Exercise induces a number of cardiovascular and respiratory responses to occur inside the body (1). As exercise commences the demand for oxygen rises in order for the body to continue providing energy for muscular function. To do this, oxygen uptake increases linearly to match skeletal muscle demand, until maximum oxygen
consumption is reached (2). Ventilation will increase so more oxygen is being consumed and more carbon dioxide
(CO2) is offloaded; cardiac output (the product of stroke volume and heart rate) and blood
pressure will also increase to pump the required oxygen around the body (1,2). Vasodilation will also occur peripherally as blood flow to the working skeletal muscles increases in order to supply more oxygen, and remove carbon dioxide (1,2). Oxygen extraction from the arterial blood by the active muscles also increases (2). These make up the acute cardiorespiratory responses to exercise (2).
The peripheral chemoreceptors, which detect oxygen, CO2 and hydrogen ion levels going to the heart and brain, are also known to be important during exercise (3). These chemoreceptors cause increased depth of breathing in order to meet the metabolic demands of tissues during heavy exercise (3). They are responsible for compensating for the metabolic acidosis induced by exercise, as they detect the decrease in blood pH associated with lactic acid accumulation (4), as well as the increasing CO2 levels correlated with respiring muscles (5). These factors together drive