SynthesisSports medicine (Auckland, N.Z.)2026
Repetitive Head Impacts During Contact Sports and Fluid Biomarkers of Neural Damage: A Meta-analysis.
Synthesis in Sports medicine (Auckland, N.Z.), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors.
Funding
Abstract
backgroundGrowing evidence indicates that former professional contact sports athletes are at increased risk of neurodegenerative disease, potentially linked to repetitive head impacts (RHI). Research into the acute effects of RHI on fluid biomarkers of neural damage can contribute to the identification of underlying pathophysiological processes.
objectivesTo systematically aggregate the acute effect of contact sport participation on fluid biomarkers of neural damage.
methodsMEDLINE, Embase and SPORTDiscus were searched up to 18 July 2024. Studies that were included assessed fluid biomarkers of neural damage before and within 24 h after a single session of contact sport participation. Studies on mild traumatic brain injury were excluded. Risk of bias was assessed using the Bias in Non-randomized Studies of Exposure tool and the Risk of Bias Tool 2. The level of evidence was synthesized according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. Meta-analysis was performed for natural and experimental exposure to RHI separately, while also differentiating for contact sports and biomarkers in subsequent analyses.
resultsThirthy-three studies (representing 892 participants) were included for meta-analysis. Meta-analysis on natural exposure revealed medium-to-large-sized elevations across blood biomarkers for fight sports (k = 7), American Football (k = 9) and football (soccer) (k = 2). Very few studies (8%) controlled for the confounding effects of physical exercise or blood volume change, introducing considerable risk of bias. Meta-analysis on experimental exposure to football heading revealed no significant change in blood biomarkers of neural damage (k = 11, n = 236, d = 0.108, 95% CI = -0.047 to 0.263, p = 0.172), and the experimental heading groups also showed no difference in pre-post change compared with control groups (k = 8, heading = 174, controls = 151, d = -0.115, 95% CI = -0.452 to 0.223, p = 0.505).
conclusionThe current literature provides convincing evidence for acute elevations of blood biomarkers after a single session of contact sports participation. However, due to considerable risk of bias in existing literature, this evidence is very uncertain regarding the acute effect of contact sports participation on brain integrity (GRADE level of evidence: very low). On the basis of meta-analysis of the available literature (including S100B, neurofilament light chain and total-tau), the evidence is very uncertain about the acute effects of football heading on brain integrity within 24 h after exposure (GRADE level of evidence: very low). In the light of the increased risk of neurodegenerative disease in former professional contact sport athletes, there is a need for well-powered and controlled prospective studies on the acute and long-term effects of contact sport participation on brain integrity. TRIAL REGISTRY: PROSPERO number: CRD42023461119.
Identifiers
42839221What Socratic holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.