Table 1. Definition and classification of mitochondrial function.

Parameter	Definition
Activity	Resting oxidative phosphorylation flux (ADP:ATP ratio) in distinct metabolic conditions
Oxidative phosphorylation capacity	Maximal ADP‐stimulated oxidative phosphorylation
Submaximal oxidative phosphorylation	In vivo non‐resting mitochondrial activity stimulated by energy depletion during standardized in vivo experiments
Plasticity	Changes of mitochondrial activity, mitochondrial content or oxidative phosphorylation capacity due to altered metabolic conditions
Coupling	The molar ratio of the yield of ATP per oxygen consumed or electrochemical coupling

ADP, adenosine diphosphate; ATP, adenosine triphosphate.