Metabolic Health

Metabolic health is a broad term referring to the transportation, use, and storage of energy via the building up (anabolic) or breaking down (catabolic) of chemicals in the body. Transport of new (e.g. dietary) and existing (e.g., stored) fuels occurs via complex trafficking of molecular cargo via blood and lymph vessels between different organ systems. Use, or expenditure, of energy, occurs due to different processes (e.g., aerobic vs anaerobic) and acting on different kinds of energetic molecules (e.g., carbohydrates or fats). The aerobic combustion of hydrocarbons—such as carbs and fats—requires oxygen, as discussed in the previous section on the rate of whole-body oxygen consumption (VO2). Energy can also be expended at a higher rate, although less sustainably, by anaerobic processes that do not directly require oxygen. Physical activity promotes the use of molecular fuels, first within the contracting muscles themselves, that can induce a systemic exchange between tissues usually requiring transportation into and out of the blood. Storage of carbohydrates is limited in humans but importantly occurs in the liver and muscles, while fat storage has a high capacity and occurs mainly in the liver, muscles, and adipocytes (fat cells). Under the umbrella of metabolic health, cardiometabolic disease (CMD) refers to a clustering of distinct risk factors. The Consortium for Spinal Cord Medicine (CSCM) clinical practice guidelines for CMD in people with SCI focus on four main categories of metabolic health: obesity, dysglycemia, dyslipidemia, and hypertension. (See the Introduction for more details.) Importantly, the CSCM CMD guidelines recommend physical exercise as a primary treatment strategy for the management of CMD in SCI.