neck movement. Design: Athletes sat secured in a custom-built isometric device with their heads secured in a helmet and attached to a 6-axis load cell. They performed neck flexion, extension, and lateral flexion in response to a visual cue. Three trials in each direction were used for statistical analyses; peak force and rate of force development were normalized against athlete mass. Setting: Laboratory. Participants: 26 adolescent/young adult athletes (8F/18M), either recently concussed (and cleared for return to sport) or an age- and sex-matched healthy control. Main outcome measures: Reaction time, angle, standard deviation of angle, deviation from target angle, peak force, and RFD over 50, 100, 150,and 200 ms of movement were measured for each trial. Results: Concussed athletes had decreased normalized peak force (P = 0.008) and rate of force development (P < 0.001–0.007). In neck extension, concussed athletes also had decreased movement precision (P = 0.012). Conclusions: Concussion is associated with alterations of neck biomechanics that decrease overall neck strength.