On this episode of The Sports Engineering Podcast, we wrap up the year with Dr Janie Cournoyer by delving into one of the most challenging problems in sports medicine: diagnosing head injuries. We explore why concussions are so difficult to identify, measure, and manage, and unpack how the brain’s ability to compensate complicates both diagnosis and decision-making. We discuss how engineers and clinicians navigate the grey space between objective data and subjective symptoms, reflecting on what we can measure, what we can’t, and why understanding that gap matters.