Your Symptoms Are Gone but Your Brain Isn't Healed: The Reaction Time Gap That Lasts 59 Days

One of the most important findings in concussion science is also one of the least known by parents and coaches: symptoms resolve well before the brain actually recovers.

The data on the gap

Most concussion patients report feeling “back to normal” within 7–14 days. But research consistently shows that objective measures of brain function — particularly reaction time and postural stability — remain impaired for much longer.

A study by Kamins et al., published in the Journal of the International Neuropsychological Society, documented reaction time deficits persisting 21 to 59 days after injury. Separate research published in the British Journal of Sports Medicine (Cavanaugh et al., 2005) found that postural sway abnormalities measured by force plates can last up to 30 days post-concussion — well beyond the window of symptom resolution.

Why this creates a dangerous window

An athlete who feels fine, reports no symptoms, and passes a symptom-based clearance protocol may still have measurable cognitive and motor deficits that increase their risk of re-injury. The 6th International Consensus Statement on Concussion (2023) specifically warns against relying on symptom resolution alone to determine recovery.

Why baseline data makes the difference

This is the single strongest argument for objective baseline testing over symptom-based clearance alone. When you have baseline data for reaction time, processing speed, and balance, you can detect deficits that the athlete themselves cannot feel and would never report. “I feel fine” is not the same as “my brain is functioning at its pre-injury level.”

Graduated return-to-play exists for a reason

This is also why return-to-play protocols — as outlined by the CDC’s HEADS UP program and the Consensus Statement — require a graduated, stepwise progression with symptom monitoring at each stage. The process isn’t just about waiting for symptoms to clear. It’s about giving the brain time to complete its metabolic recovery and verifying through objective testing that function has returned to baseline.

At Headquarters, our baseline assessments include reaction time and balance testing alongside cognitive evaluation and symptom tracking. This multi-domain approach allows clinicians to detect the “hidden” deficits that symptom-only protocols miss. Because feeling better and being better are not the same thing. For the step-by-step process, see the six-step return-to-play protocol.

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