Chapter 7 Aerobic Exercise

Training thresholds

Training stimulus thresholds are variable initial level of fitness, the greater the intensity of exercise needed to elicit a significant change

Warm-up period

! An increase in muscle temperature. The higher temperature increases the efficiency of muscular contraction by reducing muscle viscosity and increasing the rate of nerve conduction. ! An increased need for oxygen to meet the energy demands for the muscle. Extraction from hemoglobin is greater at higher muscle temperatures, facilitating the oxidative processes at work. ! Dilatation of the previously constricted capillaries with increases in the circulation, augmenting oxygen delivery to the active muscles and minimizing the oxygen deficit and the formation of lactic acid

Functional Implications energy systems

! Bursts of intense activity lasting only seconds develop muscle strength and stronger tendons and ligaments. ATP is supplied by the phosphagen system. ! Intense activity lasting 1 to 2 minutes repeated after 4 minutes of rest or mild exercise enhances anaerobic power. ATP is supplied by the phosphagen and anaerobic glycolytic system. ! Activity with large muscles, which is less than maximum intensity for 3 to 5 minutes repeated after rest or mild exercise of similar duration, may develop aerobic power and endurance capabilities. ATP is supplied by the phosphagen, anaerobic glycolytic, and aerobic systems. ! Activity of submaximum intensity lasting 20 to 30 minutes or more taxes a high percentage of the aerobic system and develops endurance.

Principles of Stress Testing

! Changing the workload by increasing the speed and/or grade of the treadmill or the resistance on the bicycle ergometer ! An initial workload that is low in terms of the individual's anticipated aerobic threshold ! Maintaining each workload for 1 minute or longer ! Terminating the test at the onset of symptoms or a definable abnormality of the ECG ! When available, measuring the individual's VO2 max

Stress Testing

! Changing the workload by increasing the speed and/or grade of the treadmill or the resistance on the bicycle ergometer ! An initial workload that is low in terms of the individual's anticipated aerobic threshold ! Maintaining each workload for 1 minute or longer ! Terminating the test at the onset of symptoms or a definable abnormality of the ECG ! When available, measuring the individual's VO2 max

Preparation of Stress Testing

! Have had a physical examination ! Be monitored by ECG and closely observed at rest, during exercise, and during recovery ! Sign a consent form

Purpose of Stress Testing

! Helps establish a diagnosis of overt or latent heart disease. ! Evaluates cardiovascular functional capacity as a means of clearing individuals for strenuous work or exercise programs. ! Determines the physical work capacity in kilogram-meters per minute (kg-m/min) or the functional capacity in METs. ! Evaluates responses to exercise training and/or preventive program

Purpose of Stress Testing

! Helps establish a diagnosis of overt or latent heart disease. ! Evaluates cardiovascular functional capacity as a means of clearing individuals for strenuous work or exercise programs. ! Determines the physical work capacity in kilogram-meters per minute (kg-m/min) or the functional capacity in METs. ! Evaluates responses to exercise training and/or preventive programs.

Common aerobic impairments

! Increased susceptibility to thromboembolic episodes, pneumonia, atelectasis, and the likelihood of fractures ! Tachycardia, dizziness, and orthostatic hypotension when moving from sitting to standing ! A decrease in general muscle strength, shortnesss of breath ! Increased HR and blood pressure responses (rate-pressure product) to various activities

Termination of Stress Testing

! Onset and/or progressive angina ! A significant drop ( !10 mm Hg) in systolic pressure in response to an increasing workload ! Lightheadedness, confusion, pallor, cyanosis, nausea, peripheral circulatory insufficiency, shortness of breath, wheezing, or leg cramps ! Excessive rise in blood pressure

Cool Down period

! Prevent pooling of the blood in the extremities by continuing to use the muscles to maintain venous return ! Prevent fainting by increasing the return of blood to the heart and brain as cardiac output and venous return decreases ! Enhance the recovery period with the oxidation of metabolic waste and replacement of the energy store ! Prevent myocardial ischemia, arrhythmias, or other cardiovascular complications

Common aerobic impairments goals w conditioing

! Prevent thromboembolic episodes, pneumonia, atelectasis, and fractures ! Decrease the magnitude of the orthostatic hypotensive response ! Improve ability to climb stairs safely and without shortness of breath ! Develop tolerance for walking longer measured distances and completing activities without fatigue or symptoms ! Decrease HR and blood pressure

Steady State

! Steady state is reached within 3 to 4 minutes after exercise has started if the load or resistance is kept constant. ! In the steady-state period, VO2 remains at a constant (steady) value.

Duration of CV condiitoning

A 20- to 30-minute session is generally optimal at 70% HRmax . When the intensity is below the HR threshold, a 45-minute continuous exercise period may provide the appropriate overload.

Overload Principle

A conditioning response occurs generally at 60% to 90% maximum heart rate (HRmax; 50% to 85% VO2 max) depending on the individual and the initial level of fitness The exercise HR is determined in one of two ways: (1) as a percentage of the HRmax (the percentage used is dependent on the level of fitness of the individual) or (2) using the HR reserve (HRR; Karvonen's formula). Karvonen's formula is based on the HRR, which is the difference between the resting HR (HRrest ) and the HRmax

Aerobic Exercise Training (Cardiorespiratory Endurance)

Aerobic exercise training, or cardiorespiratory endurance training, is an improvement of the energy utilization of the muscle by means of an exercise program The improvement of the muscle's ability to use energy is a direct result of increased levels of oxidative enzymes in the muscles, increased mitochondrial density and size, and an increased muscle fiber rcapillary supply.

Reversibility Principle

Detraining occurs rapidly when a person stops exercising. After only 2 weeks of detraining, significant reductions in work capacity can be measured, and improvements can be lost within several months The frequency or duration of physical activity required to maintain a certain level of aerobic fitness is less than that required to improve it.

Karoven Formula

Exercise HR = HRrest+ 60%-70% (HRmax - HRrest)

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 Fitness levels can be described on a continuum from poor to superior based on energy expenditure during a bout of physical work.

VO2 Max

Maximum oxygen consumption (VO2 max) is a measure of he body's capacity to use oxygen It is usually expressed relative to body weight, as milliliters of oxygen per kilogram of body weight per minute (mL/kg per minute).

Phosphagen system

Phosphagen, or ATP-PC, System The adenosine triphosphate-phosphocreatine (ATP-PC) system has the following characteristics: ! PC and ATP are stored in the muscle cell. ! PC is the chemical fuel source. ! No oxygen is required (anaerobic). ! When muscle is rested, the supply of ATP-PC is replenished. ! The maximum capacity of the system is small (0.7 mol ATP). ! The maximum power of the system is great (3.7 mol ATP/min). ! The system provides energy for short, quick bursts of activity. ! It is the major source of energy during the first 30 seconds of intense exercise

Recruitment of Motor units

Slow-twitch fibers (type I) are characterized by a slow contractile response, are rich in myoglobin and mitochondria, have a high oxidative capacity and a low anaerobic capacity, and are recruited for activities demanding endurance. These fibers are supplied by small neurons with a low threshold of activation and are used preferentially in low-intensity exercise. Fast-twitch fibers (type IIB) are characterized by a fast contractile response, have a low myoglobin content and few mitochondria, have a high glycolytic capacity, and are recruited for activities requiring power. Fast-twitch fibers (type IIA) have characteristics of both type I and type IIB fibers and are recruited for both anaerobic and aerobic activities.

Aerobic System

The aerobic system has the following characteristics: ! Glycogen, fats, and proteins are fuel sources and are utilized relative to their availability and the intensity of the exercise. ! Oxygen is required (aerobic). ! ATP is resynthesized in the mitochondria of the muscle cell The ability to metabolize oxygen and other substrates is related to the number and concentration of the mitochondria and cells. ! The maximum capacity of the system is great (90.0 mol ATP). ! The maximum power of the system is small (1.0 mol ATP/min). ! The system predominates over the other energy systems after the second minute of exercise.

Anaerobic Glycolytic System

The anaerobic glycolytic system has the following characteristics: ! Glycogen (glucose) is the fuel source (glycolysis). ! No oxygen is required (anaerobic). ! ATP is resynthesized in the muscle cell. ! Lactic acid is produced (by-product of anaerobic glycolysis). ! The maximum capacity of the system is intermediate (1.2 mol ATP). ! The maximum power of the system is intermediate (1.6 mol ATP/min). ! The systems provide energy for activity of moderate intensity and short duration. ! It is the major source of energy from the 30th to 90th second of exercise.

Adaptation

The cardiovascular system and the muscles used adapt to the training stimulus over time. Performance improves in that the same amount of work can be performed after training but at a lower physiological cost.

Outpatient Cardiac Rehabilitation: Early Exercise Program phase 2

The early outpatient exercise program is initiated within 1 to 3 weeks of discharge from the hospital and lasts up to 36 sessions. Purpose = ! Increase the person's exercise capacity in a safe, progressive manner so adaptive cardiovascular and muscular changes occur. The early part of the program might be considered by some as "low-level" exercise training. ! Enhance cardiac functions and reduce the cardiac cost of work. This may help eliminate or delay symptoms such as angina and ST-segment changes in the patient with coronary heart disease. ! Produce favorable metabolic changes. ! Determine the effect of medications on increasing levels of activity. ! Relieve anxiety and depression. ! Progress the patient to an independent exercise program.

Type of CV conditionng

The important factor is that the exercise involves large muscle groups that are activated in a rhythmic , aerobic nature. Training benefits are optimized when programs are planned to meet the individual needs and capacities of the participants

Maintenance Program phase 3

The purpose of the program is to continue to improve or maintain fitness levels achieved during early outpatient cardiac rehabilitation and to continue secondary prevention activities to assist with behavior change and risk factor modification.

MET

defined as the oxygen consumed (milliliters) per kilogram of body weight per minute (mL/kg). It is equal to approximately 3.5 mL/kg per minute ! Light activity is 2.0 to 2.9 METs or 3.5 to 10.15 mL/kg per minute. ! Moderate activity is 3.0 to 5.9 METs or 10.5 to 10.65 mL/kg per minute. ! Vigorous activity is 6 to 8.8 METs or 21 to 30.8 mL/kg per minute.

Impatient Cardiac Rehab Phase 1

generally lasts 3 to 5 days. Initiate risk factor education and address future modification of certain behaviors, such as eating habits and smoking. ! Initiate self-care activities and progress from sitting to standing to minimize deconditioning (1 to 3 days post event). ! Provide an orthostatic challenge to the cardiovascular system (3 to 5 days post event). This is usually accomplished by supervised ambulation. Prepare patients and family for continued rehabilitation and for life at home after a cardiac event

Endurance

is the ability to work for prolonged periods of time and the ability to resist fatigue. Muscular endurance refers to the ability of an isolated muscle group to perform repeated contractions over a period of time, cardiovascular endurance refers to the ability to perform large muscle dynamic exercise, such as walking, swimming, and/or biking for long periods of time.

Myocardial oxygen consumption

measure of the oxygen consumed by the myocardial muscle The ability to supply the myocardium with oxygen is dependent on the arterial oxygen content (blood substrate), hemoglobin oxygen dissociation and coronary blood flow

Deconditioning

occurs with prolonged bed rest, and its effects are frequently seen in the patient who has had an extended, acute illness or long-term chronic condition deceased workload capacity decreased circulating blood volume

3 Energy Systems

phosphagen, glycolysis, oxidative