%X 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 h, 24 h and 7 days after heading. Serum NF-L was quantified using Quanterix NF-L assay kit on the Simoa HD-1 Platform. RESULTS: erum 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^{− 1} (5.00–7.00 pg · ml^{− 1}); 6 h post 6.50 pg · ml^{− 1} (5.70–7.29 pg · ml^{− 1}); 24 h post 6.07 pg · ml^{− 1} (5.14–7.01 pg · ml^{− 1}); and 7 days post 6.46 pg · ml^{− 1} (5.45–7.46 pg · ml^{− 1})]. 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. %J Science and Medicine in Football %A K Austin %A BJ Lee %A TR Flood %A J Toombs %A M Borisova %A M Lauder %A A Heslegrave %A H Zetterberg %A NA Smith %O This version is the author accepted manuscript. For information on re-use, please refer to the publisher's terms and conditions. %I TAYLOR & FRANCIS LTD %L discovery10118876 %V 5 %D 2021 %N 3 %K Soccer, heading, brain injury, axonal damage, biomechanics %T Serum neurofilament light concentration does not increase following exposure to low velocity football heading %P 188-194