Exercise in the fight against thrombosis: friend or foe?

Thrombosis is a major cause of morbidity and mortality in Western countries and is associated with a range of chronic diseases such as cardiovascular disease, renal disease, diabetes, and various autoimmune conditions. Improved health care and approaches to the treatment of disease are leading to aging populations that will probably result in an increase in the incidence of thrombosis and associated manifestations over the next few decades. Adopting a physically active lifestyle through regular exercise has been proposed to lower the risk of developing thrombosis. Indeed, it has been demonstrated that exercise is beneficial for health, although there is inconsistent data from studies investigating the effect of exercise on the risk of thrombosis, with reports of both increased and decreased risk across a variety of cohorts. Studies in this area are difficult to critique due to the variety of confounders such as age, body composition, fitness level, underlying disease and treatment, as well as exercise intensity, frequency, duration, and energy expenditure. In younger individuals and those with chronic conditions such as cardiovascular and kidney disease, there is evidence that physical activity is beneficial for the lowering of thrombotic risk, whereas in older individuals the risk is more likely to be unchanged or increased. This review will explore whether exercise is a "friend" or "foe" in lowering the risk of thrombosis. It will also discuss whether elite athletes have a lower risk of thrombosis and whether exercise may help to reduce thrombotic risk in individuals with chronic disease.