45 (18A) The impact of exercise intensity on blood lactate in collegiate athletes with sport related concussion: a pilot study

Purpose To examine the effect of calorically matched light (Rating of Perceived Exertion [RPE]-9) and moderate (RPE-13) daily exercise on Blood Lactate (La -) and days until symptom resolution (SRA) in collegiate athletes with concussion.Methods Participants (n=10,40% female) were randomly assigned to initiate a treadmill walking protocol at an RPE-13 (n=6, 33.3% female) or RPE-9 (n=4, 50% female) within 72 hours of concussion.Initial symptom severity was assessed with the Revised Head Injury Scale at Visit 1. Blood La - (mmol) was measured before and after exercise at Visit 1 and Visit 2(SRA).Initial symptom severity and days to SRA were compared using independent t-tests.An ANCOVA compared change in La -between Groups at Visits 1 and 2, controlling for initial total symptom severity.Analyses were performed with a= 0.05.Results Although underpowered, initial symptom severity was greater in RPE-13 (32.013.1)compared with RPE-9 (16.8 8.62).Average heart rate was similar between RPE-13 (116 14.0 bpm) and RPE-9 (1039.97bpm) groups at Visit 1. RPE-13 (1318.08bpm) was significantly higher than RPE-9 (10913.0 bpm [p=0.01]) at Visit 2. Days until SRA were similar between RPE-13 (9.04.29) and RPE-9 (6.254.99)groups (p>0.05).Though not significant, change in La - between RPE-13 (1.282.06;0.021.33)and RPE-9 (-2.20 2.89; 0.570.51)at Visits 1 and 2 showed differing patterns.Conclusions Though our study was underpowered to evaluate how exercise intensity influences La -responses in collegiate athletes with concussion, both RPE-13 and RPE-9 groups achieved SRA approximately three and four days sooner than collegiate athletes, with similar symptom severity, who received standard-of-care concussion management.