Minimal Detectable Change Scores and Factors Associated With Dynamic Exertion Test (EXiT) Performance After Sport-Related Concussion.

Abstract

Background: Factors associated with performance outside of a normative range on dynamic exertion test (EXiT) after sport-related concussion (SRC) remain unknown. This study examined the role of demographic and medical history factors on performance using minimal detectable change (MDC) cutoff scores in athletes being cleared to return to sport (RTS) from SRC.

Hypothesis: Older age, being female, and body mass index (BMI) ≥50th percentile would be associated with worse EXiT performance and with increased likelihood of falling outside the normative MDC score range.

Study design: Cross-sectional.

Level of evidence: Level 3.

Methods: Demographic factors, physiological metrics, performance metrics, symptoms, and ratings of perceived exertion were collected from 55 participants (age, 16.5 ± 2.3 years, 31.5% female) initially evaluated within 14 days of SRC who completed EXiT at medical clearance for RTS. Chi-square analyses, logistic and ordinal regressions, and 1-way analyses of variance examined factors associated with EXiT performance.

Results: Most participants fell within the MDC score range on aerobic (71.2-100%), dynamic (75.8-100%), and change-of-direction (36.5-98.0%) tasks, and symptoms (96.2-100%). Older age was associated with better performance on Box Drill Shuffle (P < 0.01) and lower heart rate (HR) outcomes after Ball Toss (P = 0.04), Box Drill Shuffle (P < 0.01), Box Drill Carioca (P = 0.04), and Pro Agility (P < 0.01). Greater BMI was associated with higher HR_%max after Ball Toss (P < 0.01) and worse posttreadmill aerobic performance (P < 0.01). Motion sickness history was associated with longer Zig Zag completion time (P = 0.036).

Conclusion: Most athletes presenting for clearance from concussion performed within MDC score ranges on EXiT metrics.

Clinical relevance: EXiT is accurate and effective in assessing response to dynamic exertion after SRC, and MDC scores can inform RTS decisions. Clinicians should consider age, BMI, and history of motion sickness when assessing EXiT performance.