BESS Balance Testing for Concussion: A Clinician's Complete Guide
The Balance Error Scoring System remains one of the most widely used and accessible tools for assessing postural stability after concussion. Here's how to administer it correctly, avoid common pitfalls, and interpret results with confidence.
What Is the BESS?
The Balance Error Scoring System (BESS) is a clinical balance assessment tool developed by Guskiewicz and colleagues in the early 2000s as a portable, cost-effective method for evaluating postural stability following concussion (Guskiewicz, 2001; Guskiewicz et al., 2001). Unlike instrumented force-plate posturography, the BESS requires no equipment beyond a piece of medium-density foam and a stopwatch, making it feasible for sideline, clinic, and field-based settings.
The full BESS protocol consists of six conditions: three stances performed on two surfaces. The three stances are double-leg (feet together), single-leg (standing on the non-dominant foot), and tandem (heel-to-toe with the dominant foot in front). Each stance is performed once on a firm surface and once on a foam pad, for a total of six 20-second trials. The foam surface eliminates reliable somatosensory input from the feet, increasing the challenge to vestibular and visual processing systems -- precisely the systems most commonly disrupted by concussion.
During each 20-second trial, the patient stands with eyes closed and hands on the iliac crests. The clinician counts the number of “errors” committed. Each condition is scored from 0 (no errors) to a maximum of 10, yielding a total BESS score ranging from 0 to 60 -- with higher scores indicating poorer balance performance.
The Six BESS Conditions
Each condition progressively challenges the sensory systems responsible for maintaining postural equilibrium. Understanding why each condition exists helps clinicians interpret patterns of deficit.
1. Double-Leg Stance -- Firm Surface
Feet together, hands on iliac crests, eyes closed, 20 seconds. The easiest condition. Provides a wide base of support on a stable surface. Errors here suggest significant postural impairment.
2. Single-Leg Stance -- Firm Surface
Standing on the non-dominant foot, contralateral hip flexed to approximately 30 degrees, eyes closed, 20 seconds. Dramatically reduces the base of support and increases demand on proprioceptive and vestibular systems.
3. Tandem Stance -- Firm Surface
Heel-to-toe position with the dominant foot in front, eyes closed, 20 seconds. Narrows the anterior-posterior base of support, challenging mediolateral stability and requiring precise vestibular integration.
4. Double-Leg Stance -- Foam Surface
Same as condition 1, but on medium-density foam. The foam disrupts somatosensory input from the plantar surface, forcing greater reliance on vestibular processing. With eyes closed and somatosensory input degraded, the vestibular system becomes the primary balance reference.
5. Single-Leg Stance -- Foam Surface
The most challenging condition. Single-leg stance on foam with eyes closed. This condition produces the highest error rates in both concussed and healthy populations. A ceiling effect is common, with many concussed patients reaching the maximum of 10 errors.
6. Tandem Stance -- Foam Surface
Heel-to-toe stance on foam with eyes closed, 20 seconds. Combines a narrowed base of support with degraded somatosensory input. Particularly sensitive to vestibular dysfunction and one of the most discriminative conditions for identifying concussion-related balance deficits.
The Evidence Base for BESS
The BESS has been studied extensively in sport-related concussion populations since its development. Understanding both its strengths and limitations is essential for appropriate clinical application.
Guskiewicz (2001) demonstrated that the BESS could detect postural instability in concussed athletes with reasonable sensitivity, particularly within the first 24-48 hours post-injury. Subsequent work by Guskiewicz et al. (2003) confirmed that BESS-detected deficits typically resolve within 3-5 days, although a subset of patients show prolonged impairment.
However, clinicians should be aware of the BESS's limitations. Bell et al. (2011) documented significant practice effects with repeated administration, and moderate inter-rater reliability (ICC ranging from 0.57 to 0.96 depending on the condition). Iverson & Koehle (2013) reported that approximately 30% of healthy athletes score in the “abnormal” range on a single administration, highlighting the critical importance of baseline testing for accurate interpretation.
How to Administer the BESS: Step-by-Step
Standardised administration is essential for reliable scoring. The following protocol should be followed consistently for both baseline and post-injury assessments.
Step 1: Prepare the Environment
Use a flat, firm surface (not carpet) for the firm-surface conditions. Place the foam pad (medium-density, approximately 50 cm x 40 cm x 6 cm) on the same flat surface. Ensure the testing area is safe -- position yourself or a colleague nearby to prevent falls. Remove shoes and socks.
Step 2: Determine the Non-Dominant Foot
Ask the patient: “Which foot would you kick a ball with?” The opposite foot is the stance leg for single-leg conditions. The dominant foot goes in front for tandem stance.
Step 3: Instruct the Patient
For each condition, clearly instruct: “Place your hands on your hips, close your eyes, and try to maintain this position as still as possible for 20 seconds. If you move out of position, return to the starting position as quickly as possible.” Demonstrate the stance before each trial.
Step 4: Time and Score Each Trial
Begin timing when the patient closes their eyes. Count errors silently for 20 seconds. Record the error count for each condition. If the patient cannot maintain the position for the full 20 seconds and commits more than identifiable errors, assign the maximum score of 10 for that condition.
Step 5: Progress Through All Six Conditions
Administer all three stances on the firm surface first (double-leg, single-leg, tandem), then repeat all three on the foam surface. Allow the patient a brief moment to assume each new position. No rest period is required between conditions.
BESS Error Types: What Counts as an Error
Accurate error identification is the single most important skill for reliable BESS administration. The following six error types are counted during each 20-second trial:
- Hands lifted off iliac crests
Any movement of the hands away from the hips, even momentarily. This is the most frequently debated error -- brief adjustments count.
- Opening eyes
Any opening of the eyes during the 20-second trial. Instruct the patient to keep eyes closed throughout and reclose immediately if opened.
- Step, stumble, or fall
Any step away from the testing position, including touching down the non-stance foot in single-leg stance. A stumble that is corrected without a step does not count, but any foot movement that breaks contact with the original position does.
- Hip abduction greater than 30 degrees
Moving the hip into abduction beyond 30 degrees from the neutral position. This is a compensatory strategy to widen the base of support. Applies primarily to single-leg stance conditions.
- Forefoot or heel lift
Lifting the forefoot or heel off the testing surface. In double-leg and tandem stances, this includes any toe or heel elevation. Subtle forefoot lifts are commonly missed by inexperienced raters.
- Remaining out of the testing position for more than 5 seconds
If the patient moves out of position and does not return within 5 seconds, this counts as an additional error. The clock continues running -- the trial is not restarted.
Critical scoring rule: Only one error is counted per observable deviation, regardless of how many error types occur simultaneously. For example, if a patient stumbles and simultaneously lifts their hands off the iliac crests, this counts as one error, not two. However, if these occur as separate, sequential events, each is counted independently. The maximum score for any single condition is 10.
Common Scoring Pitfalls & Tips
The most common source of error in BESS assessment is not the patient -- it's the rater. Inter-rater reliability studies consistently show that clinician variability is the primary limitation of the BESS (Bell et al., 2011). The following pitfalls are the most frequently encountered.
Pitfall 1: Inconsistent Foam Pads
Different foam densities produce different error rates. Using a different foam pad for post-injury testing than for the baseline renders comparison unreliable. Standardise the foam pad across all assessments -- the Airex Balance Pad is the most commonly validated option in the literature.
Pitfall 2: Counting Multiple Simultaneous Errors
As noted above, a single observable deviation counts as one error regardless of how many error criteria it satisfies. Clinicians who count each criterion separately will systematically over-score patients. Practice with video examples to calibrate your counting.
Pitfall 3: Missing Subtle Forefoot Lifts
Forefoot and heel lifts are the most commonly missed errors, particularly during foam conditions where the surface deformation can obscure the movement. Position yourself at ground level and observe the feet directly during foam trials.
Pitfall 4: Testing Fatigue
Guskiewicz et al. (2003) noted that fatigue and exercise can significantly increase BESS error scores in healthy athletes. Do not administer the BESS immediately after physical exertion. At baseline, test before or well after training. Post-injury, ensure the patient is rested and not in acute symptom exacerbation.
Pitfall 5: Ignoring Practice Effects
Bell et al. (2011) demonstrated significant practice effects across serial BESS administrations. Patients tested multiple times will improve their scores independent of genuine recovery. Account for this when interpreting serial assessments by using reliable change indices rather than raw score differences where possible.
The Importance of Baseline Testing
Iverson & Koehle (2013) provided some of the most compelling evidence for why baseline BESS testing is not optional -- it is essential. Their analysis revealed that approximately 30% of healthy, non-concussed athletes produce BESS scores that would be classified as “abnormal” when compared to population-based normative data. This means that relying on normative cut-offs alone will produce an unacceptably high false-positive rate.
Individual variability in postural control is influenced by numerous factors: ankle and knee injury history, musculoskeletal conditions, vestibular history, fatigue, footwear habits, and even the sport itself. A rugby forward may have a very different baseline BESS profile to a gymnast, even though both are “healthy.”
Pre-season baseline BESS testing should be conducted under standardised conditions: the same foam pad, the same surface, the same instructions, and the same rater where possible. This baseline becomes the individual's reference point against which post-injury scores are compared. A change of 5 or more points from baseline on the total BESS score is generally considered clinically meaningful (Guskiewicz et al., 2001), although reliable change indices provide more statistically robust thresholds.
For organisations managing baseline testing programs, digital platforms that store individual baselines alongside SCAT6 data streamline this process and reduce the risk of lost paper records.
Interpreting BESS Results in Clinical Context
The BESS should never be used as a standalone diagnostic tool for concussion. It is one component of a multimodal assessment battery that includes symptom evaluation, cognitive screening, and clinical examination. However, when interpreted correctly, the BESS provides valuable information about the integrity of the postural control system.
Acute assessment (0-48 hours post-injury):BESS is most sensitive in the acute phase. Guskiewicz (2001) reported that balance deficits are typically most pronounced within the first 24 hours. A total BESS score that is elevated by 5 or more points compared to the individual's baseline provides objective evidence of postural impairment consistent with concussion. However, a normal BESS score does not rule out concussion -- balance may be preserved while other domains (cognitive, symptom) are impaired.
Serial monitoring (Day 3-14): Most concussion-related balance deficits resolve within 3-5 days (Guskiewicz et al., 2003; McCrea et al., 2003). Serial BESS testing can track this recovery trajectory. Persistent elevation beyond 7-10 days warrants further investigation and may indicate vestibular pathology requiring specialist referral.
Return-to-play clearance: BESS scores should return to baseline (or within the reliable change interval) before an athlete progresses through the final stages of the stepwise return-to-play protocol. Balance testing under dual-task conditions (performing a cognitive task while maintaining stance) may provide additional sensitivity for detecting residual deficits that are masked by standard BESS administration.
Pattern analysis: Examining which conditions produce the most errors can guide clinical reasoning. Disproportionate errors on foam conditions relative to firm-surface conditions suggest vestibular system involvement. Disproportionate errors on single-leg conditions may reflect peripheral musculoskeletal factors rather than central concussion-related impairment.
mBESS vs Full BESS: When to Use Which
The modified BESS (mBESS) is a shortened version that includes only the three firm-surface conditions: double-leg, single-leg, and tandem stance -- all performed on a firm surface with eyes closed. The mBESS eliminates the foam pad entirely, making it even more portable and practical for sideline use.
The mBESS was adopted as the balance assessment component of the SCAT6 (Sport Concussion Assessment Tool, 6th edition) and is therefore the version most commonly encountered in sport-related concussion protocols. Its total score ranges from 0 to 30.
| Feature | Full BESS | mBESS (SCAT6) |
|---|---|---|
| Conditions | 6 (3 stances x 2 surfaces) | 3 (3 stances, firm surface only) |
| Equipment needed | Foam pad + stopwatch | Stopwatch only |
| Score range | 0-60 | 0-30 |
| Time to administer | ~5 minutes | ~2-3 minutes |
| Vestibular sensitivity | Higher (foam challenges vestibular system) | Lower (no foam conditions) |
| Best use case | Clinic/office assessment, research | Sideline assessment, SCAT6 |
The trade-off is clear: the mBESS sacrifices the foam conditions that are most sensitive to vestibular dysfunction in favour of portability and speed. For sideline assessment, the mBESS within the SCAT6 is the appropriate choice. For comprehensive office-based follow-up using the SCOAT6, clinicians should consider administering the full BESS (with foam) to maximise sensitivity, particularly when vestibular involvement is suspected.
Importantly, mBESS scores and full BESS scores are not interchangeable. If a baseline was conducted using the full BESS, post-injury comparison should ideally use the full BESS. If only mBESS baseline data is available, compare against mBESS post-injury scores only.
Integration with SCAT6 & SCOAT6
The mBESS is embedded within Step 5 of the SCAT6 as the “Modified Balance Examination.” It is administered after symptom evaluation, cognitive screening (SAC), and neurological examination. Within the SCAT6, the mBESS provides one component of a multimodal snapshot of concussion-related impairment.
In the SCOAT6 (Sport Concussion Office Assessment Tool, 6th edition), balance assessment is similarly integrated but within a more comprehensive office-based evaluation that includes vestibular-ocular motor screening (VOMS), detailed cognitive testing, and clinical examination. The SCOAT6 allows for either mBESS or full BESS administration depending on clinical resources and the assessment context.
Key integration principles:
- SCAT6 (sideline): Use the mBESS as part of the structured SCAT6 protocol. Record the total mBESS score (0-30) and compare to baseline where available.
- SCOAT6 (office): Consider the full BESS for enhanced vestibular sensitivity. Integrate balance findings with VOMS, symptom trajectory, and cognitive performance for a holistic clinical picture.
- Serial monitoring: Track mBESS or BESS scores longitudinally alongside other SCAT6/SCOAT6 domains. Balance recovery that lags behind symptom resolution may indicate vestibular pathology warranting specialist referral.
- Return-to-play: Balance normalisation (return to baseline) is a necessary but not sufficient criterion for clearance. It must be considered alongside symptom resolution, cognitive recovery, and successful completion of the stepwise exercise protocol.
Digital assessment platforms that integrate BESS/mBESS scoring with SCAT6 and SCOAT6 data provide the most efficient workflow for longitudinal tracking, allowing clinicians to visualise balance recovery alongside symptom, cognitive, and vestibular-ocular domains in a single record.
References
- Guskiewicz, K. M. (2001). Postural stability assessment following concussion: one piece of the puzzle. Clinical Journal of Sport Medicine, 11(3), 182-189.
- Guskiewicz, K. M., Ross, S. E., & Marshall, S. W. (2001). Postural stability and neuropsychological deficits after concussion in collegiate athletes. Journal of Athletic Training, 36(3), 263-273.
- Guskiewicz, K. M., McCrea, M., Marshall, S. W., Cantu, R. C., Randolph, C., Barr, W., ... & Kelly, J. P. (2003). Cumulative effects associated with recurrent concussion in collegiate football players: the NCAA Concussion Study. JAMA, 290(19), 2549-2555.
- 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: the NCAA Concussion Study. JAMA, 290(19), 2556-2563.
- Bell, D. R., Guskiewicz, K. M., Clark, M. A., & Padua, D. A. (2011). Systematic review of the Balance Error Scoring System. Sports Health, 3(3), 287-295.
- Iverson, G. L., & Koehle, M. S. (2013). Normative data for the Balance Error Scoring System in adults. Rehabilitation Research and Practice, 2013, 846418.
- Echemendia, R. J., et al. (2023). Sport Concussion Assessment Tool -- 6th Edition (SCAT6). British Journal of Sports Medicine, 57(11), 622-631.
- 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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