EXERCISE TRAINING ON SKELETAL MUSCLE OXYGENATION IN CHRONIC DISEASE AND IMMOBILIZATION

Skeletal muscle oxygenation is a function of matching oxygen delivery and utilization to meet the energy demands of the muscle, thus influencing exercise performance and physical capacity. Chronic conditions, including heart failure (HF), peripheral artery disease (PAD), and type 2 diabetes mellitus (T2DM), along with extended immobilization from trauma, surgery, or critical illness, impair the physiological systems regulating oxygen transport. These disorders are associated with systemic oxygen transport abnormalities and oxygen utilization inefficiency, ultimately leading to decreased exercise capacity, greater fatigability, and compromised physical function. Exercise training is a fundamental tool to alleviate these effects by promoting central and peripheral adaptations that enhance skeletal muscle oxygenation. Exercise training offers substantial potential for ameliorating functional outcomes, alleviating disease burden, and improving quality of life by targeting disease-specific deficits and the effects of disuse. This mini-review discusses the mechanisms that lead to oxygen delivery and utilization deficiencies in chronic disease and prolonged immobilization and describes the physiological adaptations associated with exercise training in combating these abnormalities. In particular, adaptations to the cardiovascular system, skeletal muscle vasculature, and mitochondrial function are central to restoring oxygen delivery and utilization. These physiological changes contribute to improved skeletal muscle oxygen consumption, reduced muscular fatigue, and greater tolerance for physical activity in both clinical and rehabilitative populations. This has important implications for clinical exercise prescription and rehabilitation practice. Understanding the specific impairments associated with different pathologies and tailoring exercise modalities accordingly may further optimize outcomes. A deeper appreciation for the interaction between disease burden, disuse, and physical training can help clinicians implement more effective, individualized rehabilitation strategies.