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“Consensus Guidelines for Physical Activity and Public Health from the American Heart Association and American College of Sports Medicine call for at least 150 minutes per week of moderate ET or 75 minutes per week of vigorous ET in the general adult population. Those guidelines also suggest that larger doses of ET may be necessary in some groups, such as those with or at risk for CHD (30 to 60 minutes daily), adults trying to prevent the transition to overweight or obesity (45 to 60 minutes per day), and formerly obese individuals trying to prevent weight regain (60 to 90 minutes per day). These guidelines also caution that high-intensity ET increases risk of musculoskeletal injuries and adverse CV events” (*Haskell et al., 2007; La Gerche, Robberecht, & Kuiperi, 2010).
The effects of bed rest and the supine position are illustrated in Figure II.1.
The effects of bed rest deconditioning develop rapidly and may take weeks or months to reverse. All people confined to bed are at risk for activity intolerance as a result of bed rest-induced deconditioning.
Early mobility has been linked to decreased morbidity and mortality as inactivity has a profound adverse effect on the brain, skin, skeletal muscle, pulmonary, and cardiovascular systems (Zomorodi, Darla Topley, & McAnaw, 2012).
Delirium, decubitus ulcers, muscular atrophy, and deconditioning may occur in the immobile patient, as a result of atelectasis, pneumonia, orthostatic hypotension, and deep venous thrombosis (Zomorodi et al., 2012).
Endurance is the ability to continue a specified task; fatigue is the inability to continue a specified task. Conceptually, endurance and fatigue are opposites. Nursing interventions, such as work simplification, aim to delay task-related fatigue by maximizing efficient use of the muscles that control motion, movement, and locomotion.
The ability to maintain a given level of performance depends on personal factors, strength, coordination, reaction time, alertness, and motivation, and on activity-related factors, frequency, duration, and intensity.
“Emerging data suggest that chronic training for and competing in extreme endurance events such as marathons, ultramarathons, ironman distance triathlons, and very long distance bicycle races, can cause transient acute volume overload of the atria and right ventricle, with transient reductions in right ventricular ejection fraction and elevations of cardiac biomarkers, all of which return to normal within 1 week. Over months to years of repetitive injury, this process, in some individuals, may lead to patchy myocardial fibrosis, particularly in the atria, interventricular septum, and right ventricle, creating a substrate for atrial and ventricular arrhythmias” (O’Keefe et al., 2012, p. 588).
Children at special risk for activity intolerance include those with respiratory conditions, cardiovascular conditions, anemia, and chronic illnesses (Hockenberry & Wilson, 2015).
“It is important to recognize that most children with congenital heart defects are relatively sedentary and that the physical and psychosocial health benefits of physical activity are important for this population, which is at risk for exercise intolerance, obesity, and psychosocial morbidities. Therefore, counseling to encourage daily participation in appropriate physical activity should be a core component of every child/parent encounter” (Longmuir et al., 2013).
Research shows that supervised exercise training at moderate intensity is safe and produces significant beneficial changes in hemodynamics and exercise time in children with cardiac disease (*Balfour, 1991; Longmuir et al., 2013).
Decreased cardiac output in older adults has been attributed to disease-related, not age-related, processes (Miller, 2015). Fleg (*1986) found no age-related changes in resting cardiac output in a study of healthy people between 30 and 80 years of age.
Studies have demonstrated an average decline of 5% to 15% per decade in maximum oxygen consumption VO2 (max) from 25 to 75 years of age. Very athletic people have declines in VO2 max; however, it is only half of the 10% per decade decline that less athletic people exhibit. There seems to be either decreased efficiency in mobilizing blood to exercising muscles or increased difficulty for muscles to extract and use oxygen because of decreased muscle mass (Grossman & Porth, 2014).
Researchers report that exercise benefits affective (mood) experience and cognitive (processing, memory) performance in all ages (Hogan, Mata, & Carstensen, 2013).
Prolonged immobility and inactivity through self-imposed restrictions, mental status changes, or pathophysiologic changes can contribute to decreased activity tolerance (*Cohen, Gorenberg, & Schroeder, 2000; Zomorodi et al., 2012).
Decreased muscle mass leads to decreased strength, which, in turn, leads to decreased endurance. Muscle strength, which is maximal between 20 and 30 years of age, drops to 80% of that value by 65 years of age (*Cohen et al., 2000; Grossman & Porth, 2014).
Changes in elastic and collogen fibers of tendons and ligaments cause decreased flexibility and loss of mobility and stability of joints (Grossman & Porth, 2014).
Increased chest wall rigidity with aging leads to decreased lung expansion, resulting in decreased tissue oxygenation. This immediately affects activity tolerance.
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