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Upon completion of this chapter the student should be able to demonstrate the following competencies and proficiencies concerning aerobic conditioning:

  • Understand the effects of oxidative training on:

    • Heart rate

    • Respiration rate

    • The muscular system

    • The cardiovascular system

  • Describe the energy systems

  • Determine target heart rate

  • Know the effects of deconditioning on the patient

  • Understand training variables in special populations

  • Understand the different training programs

  • Design a training program


A primary concern of most athletes during rehabilitation is staying in shape for their sport. However, the word "shape" takes on different meanings depending on the athlete and the sport. Cardiorespiratory endurance, flexibility, muscular endurance, muscular strength, and muscular power are components of fitness that a health care professional should consider when developing a plan for an injured athlete. This chapter will address the cardiorespiratory system (CRS) or aerobic/oxidative system, effects of exercise on the CRS, maintenance of the CRS, and muscular endurance in the injured athlete. Flexibility, muscular strength, and muscular power are addressed in Chapters 5, 7, and 9.


The CRS is composed of four components: (1) heart, (2) lungs, (3) blood vessels, and (4) blood. These four components work together as the heart takes the deoxygenated blood from the venous system to the lungs, where carbon dioxide is replaced with oxygen (pulmonary circulation). The oxygenated blood is then pumped from the left ventricle into the arterial system, where it is carried to the body's tissues (system circulation) (Fig. 11-1).1–3

Figure 11-1.

The human circulatory system.

Cardiorespiratory endurance or aerobic power can be defined as the capacity of the heart, blood vessels, and lungs to deliver nutrients and oxygen to the working tissues during sustained exercise and to remove metabolic waste products that would cause fatigue.1–3 The ability of the body to utilize oxygen and remove waste products during exercise is dependent on the efficiency of the cardiorespiratory system.1–3 The CRS is like other systems; the better you train it, the more efficient it becomes at providing the tissues with oxygen and removing waste products during exercise and activity.

Cardiac Output, Stroke Volume, Heart Rate, and Oxygen Consumption

One of the most important factors in cardiorespiratory endurance is the efficiency with which the CRS can supply oxygenated blood to the working tissues. Two major determinants for cardiorespiratory endurance are stroke volume and heart rate,3,4 referred to as cardiac output. Cardiac output can be defined as the amount of the blood ejected by the heart each minute.3,4

Cardiac output = stroke volume + heart rate

Stroke volume (SV) is the amount of blood ejected by the ...

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