Why can exercise trigger post-exertional symptom exacerbation in ME/CFS and Long Covid—and how can crashes be avoided?Physiotherapist and exercise scientist Professor Todd Davenport joins Emily Kate Stephens on Make Visible to explain why traditional exercise approaches can worsen symptoms in energy-limiting conditions. Drawing on research including the two-day cardiopulmonary exercise test (CPET), Todd explores impaired oxygen use, disrupted energy production, and why this isn’t simply deconditioning.They discuss how pacing, heart-rate monitoring, and staying below the ventilatory anaerobic threshold can help people manage activity, reduce symptom burden, and improve baseline—without triggering crashes. Gez Medinger also joins Emily to reflect on the ideas through lived experience of energy-limiting illness.