Exercise is medicine in the 21st century – Emphasis on efficacy, dosing, and safety/toxicity

Abstract

Substantial evidence from epidemiologic and cohort studies has established the critical importance of physical activity (PA), exercise training (ET), and overall levels of cardiorespiratory fitness (CRF) in the prevention and treatment of cardiovascular diseases (CVD). In fact, low levels of CRF may be the strongest CVD risk factor and predictor of higher mortality, and many studies show that relatively fit subjects with certain disorders, such as obesity, hypertension, dyslipidemia and diabetes, have considerably better prognosis than do unfit subjects without these disorders. The role of low PA as the fundamental cause of obesity will be discussed, as well as low levels of CRF explaining the obesity paradox. The potential benefits of PA/ET and increases in CRF to protect against CVD will be discussed, especially the impact on psychological risk factors, such as depression, anxiety and hostility and overall high levels of psychosocial stress to increase mortality risk, especially in patients with established CVD, such as coronary heart disease (CHD). Even small improvements in CRF and peak VO2 can produce marked reductions in depression and psychological risk factors and lead to marked reductions in mortality risk in cohorts of CVD patients, such as CHD and heart failure. Most of the evidence indicates that the ET benefits especially occur at low doses; in fact, in our major running studies, quite low doses of running appear to produce the greatest reductions in CVD- and all-cause mortality during long-term follow-up studies. On the other hand, high doses of running may be associated with some loss of the ET/running benefits; and very high levels of ET (e.g. marathons and triathlons) are associated with potential cardiotoxicity, which will be briefly discussed. Exercise is Medicine and optimal dosing for this potentially beneficial therapy will be discussed for long-term prevention of chronic diseases, especially CVD and premature mortality.