Head injuries are prevalent in collegiate athletics with concussions being common among contact sports, such as football. Concussion assessment and diagnosis is complicated by the lack of objective and aassessment techniques. The purpose of the study was to determine if there is a relationship between the level of a concussion-related biomarker, self-report (subjective) head hits, video-analyzed head hits, and ImPACT test scores in college football athletes before and after a football practice session.

After being recruited and consented to participate, 29 Division I college football athletes provided a blood sample via finger stick two days before a 2014 spring football season practice and within within 4 hours post-practice.

The blood samples were processed to generate serum samples, and these serum samples were tested using a S100B ELISA kit to measure the amount of S100B. A computerized concussion diagnosis test (ImPACT) was completed by each subject before and after the practice. Video recordings of the practice were used to objectively count the number of hits that each participant sustained during the practice.

The major results are as follows. None of the participants suffered a concussion based on current diagnostic concussion assessments, including a symptom checklist, Standardized Assessment of Concussion (SAC), and Balance Error Scoring System (BESS). The participant who suffered head hits (as determined by video review) during practice had a serum S100B level that increased from 39.5 pg/ml pre-practice to 85.3 pg/ml post-practice. In comparison, three other participants who did not sustain head hits (as determined by video review) had decreased or a minimal increase in the serum S100B level.

Due to the limited number of samples (15 out of 76) that had a CV < 15%, the relationships between biomarker difference scores and head hits and ImPACT scores were not conducted. However, the relationship between video-analyzed head hits and the five ImPACT test composite scores was a negative correlation:​ r = –0.10, p = 0.29;​ r = – 0.11, p < 0.01;​ r = –0.17, p = 0.02;​ r = –0.01, p = <0.01;​ r = –0.15, p = 0.10). The subjective Head Hit Index (HHI) was negatively correlated with 3 of the 5 composite scores (r = –0.38, p = 0.04;​ r = –0.12, p < 0.01;​ r = 0.08, p < 0.01;​ r = 0.05, p = <0.01;​ r = –0.22, p < 0.01). The verbal memory score of the ImPACT test had the highest correlation (r = –0.38, p = 0.04) with the subjective HHI.

In conclusion, an increased serum S100B level may be linked to sub-concussive head hits during collegiate football practice. Because an increase in serum S100B level likely represents trauma to the brain, sub-concussive hits may cause mild brain injury.

The major clinical implication of this study’s findings relates to the objective clinical data that an athletic trainer needs for diagnosing brain trauma. For an athletic trainer to provide comprehensive care to football players, the athletic trainer needs objective clinical data, such as biomarker data. However, the collection of blood samples on the sidelines is a challenge. Based on this study’s findings, the collection of blood via finger stick is feasible. Therefore, in the future, the athletic trainer might be able to obtain biomarker data to aid in the diagnosis of brain trauma.