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The mBESS Explained: Why the Modified Balance Error Scoring System Might Be Better Than the Original
Sometimes less is more — the case for mBESS over full BESS.
The Balance Error Scoring System (BESS) has been a cornerstone of concussion balance assessment since its development at the University of North Carolina Sports Medicine Research Laboratory. The modified version — mBESS — simplifies the original by eliminating the foam surface conditions, testing only on a firm surface in three stances: double leg, single leg (on the nondominant foot), and tandem (heel-to-toe).
Why simpler may be better
What makes mBESS compelling is that the simplification may actually improve clinical performance. A 2018 prospective observational study of collegiate athletes published in Concussion (PMC, 2018) found that mBESS demonstrated 71.4% sensitivity for detecting acute balance impairments the day after concussion — compared to 60.0% for the full BESS. Even more striking, mBESS detected lingering balance deficits at follow-up evaluations that had already resolved on full BESS testing.
A 2022 study examining over 600 baseline tests and 41 post-injury assessments among collegiate cheer and dance athletes found that omitting the double-leg stance — the easiest condition, where few athletes make any errors — resulted in minimal score differences with negligible clinical impact. The single-leg and tandem stances are where the clinically meaningful data lives.
Practical advantages
The mBESS offers practical advantages that matter in real-world settings: it requires no special equipment (no foam pad to carry and maintain), takes less time to administer, and according to research published in Concussion (2023), can even be performed remotely via video observation with maintained reliability — a significant advantage for telehealth concussion care.
The subjectivity limitation
The primary limitation remains subjectivity. Traditional mBESS relies on a clinician counting errors by visual observation, which introduces inter-rater variability. Research compiled in the Rehabilitation Research and Practice database (Iverson & Koehle, 2013) documents that BESS inter-rater reliability ranges from adequate to excellent (ICC = 0.57–0.85), depending on the evaluator’s training and experience. This is why instrumented versions — using force plates or smartphone accelerometers — are increasingly being adopted to add objectivity.
How we use mBESS at Headquarters
At Headquarters, we include mBESS in our standard baseline protocol and pair it with objective instrumented balance measurement when available to capture both the clinical standard and the added precision of technology-assisted assessment. For the broader comparison of balance tools, see BESS vs. mBESS vs. instrumented BESS.