CS and chronic obstructive pulmonary disease: Low-load resistance training has also recently been found to enable structural and morphologic muscle adaptations e.g., increased muscle citrate synthase activity (CS) and hydroxyacyl-coenzyme A dehydrogenase (HADH) muscle protein levels as well as increase capillary-to-fiber ratioconsistent with an increase in the endurance capacity of the quadriceps among patients with COPD, but without a clear effect on quadriceps strength (Nyberg et al., 2021).