Sports Medicine Research: In the Lab & In the Field: Ruler-Drop Test Susceptible to Practice Effects in Assessing Head Injuries (Sports Med Res)
Friday, November 7, 2014

Ruler-Drop Test Susceptible to Practice Effects in Assessing Head Injuries

Practice effects associated with repeated assessment of a clinical test of reaction time for head injuries

Del Rossi G, Malaguti A, Del Rossi S. J Athl Train. May 2014; 49(3): 356-359. DOI: 10.4085/1062-6059-49.2.04.

Take Home Message: Before establishing baseline measurements, participants should complete at least one practice session when performing the ruler-drop test due to practice effects.
           
Athletes who have sustained a head injury experience diminished reaction time and cognitive function such as memorization.  While there are computer-based programs to assess reaction time, the ruler-drop test has shown similar reliability and is a less expensive option, comparatively. Information from the assessment of reaction time can later be used in return to play procedures and help clinicians determine the likelihood that an athlete has sustained a head injury.  Del Rossi and colleagues tried to determine if the ruler-drop test was susceptible to practice effects by comparing whether reaction time improved over trials due to increased familiarity with the test and procedures.  Forty-three participants, 21 men and 22 females ranging between ages 19 to 24 years old volunteered for this study. The testing procedures consisted of 10 sessions administered two times per week for five weeks with 10 attempts in each session.  The three fastest and slowest reaction times were thrown out and an average of the four remaining times were calculated.  One important aspect of this study compared to other studies using a ruler-drop test was that the ruler was hidden from view when dropped.  This simple method cuts down on the ability of the participant to predict when the ruler would drop, creating more realistic results.   The authors confirmed that participants improve after repeated sessions of the ruler-drop test, most notably during the first and second sessions with a decrease in reaction time by 7 milliseconds and 13 milliseconds overall from session 1 through 10. 
           
The findings in this study are significant in confirming that the ruler drop test is susceptible to a practice effect after repeated sessions.  This test is important because it allows clinicians to utilize another tool in assessing head injuries both in the clinic and on the sidelines.  To negate the practice effects of the ruler-drop test, multiple attempts and sessions were completed and the outliers were thrown out in each session.  While the test was performed at 10 sessions, there were no significant differences after the first session.  When performing baseline assessments that authors recommend doing at least one test session before establishing true baseline values.  We also need to be careful to notice if an athlete intentionally reacts slower than they can during the baseline evaluation since this could influence how we interpret the results post concussion.  Overall, when we use the ruler-drop test in the clinical setting the authors suggest we allow the participant to practice and we may want to consider hiding the ruler and/or excluding the slowest and fastest times from the testing session

Questions for Discussion: Is it feasible to administer the ruler-drop test on the sideline to determine reaction time? How long do you think the practice effects last when administering the ruler-drop test?

Written by: Brad Duong & Eva Martinez
Reviewed by: Kim Pritchard

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Del Rossi, G., Malaguti, A., & Del Rossi, S. (2014). Practice Effects Associated With Repeated Assessment of a Clinical Test of Reaction Time Journal of Athletic Training, 49 (3), 356-359 DOI: 10.4085/1062-6059-49.2.04

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