The relationship between sex, symptom severity and the risk of exercise intolerance in adolescents following sport-related concussion.
DOI:
https://doi.org/10.64255/qqc60953Keywords:
Sport-Related Concussion , Exercise Intolerance, Sex Differences, Exercise PhysiologyAbstract
Introduction: Exercise intolerance is a risk factor for prolonged recovery following sport-related concussion (SRC) in adolescents. Evidence suggests adolescent females are at increased risk of exercise intolerance and report higher symptom severity compared to males. Thus, this study examined if the association between sex and risk of exercise intolerance was either moderated or mediated by symptom severity.
Methods: Within 14-days of SRC, adolescents participating in the pan-Canadian SHRed Concussions study reported SCAT5 symptom severity score (SSS) and completed a Buffalo Concussion Treadmill Test (BCTT). The BCTT was terminated following a 3/10 increase in concussion symptoms (exercise intolerant) or volitional fatigue (>180bpm, >18/20 rating of perceived exertion; exercise tolerant). Moderation of sex effects on exercise intolerance risk by SSS were evaluated by likelihood ratio tests. Mediation by SSS was evaluated using the parametric g formula with bootstrap standard errors.
Results: 281 adolescents (126 male, 155 female) were included. 204 (100 male, 104 female) were tolerant to exercise and 77 (26 male, 51 female) were intolerant. Multivariable analysis revealed that 1 unit of square root SSS higher symptom severity was associated with increased risk (RR=1.16; 95% CI: 1.06, 1.27) while sex was associated with non-significant increased risk (RR=1.36; 95% CI: 0.90, 2.05) of exercise intolerance. Moderation assessed via likelihood ratio test was not significant (X2(1)=1.50, p=0.221). Mediation results showed significant indirect effects of sex through SSS (RR=1.131; 95% CI: 1.035, 1.272), accounting for 28% of the estimated total effects (RR=1.570; 95% CI: 0.986, 2.418) while direct effects, which explained a larger proportion of total effects (72%) were not significant (RR=1.36; 95% CI: 0.90, 2.05).
Conclusion: Potential sex differences in the risk of exercise intolerance following SRC are partially explained by differences SSS. The larger yet imprecisely estimated direct effects of sex on risk of exercise intolerance highlighting the presence of additional pathways which are distinct from symptomology and warrant further investigation.
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