chapter 6 impaired aerobic capacity/endurance

Copyright 2005 Lippincott Williams & Wilkins

Chapter 6Impaired Aerobic

Capacity/Endurance


Physiology of Aerobic Capacity and Endurance

Physical Activity Exercise Physical Fitness

Cardiorespiratory Endurance

The ability of the whole body to sustain prolonged exercise.


Energy Sources Used During Aerobic Exercise

Fat, Carbohydrates, Protein

ATP ATP ATP


Metabolic Pathways


Fuel Source Selection During Exercise

CHO is the preferred fuel source for ATP to supply

the body with energy during exercise.


Normal and Abnormal Response to Acute Aerobic Exercise

Heart Rate – Linear relationship between HR and intensity of exercise (factors – age, fitness level, type of activity, disease, medications, bl volume, environment).

Stroke Volume – Workload and SV increase linearly until 50% aerobic capacity (factors – body composition and exercise intensity).


Cardiac Output

• Cardiac output and workload increase linearly b/c of increases in HR and SV (factors – age, posture, body size, disease, physical conditioning).

• Arterial/venous oxygen difference – As exercise increases a-VO2 diff increases linearly.

• Blood flow – at rest 15–20% muscle.During exercise 80–85% muscle.


• Blood pressure – Systolic BP linearly with work load. Diastolic BP changes very little.

• Pulmonary ventilation – During exercise, breathing increases to facilitate amount of air exchanged per minute. Tidal volume and respiratory rate increase in proportion to exercise.


Physiologic and Psychological Adaptations to Cardiorespiratory Endurance Training

Increased• Heart wt, vol• Left ventricle size• SV, cardiac output• Hemoglobin• Peripheral capillary

formation• Respiratory rate• PV during max exercise• Vo2, Vo2 different during

maximal exercise

Decreased• Resting and submax HRs• Time required to return to

resting levels• Systolic/diastolic pressure• Resting and submaximal

respiratory rates• Body fat


Psychologic Benefits of Training

ImprovedMoodsDepressionAnxietyPsychological well-beingPerceived quality of life


Causes of Impaired Aerobic Capacity/Rehabilitation Indications

Heart MuscleCoronary artery

diseasePericarditisCongestive heart

failureAneurysms

Heart ValvesRheumatic feverEndocarditisMitral valve prolapseCongenital deformities


Nervous SystemArrythmiase.g., tachycardia,

bradycardia

Peripheral Vascular Disease

Arterial disorders, venous disorders, lymphatic disorders

e.g., atherosclerosis, embolism, Buerger’s disease, Raynaud’s, deep vein thrombosis, lymphedema, venous stasis


Examination/Evaluation of Aerobic Capacity

Examination and evaluation of CV and respiratory systems should be included in exam of all clients

Tests IdentifyPresence of diseaseEstablishing a

baseline aerobic capacity

Measuring change in aerobic capacity


Patient/Client History

General demographic informationSocial/health habitsGeneral health status (physical, role, social

functioning, etc.)Clinical tests (blood cholesterol)Medications


Systems Review

Examination of other major body systems

Skin integrityMuscle strengthJoint ROMBalanceGait functionAbility to make needs

known

CommunicationAffectCognitionLanguageLearning style


Screening Examination

Pain in chest, neck, jaws, or areas of ischemia

Shortness of breath at rest or with mild exertion

Dizziness or syncopeOrthopneaAnkle edema

Palpitations or tachycardia

Intermittent claudication

Known heart murmurUnusual fatigue or

shortness of breath with usual activities


Tests and Measures

Maximal Graded Exercise Tests Graded or variable workload over 8-12 min.

Commonly done in conjunction with ECG.

Submaximal Graded Exercise Tests Estimates VO2max. Includes bicycle ergometer

tests (Astrand-Ryhming, YMCA protocol), treadmill tests, step tests, field tests.


Anthropometric Characteristics

Hydrostatic – gold standard (requires expensive specialized equipment and patient tolerance)

BMI (body mass index)Bioelectric impedanceNear-infrared interactanceSkinfold measurements


Circulation

Blood pressureHeart rate, rhythm,

and patternRespiratory rate,

rhythm, and pattern


Therapeutic Exercise Intervention

Objective of exercise prescription is to assist in the adoption of regular physical activity as a lifestyle habit.

Consider – behavioral characteristics, personal goals, exercise preferences of the individual.


Mode of Intervention

WalkingJoggingCross-country skiingBicycling

Rope jumpingRowingSwimming (or water

aerobics)Aerobic dance


Dosage – Training Type

Continuous – (e.g., 30 minutes using 1 or 2 exercises)

Interval Training – Multiple bouts of higher intensity w/ short periods of rest/light activity (e.g., 2 minutes)

Circuit Training - Individual rotates through series of exercise stations.


Dosage – Training Sequence

1. Initial warm up (5–10 minutes) of large muscle groups (walking, cycling, etc.)

2. Stretching exercises3. More vigorous

cardiovascular exercises as prescribed

4. Cool down with stretching

1&4

2&4

3


Dosage – Frequency

Determined considering patient’s goalsOptimal frequency – 3–5 times per week


Dosage – Intensity

Based on overload principle and within the patient’s functional limitations

Select a training range to allow for flexibility (e.g., 60–70% of HR max)

60–80% has been the general recommendation


Dosage – Duration

Depends on goals, frequency, intensity & conditioning level of patient

Optimal duration is 20–30 minutes per session

If unable, several 10-minute sessions can be performed until tolerance increases


Precautions and Contraindications

Refer to systems review and physiologic causes of impairment

Consider any injury or disease affecting systems (e.g., patients with DJD could participate in non-weight-bearing exercises)


Supervision During Exercise

Initial screening and medical evaluation are important to determine if the individual requires supervision.


Patient-Related Instruction/Education

Patient education (PE) should include “why” & “how” of warm up, training, and cool down phases.

PE on negative signs and symptoms necessitating cease of activity.

PE should include maintenance program upon discharge and importance relating to long-term health maintenance.


Life Span Guidelines

Children exercising in hot environments should do so at lower intensity.

Age 6 up to & including adults – moderate intensity, 30 minutes, 5–7 days/wk.

Elderly individuals – 30 minutes, 5–7 days/wk with emphasis on minimizing impact on joints (e.g., water exercising, cycling).


Summary Aerobic capacity or

VO2max is the highest rate of oxygen the body can consume during maximal exercise.

CHOs are the preferred energy source for the body during exercise.

During acute exercise, HR, SV, Q, a-vO2 diff, BP, and RR increase proportionally to the exercise workload.

Benefits of CV endurance training include +ve changes in CV & resp. systems that provide protection from disease & improved psych. well-being and quality of life.

Impaired aerobic capacity can occur – result of primary CV & pulm. disease, diseases of other systems that limit mobility, prolonged bed rest, aging, and sedentary lifestyle.


Summary (cont.) Areas of PT history requiring

attention are: risk factors for CV disease, social/health habits such as smoking and physical activity, functional ability, and medication history.

Tests and measures include: graded exercise tests, body composition, tests/measures of circulation (e.g., blood pressure).

Exercise prescription should be based on the results of an appropriate exercise test b/f the initiation of a CV program.

CV endurance training can be performed using a variety of exercise modes and training techniques.

Exercise prescription should be based on the individual’s needs and interests, and comorbidities that affect activity performance should be considered.


Summary (cont.) CV endurance training is

part of a well-balanced exercise program including muscle strengthening, endurance, and flexibility exercises.

Clinician should be able to identify signs and symptoms, intolerance, and contraindications for graded testing.

Supervision requirements are based on patient’s history, risk factors, and abilities.

Educating the patient regarding the specifics of the program(s) will increase the likelihood of patient compliance and adoption of CV exercise as a lifelong habit.

chapter 6 impaired aerobic capacity/endurance

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