The effects of mild exercise induced dehydration on sport concussion assessment tool 3 (SCAT 3) scores: a within-subjects design.

Collins SM, Liniger MR, and Bowman TG. Int J Sports Phys Ther. 2021;16(2):511-517.
Full Text is Freely Available

Take-Home Message

Exercise-induced dehydration may negatively impact scores on the Sport Concussion Assessment Tool 3 (SCAT3).  


Exercise-induced dehydration is common among athletes during practices and competitions and negatively impacts many of the measures we use to assess a concussion (e.g., balance, reaction time, memory). Hence, there is concern that the Sport Concussion Assessment Tool 3 (SCAT3), which many clinicians use on the field, may be influenced by exercise-induced dehydration.

Study Goal

Collins, Liniger, and Bowman completed a repeated measures design to investigate the effects of exercise-induced dehydration on SCAT3 scores for neuropsychological performance.


The researchers recruited 17 recreationally active individuals (7 male, 10 female) with no history of concussion or heat-related illness. All participants first completed baseline testing, including urine sample and body mass measurements. The authors excluded a participant if they were dehydrated, based on the urine sample. Next, a participant sat for 60 minutes and drank water as needed (control session). After resting, the researchers randomized a participant to one of 2 exercise sessions, which included a 60-minute treadmill run. Each participant performed 1 session where fluids were restricted (dehydrated) and another where 1 L of fluid in 250 mL doses was required (euhydrated). After each session, participants performed a cool down,  completed the SCAT3, provided a urine sample, and had their body mass measured. Each exercise session was separated by at least 72 hours.


The researchers found that participants had worse symptom and symptom severity scores after the dehydrated session than the resting (control) session. Interestingly, participants even had slightly worse symptom scores after the euhydrated session than the control session.


Ultimately, the researchers demonstrated that exercise and hydration status could influence SCAT3 symptom and symptom severity scores. The authors noted that the difference between the euhydrated and control session might be clinically insignificant. It would be helpful to know how long it takes for scores to normalize after an athlete rehydrates. Overall, clinicians should be aware that the SCAT3, which is primarily used as a sideline concussion evaluation tool, may be impacted by dehydration. However, it would be helpful if future research could clarify whether hydration status impacts SCAT3 scores enough to change clinical decision making during a practice or competition.

Clinical Implications

Clinicians should recognize that SCAT3 scores can vary based on an athlete’s hydration status. It may be prudent to repeat the SCAT3 after an athlete rehydrates.

Questions for Discussion

Do you utilize the SCAT3 in your sideline concussion assessments? Have you considered this limitation and if so, what experiences do you have with conflicting results?

Written by: Kyle Harris
Reviewed by: Jeffrey Driban

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