Comparison of the Buffalo Concussion Treadmill Test With a Physiologically Informed Cycle Test: Calgary Concussion Cycle Test.

Background: Sport-related concussions are a complex injury requiring multifaceted assessment, including physical exertion. Currently, concussion testing relies primarily on a treadmill-based protocol for assessing exertion-related symptoms in persons after concussion. This study compared a modified cycle protocol (Calgary Concussion Cycle Test [CCCT]) with the clinically adopted standard, the Buffalo Concussion Treadmill Test (BCTT), across multiple physiological parameters.

Hypothesis: Treadmill and cycle matched workload protocols would produce similar results for cerebral blood velocity, mean arterial pressure (MAP), and end-tidal carbon dioxide partial pressure (P_ETCO₂), but heart rate (HR) and oxygen consumption (VO₂) would be higher on the treadmill than the cycle modality.

Study design: Crossover study design.

Level of evidence: Level 3.

Methods: A total of 17 healthy adults (8 men, 9 women; age, 26 ± 3 years; body mass index, 23.8 ± 2.7 kg/m²) completed the BCTT and CCCT protocols, 7 days apart in a randomized order. During both exertional protocols, the physiological parameters measured were middle cerebral artery mean blood velocity (MCAv), MAP, P_ETCO₂, VO₂, and HR. Analysis of variance with effect size computations, coefficient of variation, and Bland-Altman plots with 95% limits of agreement were used to compare exercise tests.

Results: The BCTT and CCCT produced comparable results for both male and female participants with no significant differences for average MCAv, MAP, and P_ETCO₂ (all P > 0.05; all generalized eta squared [η²_G] < 0.02 [negligible]; P value range, 0.29-0.99) between stages. When accounting for exercise stage and modality, VO₂ (P < 0.01) and HR (P < 0.01) were higher on the treadmill compared with the cycle. Aside from the final few stages, all physiology measures displayed good-to-excellent agreeability/variability.

Conclusion: The CCCT was physiologically similar to the BCTT in terms of MCAv, P_ETCO₂, and MAP; however, HR and VO₂ differed between modalities.

Clinical relevance: Providing a cycle-based modality to exertional testing after injury mayincrease accessibility to determine symptom thresholds in the future.