Change of Muscle Activity as Well as Kinematic and Kinetic Parameters during Headers after Core Muscle Fatigue

Study Overview: Core Muscle Fatigue and Soccer Headers. In soccer, heading the ball is a unique tactical skill, but it comes with potential long-term health risks related to acceleration forces on the head and concussions. Proper motion technique requires the acceleration generated by the core muscles, while the cervical spine and head are stabilized by the co-contraction of neck flexors and extensors. This study sought to identify whether changes in kinematics and muscular activity—especially of the head-stabilizing muscles—occur during headers when the core musculature is fatigued. Methodology & Setup. A total of 41 amateur soccer players were examined during straight headers on a motionless pendulum header. Testing occurred before and after their core muscles were fatigued through a specific exercise program. Muscular Activity Analysis: 12 players were evaluated using telemetric surface electromyography (Noraxon TeleMyo TG2) to measure myoelectric potential., Kinematic and Kinetic Analysis: 29 players were assessed using a 3D acceleration sensor, a force plate, and video recordings to capture movement techniques and ground reaction forces. Key Findings in Neuromechanics and Kinematics. The data revealed significant biomechanical alterations resulting from core fatigue:. Core Muscle Activity: The activity of the M. erector spinae and M. rectus abdominis was significantly reduced during the preparation phase of the header., Neck Muscle Compensation: The activity of the M. sternocleidomastoideus significantly increased during the jump phase, suggesting an altered stabilization strategy., Kinematic Reductions: The hip extension angle during maximum arched body tension was significantly reduced under fatigue. Consequently, jumping height, acceleration force impulse, and linear head acceleration were also significantly reduced. Clinical and Training Implications. The study concludes that fatigue of the core muscles significantly affects both the motion technique of the header and the activity of the muscle groups responsible for stabilizing the head. From a medical-preventive perspective, these findings highlight the necessity of specific, targeted training for both core and neck muscles in soccer players to maintain protective stabilization during late-game scenarios.