Objectives
To investigate if heading frequency and impact biomechanics in a single session influence the concentration of serum neurofilament light (NF-L), a sensitive biomarker for axonal damage, up to 7 days after heading incident at ball velocities reflecting basic training drills.

Methods
Forty-four males were randomized into either control (n=8), 10 header (n=12), 20 header (n=12) or 40 header (n=12) groups. Linear and angular head accelerations were quantified during heading. Venous blood samples were taken at baseline, 6 hours, 24 hours and 7 days after heading. Serum NF-L was quantified using Quanterix NF-L assay kit on the Simoa HD-1 Platform.

Results
Serum NF-L did not alter over time (p=0.44) and was not influenced by number of headers [p=0.47; mean(95% CI) concentrations at baseline 6.00 pg/ml (5.00 – 7.00 pg/ml); 6 hours post 6.50 pg/ml (5.70 – 7.29 pg/ml); 24 hours post 6.07 pg/ml (5.14 – 7.01 pg/ml); and 7 days post 6.46 pg/ml (5.45 – 7.46 pg/ml)]. There was no relationship between percentage change in NF-L and summed session linear and angular head accelerations.

Conclusion
In adult men, heading frequency or impact biomechanics did not affect NF-L response during a single session of headers at ball velocities reflective of basic training tasks.