There are numerous sources from which to obtain information on training for endurance in athletes and healthy young people and for individuals with chronic diseases such as coronary heart disease, diabetes, and others.2-4 Using the most recent research, the American College of Sports Medicine (ACSM) published basic guidelines for many of the more common chronic conditions.2-4 This chapter uses information from these well-known sources to demonstrate that the physical therapist can use aerobic-type activity when working with either healthy individuals or patients with a variety of conditions. In addition, some fundamental information about cardiovascular and respiratory parameters in children and the elderly, as well as the young or middle-aged adult, is presented so the physical therapist can be prepared to treat individuals of all ages.
Physical activity as defined by ACSM2 and the Centers for Disease Control and Prevention (CDC)6 is "any bodily movement produced by the contraction of skeletal muscles that result in a substantial increase over resting energy expenditure."
Exercise is any planned and structured physical activity designed to improve or maintain physical fitness.
Fitness is a general term used to describe the ability to perform physical work. Performing physical work requires cardiorespiratory functioning, muscular strength and endurance, and musculoskeletal flexibility. Optimum body composition is also included when describing fitness.
To become physically fit, individuals must participate regularly in some form of physical activity that uses large muscle groups and challenges the cardiorespiratory system. Individuals of all ages can improve their general fitness status by participating in activities that include walking, biking, running, swimming, stair climbing, cross-country skiing, and/or training with weights.
Fitness levels can be described on a continuum from poor to superior based on energy expenditure during a bout of physical work.11,12 These ratings are often based on direct or indirect measurement of the body's maximum oxygen consumption. Oxygen consumption is influenced by age, gender, heredity, inactivity, and disease.
Maximum Oxygen Consumption
Maximum oxygen consumption (VO2 max) is a measure of the body's capacity to use oxygen.2,4,11,12 It is usually measured when performing an exercise that uses many large muscle groups such as swimming, walking, and running. It is the maximum amount of oxygen consumed per minute when the individual has reached maximum effort. It is usually expressed relative to body weight, as milliliters of oxygen per kilogram of body weight per minute (mL/kg per minute). It is dependent on the transport of oxygen, the oxygen-binding capacity of the blood, cardiac function, oxygen extraction capabilities, and muscular oxidative potential.