ABSTRACT
Understanding the normal exercise physiology of an aging individual is critical in interpreting the results of a test. This chapter focuses on those changes that affect exercise in the elderly in the muscle, cardiovascular, and pulmonary systems and discusses the challenges of identifying normal values with the confounding factors of emerging disease. First, there is a decrease in the proportion of the Type II fibers that results in a loss of strength and an anaerobic threshold that appears at a higher percentage of the overall VO2 max. In addition, there is a loss of mitochondrial efficiency leading to an increased oxygen consumption requirement for any given workload. Second, the normal aging heart develops some degree of diastolic dysfunction leading to a reduction in exercise stroke volume at higher heart rates. Third, there is a decrease in maximum heart rate with age, although the extent of this maximal heart rate reduction is highly variable among individuals of the same age. Fourth, recruitment of the peripheral vasculature is slowed with the onset of exercise, thus impairing initial perfusion and oxygen delivery at the onset of exercise. Fifth, the lungs have a minimal increase in airflow obstruction, although this is too small to impair maximum exercise capacity in normal subjects.
