Mixed

Standardized ex vivo high-resolution respirometry (HRR) measurements of mitochondrial function in permeabilized human skeletal muscle significantly underestimate in vivo metabolic rates because they are conducted at 37°C, whereas mitochondria operate at temperatures up to 10°C higher (approx. 50°C) during maximal exercise.

If you are interpreting mitochondrial function from lab tests on muscle biopsies (ex vivo), be aware that standard tests at 37°C likely underestimate true in vivo capacity. The paper suggests that mitochondrial temperature during exercise can reach ~50°C. To compare lab results with real-world metabolic performance, apply a temperature correction factor (approx. 10°C increase) to the ex vivo data.