special subjects
Overview of Exercise
Aerobic Exercise
Aerobic (cardiovascular) exercise is continuous, rhythmic physical activity. Exertion occurs at a level that can be supported by aerobic metabolism (although brief periods of more intense exertion triggering anaerobic metabolism may be interspersed) continuously for at least 5 minutes as a starting point and is increased slowly over time. Aerobic conditioning increases maximal oxygen uptake and cardiac output (mainly an increase in stroke volume), decreases resting heart rate, and reduces cardiac and all-cause mortality; however, too much activity causes excessive wear on the body (eg, cartilage wear contributing to Osteoarthritis (OA) ) and increases cellular oxidation and free radicals. Examples of aerobic exercise include running, jogging, fast walking, swimming, bicycling, rowing, kayaking, skating, cross-country skiing, and using aerobic exercise machines (eg, treadmill, stair-climbing, or elliptical machines). Certain team sports such as basketball and soccer can also provide vigorous aerobic exercise but may stress knees and other joints. Recommendations should be based on patient preferences and abilities. or as hard as the person can exert for that time while maintaining proper body mechanics). This regimen, known as high-intensity interval training (HIIT), is more stressful on joints and tissues and so should be done infrequently (eg, initially once a week to allow the body to adapt to the strain, and then increase up to 2 or 3 times a week) or alternated with more conventional low- to moderate-intensity training. Although exercise decreases overall cardiovascular risks, risk of atrial fibrillation appears to be increased in endurance athletes, particularly those younger than age 55 ( Aerobic exercise references , Resistance training machines or free weights can be used for aerobic exercise provided that a sufficient number of repetitions are done per set, rest between sets is minimal (near zero to 60 seconds), and intensity of effort is relatively high. In circuit training, the large muscles (of the legs, hips, back, and chest) are exercised followed by the smaller muscles (of the shoulders, arms, abdomen, and neck). Circuit training for only 15 to 20 minutes can benefit the cardiovascular system more than jogging or using aerobic exercise machines for the same amount of time because the more intense workout results in a greater increase in heart rate and oxygen uptake. This combined aerobic and resistance training enhances muscular endurance of all the involved muscles (ie, not just the heart). can be approximated by direct measurement ( Aerobic exercise references , Alternatively, the Karvonen formula can be used to calculate target heart rate ( Aerobic exercise references ): These formulas are based on the general population and may not provide accurate targets for people at the extremes of physical fitness (ie, highly trained athletes or physically deconditioned patients). In such people, metabolic or VO2testing may provide more accurate information. Chronologic age should be distinguished from biologic age. People of any age who are less accustomed to aerobic exercise (less conditioned) will reach their target heart rate much sooner and with less effort, necessitating briefer exercise periods, at least initially. People with obesity may be deconditioned and must move a larger body weight, thus causing the heart rate to increase much faster and to a greater extent with less vigorous activity than it does in thinner people. Patients with medical disorders or who are taking certain drugs (eg, beta-blockers) may also have a modified relationship between age and heart rate. A safe starting point for these patients may be 50 to 60% of the age-based target heart rate. These targets can be increased based on patient tolerance and progress. 1.Newman W, Parry-Williams G, Wiles J, et al: Risk of atrial fibrillation in athletes: a systematic review and meta-analysis.Br J Sports Med55(21):1233-1238, 2021. doi:10.1136/bjsports-2021-103994 2.Rao P, Shipon D: Latest in Cardiology. Atrial Fibrillation in Competitive Athletes, American College of Cardiology. 2019. 3.Robergs RA, Landwehr R: The surprising history of the “HRmax=220-age” equation.Am J Soc Exercise Physiol5(2), 2002. 4.Karvonen J, Vuorimaa T: Heart rate and exercise intensity during sports activities. Practical application.Sports Med5(5):303-311, 1988. doi: 10.2165/00007256-198805050-00002 