Objective: Cognitive exertional effects (CEE; [increasing symptoms]) occur in response to cognitive activities after mild traumatic brain injury (mTBI). These effects can be quantified using the Exertional Effects Index (EEI). Previously, using standardized regression-based (SRB) change statistics, we established cutoff values on the EEI that differentiate individuals with and without mTBI. This study assesses the relation between exertional SRB change scores and other measures of concussion assessment and investigates potential demographic or injury-related predictors of CEE. Participants and Methods: Uninjured (n=2007) and mTBI (n=472) participants (5-18y) rated four symptoms (headache, fatigue, concentration problems, irritability) on 0-10 scales before and after cognitive testing, producing the EEI and SRB change scores. We examined the relation between the exertion change scores and cognitive test performance on age-appropriate versions of ImPACT and symptom ratings with the PCSI. Rates of CEE within the mTBI group were examined among demographics (age, gender, previous diagnosis, history of mTBI) and injury characteristics (LOC, amnesia, time since injury, cause of injury). Results: Correlations of exertional SRB changes scores with ImPACT performance were in the expected direction and slightly stronger in mTBI, but all r’s < |.2|. Exertional ratings were mildly correlated with PCSI ratings in older groups of mTBI children (r = .2, .3) but not 5-7 year-olds with mTBI, and correlations were only significant in the younger, uninjured children (5 -12y, p < .001, r < .2). CEE was more prevalent in females with mTBI (OR = 2.1) and in those with a history of previous mTBI (OR = 1.7). There were no significant differences in CEE rate among the other variables tested. Conclusions: CEE is quantifiable and largely independent of neurocognitive test performance and symptom ratings, and therefore is a useful additional measure of mTBI status that should be incorporated in mTBI assessment and treatment planning.