Aerobic Exercise

Aerobic, or endurance, exercise is an energy-requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis, dynamically linking oxygen consumption and carbon dioxide production in muscle to gas exchange at the lung. ^[1] Maximum oxygen uptake (VO2max) is the standard expression of aerobic capacity, and endurance exercise can be partitioned into intensity domains whose upper limit of moderate intensity is marked by the lactate threshold. ^[1]

Endurance training produces adaptations of the cardiorespiratory and neuromuscular systems that enhance oxygen delivery to the mitochondria and enable tighter regulation of muscle metabolism, shifting the velocity-time curve so athletes can exercise longer at a given intensity. ^[2] The four key parameters of aerobic fitness affected by endurance training are maximal oxygen uptake (VO2max), exercise economy, the lactate/ventilatory threshold, and oxygen uptake kinetics. ^[2] Regular exercise may improve muscle insulin sensitivity and is considered a key tool in the prevention and treatment of metabolic disorders, even though acute metabolic effects of exercise are mostly insulin-independent. ^[3]

In a dose-response meta-analysis of 34 randomized trials in adults with hypertension, each 30 min/week of aerobic exercise reduced systolic blood pressure by 1.78 mmHg and diastolic blood pressure by 1.23 mmHg, with the greatest reduction at 150 min/week. ^[4] In a dose-response meta-analysis of 116 randomized trials involving 6880 adults with overweight or obesity, each 30 min/week of aerobic exercise reduced body weight by 0.52 kg, waist circumference by 0.56 cm, and body fat percentage by 0.37%. ^[5] In a meta-analysis of randomized trials in patients with Alzheimer's disease, aerobic exercise significantly increased the mini-mental state examination score, whereas combined-modality analyses reached significance only for the aerobic subgroup. ^[6] In a meta-analysis of randomized trials, aerobic exercise training improved asthma control and slightly improved lung function in adults with asthma, but had no apparent effect on markers of airway inflammation

Low physical activity is a leading independent predictor of poor cardiovascular health, and exercise confers benefits across cardiovascular prevention including type 2 diabetes, hypertension, hyperlipidemia, coronary artery disease and heart failure. ^[8] High cardiorespiratory fitness mediates the neuroprotective effects of endurance exercise through improved cerebral blood flow, reduced inflammation, and enhanced neuroplasticity, mitigating age-related cognitive decline and dementia risk. ^[9]