CARE-ing for concussions: Development of the Calgary Adapted aRm Ergometer (CARE) exertion test: A physiological...

Aerobic exercise testing helps facilitate recovery post-concussion. Current protocols (Calgary Concussion Cycling Test: CCCT) are inaccessible for athletes with lower-body impairments (i.e. Para athletes). This study compared physiological parameters for a novel arm crank test, the Calgary Adapted aRm Ergometer (CARE) test, with the CCCT. Twenty non-disabled adults (10F:10M, aged 18-51) completed CCCT and CARE to volitional fatigue. Middle cerebral artery velocity (MCAv), heart rate (HR), mean arterial pressure (MAP) and end-tidal carbon dioxide ( $P_{\mathrm{ETC}{O}_2}$ ) were continuously measured throughout exertion. Bland-Altman with 95% limits-of-agreement (LoA), mean differences with effect size measurement and intraclass correlation (ICC) compared CCCT to CARE at 25%, 50%, 75% and 100% of test exertion levels. Test duration was comparable between protocols (P = 0.86). HR mean differences between CCCT and CARE ranged from 2 bpm (P = 0.45) at 25% to 8 bpm (P < 0.05) at 100% effort level (negligible-to-medium effect sizes). MCAv mean differences increased from 1.5 cm/s at 25% (P = 0.45) to 5.4 cm/s at 100% effort (P < 0.05) (small effect sizes). MAP remained stable: 4.1 mmHg at 25% (P = 0.11) and 4.8 mmHg at 100% effort (P = 0.076) (small effect sizes). $P_{\mathrm{ETC}{O}_2}$ mean differences increased until 75% effort level (2.4 to 4.9 Torr, P < 0.05, medium-to-large effect size). ICC was good-to-moderate across all measurements with 95% LoA widening with increased test intensity. The CARE test represents a promising alternative to traditional lower body exercise tests, demonstrating robust physiological responses and moderate comparability with the CCCT. CARE vs. CCCT differences likely resulted from different total muscle mass engagement between the upper and lower body.