Pre-Season Baseline Testing for Concussion: What Every Clinician Needs to Know
Individual variation in symptoms, cognition, balance, and vestibular-ocular function means normative data alone is not enough. Pre-season baselines transform post-injury assessment from guesswork into precision medicine.
Why Baseline Testing Matters
Concussion assessment is fundamentally a comparison exercise. When an athlete sustains a head injury, the clinician's task is to determine whether their current neurocognitive, vestibular, and postural function has declined from their normal state. Without knowing what “normal” looks like for that individual, this determination relies on population-based normative data -- and that is where the problem begins.
Individual variation across the domains assessed by the SCAT6 is substantial. McCrea et al. (2003) demonstrated that healthy, uninjured athletes show a wide range of performance on the Standardized Assessment of Concussion (SAC), with baseline scores ranging from 23 to 30 out of 30. An athlete who scores 26 post-injury might be performing normally -- or might have dropped 4 points from their personal baseline. Without that baseline, the clinician cannot tell.
The same principle applies to symptom endorsement. Healthy athletes frequently endorse symptoms at baseline. Covassin et al. (2009) found that up to 75% of uninjured collegiate athletes endorse at least one symptom on the SCAT symptom checklistat pre-season testing. Common baseline symptoms include fatigue, difficulty concentrating, and sleep disturbance. If a clinician interprets any symptom endorsement as evidence of concussion without knowing the athlete's baseline symptom profile, false positive rates increase dramatically.
Pre-season baseline testing solves this problem. By establishing individualised reference values before the season begins, clinicians gain the ability to detect genuine change from normal function after injury -- dramatically improving both the sensitivity and specificity of post-injury concussion assessment (Broglio et al., 2007).
What to Test at Baseline
A comprehensive pre-season baseline should capture function across all four domains assessed in post-injury concussion evaluation. Each component provides a distinct piece of the clinical puzzle, and collectively they form a personalised reference profile that transforms post-injury interpretation.
1. SCAT6 Symptom Checklist
Record the athlete's baseline symptom endorsement using the full 22-item SCAT6 symptom checklist. Document both the number of symptoms endorsed (0-22) and the total severity score (0-132). This establishes their “normal” symptom profile. Many healthy athletes endorse 1-3 symptoms at baseline, particularly fatigue, difficulty concentrating, and trouble falling asleep (Covassin et al., 2009). Knowing this prevents false positive identification of concussion based on pre-existing symptom endorsement.
2. SAC Cognitive Assessment
Administer the full Standardized Assessment of Concussion (SAC) embedded within the SCAT6: orientation (5 points), immediate memory -- 5- and 10-word lists (15 or 30 points), concentration including digits backward (5 points), and delayed recall (5 or 10 points). Baseline SAC scores vary considerably between individuals. McCrea et al. (2003) reported a mean baseline SAC score of approximately 26.3 with a standard deviation of 2.1. A post-injury score of 24 might be unremarkable for one athlete but represent a clinically significant decline for another.
3. mBESS Balance Assessment
Complete the modified Balance Error Scoring System (mBESS): three stances (double leg, single leg, tandem) on a firm surface, each held for 20 seconds. Record total errors for each stance and the composite score. Individual variation in baseline mBESS is significant -- baseline error counts range from 0 to 15+ depending on the athlete's age, sport, and innate postural stability. Also record tandem gait time (best of four trials over 3 metres). These individual baselines are essential for determining whether a post-injury balance score represents genuine impairment (Broglio et al., 2007).
4. VOMS Vestibular-Ocular Motor Screening
Administer the full VOMS battery: smooth pursuits, saccades, near point of convergence (NPC), vestibulo-ocular reflex (VOR horizontal and vertical), and visual motion sensitivity (VMS). Record symptom provocation scores (headache, dizziness, nausea, fogginess on a 0-10 scale) for each domain and NPC distance in centimetres. Baseline VOMS establishes each athlete's normal vestibular-ocular response profile. Post-injury, a symptom provocation increase of 2 or more points above baseline on any subtest, or an NPC of 5 cm or greater (if baseline was normal), is clinically significant (Mucha et al., 2014).
5. King-Devick Test (Optional but Valuable)
The King-Devick test measures saccadic eye movements and attention by timing the athlete as they read aloud a series of single-digit numbers displayed on cards. Baseline establishes the individual's normal reading speed. Post-injury slowing of 3-5 seconds or more from baseline is associated with concussion. While not part of the SCAT6, the King-Devick is a rapid (2-minute), validated sideline screening tool that complements the standard assessment battery (Galetta et al., 2011).
When to Conduct Baseline Testing
The timing and conditions of baseline testing directly affect data validity. A baseline conducted under suboptimal conditions is worse than no baseline at all, because it creates a false reference point that can lead to incorrect post-injury interpretation.
Timing Guidelines
- Pre-season: Conduct baselines during the pre-season period, ideally 2-4 weeks before competition begins. This allows time for retesting if data validity is questionable.
- Annual renewal: Baselines should be repeated annually. Neurocognitive function, postural stability, and vestibular-ocular profiles change over time -- particularly in developing adolescent athletes. A two-year-old baseline may no longer be representative (Echemendia et al., 2023).
- Post-concussion re-baseline: After an athlete has fully recovered from a concussion and been cleared to return to sport, consider establishing a new baseline. Their “normal” may have shifted, and the pre-injury baseline may no longer be valid.
Conditions That Invalidate Baseline Data
Testing under any of the following conditions produces unreliable baselines that should not be used for post-injury comparison:
- Within 24 hours of vigorous physical exertion or competition
- Following a night of fewer than 7 hours of sleep
- Under the influence of alcohol, cannabis, or other substances (including residual effects)
- While acutely unwell (e.g. upper respiratory tract infection, migraine episode)
- While recovering from a previous concussion that has not been fully cleared
Document the conditions of testing: date, time, hours of sleep the previous night, time since last physical activity, and any current symptoms or illnesses. This contextual data is essential for interpreting the baseline and determining its validity if it is later used for post-injury comparison.
How to Implement in Practice
The practical implementation of baseline testing differs significantly between team-based settings and individual athlete consultations. Both require systematic planning, but the logistics vary.
Team-Based Workflow
- Schedule dedicated baseline sessions 2-4 weeks pre-season
- Allow 15-20 minutes per athlete for the full battery
- Test in a quiet, distraction-free environment -- not on the field during training
- Stagger athletes to avoid group testing effects on cognitive measures
- Instruct athletes on the importance of genuine effort before testing
- A team of 30 athletes can be baselined across 2-3 sessions
Individual Athlete Workflow
- Integrate into the pre-participation medical examination
- Allocate an additional 15-20 minutes to the standard consultation
- Screen for invalidating conditions before commencing
- Store baseline data where it can be accessed rapidly if a concussion occurs
- Provide the athlete with a summary of their baseline results
- Flag in clinical records that a baseline exists and its date
Regardless of setting, the critical requirement is that baseline data must be securely stored and readily accessible at the point of care when a concussion occurs. A baseline sitting in a filing cabinet at the clinic while the athlete is being assessed on the sideline is of limited value. Digital platforms that store baseline and post-injury data in a single accessible system provide a significant workflow advantage.
Common Pitfalls & Validity Threats
Baseline testing is only useful if the data is valid. Several well-documented threats to validity must be actively managed by the clinician.
Sandbagging (Deliberate Underperformance)
This is the most frequently cited concern with baseline testing. Athletes may deliberately perform poorly at baseline in the belief that a low baseline score will make it easier to “pass” post-injury testing and return to play faster. Research by Erdal (2012) confirmed that motivated athletes can intentionally suppress their scores on neurocognitive tests, particularly on memory and processing speed tasks.
Mitigation strategies: Educate athletes about why honest baseline performance protects them (a falsely low baseline means genuine impairment may be missed after injury, putting them at risk). Use embedded validity indicators -- the SCAT6 SAC includes performance patterns that can flag implausible scores (e.g. perfect orientation but very low immediate recall). Compare baseline scores to normative ranges; scores that fall well below expected norms without explanation should trigger retesting.
Suboptimal Testing Conditions
Testing in noisy environments, immediately after physical exertion, in group settings where athletes can overhear each other's responses, or when athletes are fatigued or distracted produces unreliable data. The testing environment must be controlled: quiet, one-on-one administration, with the athlete rested and attentive.
Practice Effects & Word List Management
The SAC uses standardised word lists for immediate and delayed recall. If the same word list is used at baseline and at post-injury assessment, practice effects inflate the post-injury score, masking genuine impairment. The SCAT6 provides multiple alternate word lists specifically to mitigate this. Clinicians must track which word list was used at baseline and ensure a different list is used for each subsequent assessment.
Outdated Baselines
A baseline from two or more years ago may no longer be representative. Adolescent neurocognitive development, ageing-related changes, new medications, and changes in training status all affect performance across domains. Annual re-baseline is the recommended standard (Echemendia et al., 2023). A stale baseline can lead to both false positives (if the athlete's function has improved since baseline) and false negatives (if it has declined).
Digital vs Paper-Based Baselines
Both paper-based and digital baseline testing can produce valid data. However, the practical advantages of digital platforms are significant, particularly for clinicians managing baselines across multiple athletes or teams.
Digital Advantages
- Automatic scoring eliminates calculation errors
- Baseline-to-post-injury comparison is instant
- Longitudinal trend visualisation across serial assessments
- Secure cloud storage -- accessible at sideline, clinic, or hospital
- Built-in validity checks flag anomalous scores
Paper-Based Considerations
- No technology requirements -- pen, paper, stopwatch, ruler
- Lower upfront cost for individual practitioners
- Manual scoring increases error risk
- Storage and retrieval challenges -- forms can be lost or misfiled
- No automated comparison or trend tracking
The Amsterdam Consensus Statement does not mandate digital testing, but the practical and clinical advantages are clear. For clinicians managing team baselines, the efficiency gains alone typically justify the investment. For individual practitioners, a digital platform that combines baseline storage with post-injury assessment creates a seamless clinical workflow.
Using Baseline Data Post-Injury: Reliable Change Indices
Having a baseline is only useful if you know how to interpret the difference between baseline and post-injury scores. Not every numerical change represents a clinically meaningful decline. This is where reliable change indices (RCIs) become essential.
An RCI accounts for the test-retest reliability of the assessment instrument, measurement error, and practice effects to determine whether an observed change is statistically meaningful -- that is, whether it exceeds what would be expected from normal test-retest variation alone (Broglio et al., 2007).
These thresholds are guidelines, not absolute cut-offs. Clinical judgment remains paramount. An athlete whose SAC score has dropped by 2 points but who also shows a receded NPC, elevated symptom severity, and increased mBESS errors is likely concussed despite no single domain exceeding the RCI threshold in isolation. The convergence of subthreshold changes across multiple domains is itself clinically significant.
Cost-Benefit for Clinics & Teams
The most common objection to baseline testing is cost -- both in time and money. However, when evaluated against the consequences of inadequate concussion assessment, the investment is strongly favourable.
The Investment
- Time: 15-20 minutes per athlete for a comprehensive baseline battery (symptoms, SAC, mBESS, VOMS)
- Personnel: Can be administered by trained allied health professionals, sports trainers, or nursing staff under clinical oversight
- Equipment: Minimal -- stopwatch, ruler/tape measure, SCAT6 forms (or digital platform)
The Return
- Improved diagnostic accuracy: Individualised comparison dramatically improves sensitivity and specificity of post-injury assessment versus normative data alone
- Safer return-to-play decisions: Objective evidence that the athlete has returned to their individual baseline, not just “within normal limits”
- Medicolegal protection: Documented baseline data demonstrates standard of care and provides defensible evidence for clearance decisions
- Clinical efficiency: Post-injury assessment is faster and more decisive when individual baselines are available for comparison
- Competitive advantage: For sports medicine clinics and team medical staff, baseline testing is an expected service that differentiates comprehensive providers from those offering minimum standard care
For teams, baseline testing can be offered as a bundled service alongside pre-participation medical examinations. For clinics, it can be billed as a structured assessment with appropriate Medicare or private health item numbers where applicable. The per-athlete cost is modest; the clinical and medicolegal value is substantial.
References
- Broglio, S. P., Macciocchi, S. N., & Ferrara, M. S. (2007). Sensitivity of the concussion assessment battery. Neurosurgery, 60(6), 1050-1058.
- McCrea, M., Barr, W. B., Guskiewicz, K., Randolph, C., Marshall, S. W., Cantu, R., ... & Kelly, J. P. (2005). Standard regression-based methods for measuring recovery after sport-related concussion. Journal of the International Neuropsychological Society, 11(1), 58-69.
- McCrea, M., Guskiewicz, K. M., Marshall, S. W., Barr, W., Randolph, C., Cantu, R. C., ... & Kelly, J. P. (2003). Acute effects and recovery time following concussion in collegiate football players. JAMA, 290(19), 2556-2563.
- Covassin, T., Elbin, R. J., Stiller-Ostrowski, J. L., & Kontos, A. P. (2009). Immediate post-concussion assessment and cognitive testing (ImPACT) practices of sports medicine professionals. Journal of Athletic Training, 44(6), 639-644.
- Echemendia, R. J., et al. (2023). Sport Concussion Assessment Tool - 6th Edition (SCAT6). British Journal of Sports Medicine, 57(11), 622-631.
- Mucha, A., Collins, M. W., Elbin, R. J., Furman, J. M., Troutman-Enseki, C., DeWolf, R. M., ... & Kontos, A. P. (2014). A brief Vestibular/Ocular Motor Screening (VOMS) assessment to evaluate concussions. American Journal of Sports Medicine, 42(10), 2479-2486.
- Erdal, K. (2012). Neuropsychological testing for sports-related concussion: how athletes can sandbag their baseline testing without detection. Archives of Clinical Neuropsychology, 27(5), 473-479.
- Galetta, K. M., Brandes, L. E., Maki, K., Dziemianowicz, M. S., Laudano, E., Allen, M., ... & Balcer, L. J. (2011). The King-Devick test and sports-related concussion: study of a rapid visual screening tool in a collegiate cohort. Journal of the Neurological Sciences, 309(1-2), 34-39.
- Patricios, J. S., et al. (2023). Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport -- Amsterdam, October 2022. British Journal of Sports Medicine, 57(11), 695-711.
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