Cardiorespiratory fitness is a measure of the body’s aerobic capacity – the ability to deliver oxygen to skeletal muscles – during sustained physical activity. A 2009 meta-analysis found that people with low cardiorespiratory fitness were 70 percent more likely to die prematurely and 56 percent more likely to experience a heart or cardiovascular disease-related event.
Researchers evaluated data from 33 studies examining connections between cardiorespiratory fitness and the risk of premature death from all causes (more than 102,000 participants) and combined heart disease and cardiovascular disease events (more than 84,000 participants). They used maximal aerobic capacity, measured in metabolic equivalent (MET) units, to estimate cardiorespiratory fitness. They grouped participants into three categories based on their cardiorespiratory fitness levels: low (<7.9 METs), intermediate (7.9-10.8 METs), and high (≥10.9 METs).
They found that for each 1-MET increase in maximal aerobic capacity (equivalent to a 1-kilometer per hour increase in running/jogging speed), the risk of death from all causes and heart disease/cardiovascular disease events. Compared to participants with high cardiorespiratory fitness, those with low cardiorespiratory fitness were 70 percent more likely to die prematurely and 56 percent more likely to experience a heart disease/cardiovascular disease event. However, even intermediate cardiorespiratory fitness conferred substantial benefits. Compared to participants with intermediate cardiorespiratory fitness, those with low cardiorespiratory fitness were 40 percent more likely to die prematurely and 47 percent more likely to experience a heart disease/cardiovascular disease event.
These findings demonstrate that having low cardiorespiratory fitness markedly increases one’s risk of dying prematurely or developing heart or cardiovascular disease. The most accurate way to assess cardiorespiratory fitness involves measuring maximal oxygen uptake, often referred to as VO2 max, during a graded exercise test in a laboratory, clinical, or research setting. However, online calculators, such as the World Fitness Level, can predict VO2 max based on various personal factors. Learn more about VO2 max and the World Fitness Level calculator in this episode featuring Dr. Martin Gibala.
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