to Increase Cardiovascular Fitness

CHAPTER THREE Exercise to Increase Cardiovascular Fitness

This chapter gives an overview of cardiovascular fitness. Training adaptations seen following a successful cardiovascular training programme are outlined, along with the principles of assessment and prescription and example exercises for increasing cardiovascular fitness. These principles are related to current guidelines for cardiovascular training.

DEFINITION

Cardiovascular fitness, aerobic capacity and endurance are all terms used to describe the body’s ability to sustain exercise over a period of time. Exercise designed to increase cardiovascular fitness is often termed ‘aerobic exercise’ as sustained exercise uses the aerobic pathways of oxidative phosphorylation for energy supply and training adaptations result in a more efficient aerobic energy pathway. Such exercise generally targets large muscle groups and aims to overload the cardiovascular system, thus increasing heart rate and respiratory rate during exercise.

FACTORS DETERMINING CARDIOVASCULAR FITNESS

An individual’s cardiovascular fitness is dependent on a number of factors, which combine to form the oxygen uptake chain. Oxygen must be delivered to the lungs by adequate ventilation, and then must pass into the blood at the alveolar level. The circulatory system carries the oxygenated blood to the working muscle where the oxygen is taken up by the mitochondria (Table 3.1).

Table 3.1 Factors determining cardiovascular fitness

Determining factor	Influencing factors	Effect
Ability of the respiratorysystem to supply oxygen to blood	Respiratory pathology	Limits gas exchange and ventilation
	Neuromuscular pathology	Limits muscles of ventilation
	Altitude	Fraction of inspired O2 available
Ability of the blood to carry the oxygen	Anaemia	Reduced carrying capacity
	Circulatory disorders	Restricts delivery of oxygenated blood to working muscle
	Aerobic training – volume of circulating plasma	Oxygen-carrying capacity
Ability of the heart to pump the blood to the working muscle	Cardiac pathology	Reduced cardiac output
	Aerobic training – left ventricular hypertrophy	Increased cardiac output
Ability of the muscles to uptake and utilize the oxygen from the blood	Aerobic training – increased capilliarization of trained muscle	Increased oxygen delivery to muscle
	Aerobic training – number and size of mitochondria	Increased ability to uptake and utilize oxygen
	Oxyhaemoglobin dissociation curve	Ease of transfer of oxygen from blood to working muscle

TRAINING ADAPTATIONS

The physiological training adaptations that take place following aerobic training can be divided into local adaptations, seen in the muscles used during the training exercises, and systemic adaptations. These physiological adaptations are seen approximately 6 weeks into a training programme. Performance in exercise tests may improve before physiological adaptations are detectable, and this may be due to other factors such as improved skill in task performance and increased confidence during exercise.

Local training adaptations

Local adaptations occur in trained skeletal muscles which enable them to uptake and utilize oxygen more efficiently. These adaptations are as follows.

Capillaries

An increase in the number and size of capillaries within the trained muscle, providing a greater surface area for delivery of oxygen and removal of waste products by the blood.

Mitochondria

An increase in both the size and number of mitochondria in all skeletal muscle fibre types within the trained muscle. This increase in mitochondrial material also results in a doubling of the oxidative enzymes, thus increasing the capacity to produce adenosine triphosphate (ATP) using the aerobic pathways.

Lipolysis

An increase in lipolysis, resulting in a greater use of fatty acid for energy supply.

Muscle fibre type

There is some evidence to suggest that aerobic training leads to conversion from type 2 to type 1 muscle fibres.

Hypertrophy

Selective hypertrophy of the type 1 fibres occurs, resulting in a greater surface area of slow-twitch fibres.

PRINCIPLES OF CARDIOVASCULAR EXERCISE DESIGN

When designing an exercise programme to increase cardiovascular fitness the following principles should be considered.

Energy source

The exercise duration should be long enough for the aerobic pathways to become the main source of energy production, which occurs after approximately 5 minutes of exercise.

Rhythmical

Cardiovascular exercises use large muscle groups and are often rhythmical in nature.

Specificity

Although cardiovascular training has systemic effects that contribute to an overall increase in exercise capacity, it is also muscle- and task-specific. Therefore the exercises should be designed with individual patient goals in mind.

Range of exercises

For the greatest training effect both upper and lower limb activities should be included in the programme of exercise. If using a variety of exercises it is desirable to alternate the emphasis on particular muscle groups when sequencing the exercises to avoid local muscle fatigue; for example adding a ‘throwing and catching’ exercise in between ‘sit to stand’ and ‘stair climbing’ allows the quadriceps to recover.

The exercise programme may be one continuous activity, such as jogging, or comprise a combination of exercises such as circuit training.

Intensity level

When designing a circuit, care should be taken to ensure that the heart rate is maintained within the required parameters for training during all activities, although there may be a combination of high- and lower-intensity activity throughout the circuit. Using a range of exercises at different training intensities allows recovery periods in between bursts of higher-intensity activity. A baseline level of activity should be maintained to prevent rapid decreases in heart rate (see Cool down).

Safety

Before prescribing a cardiovascular exercise programme the person’s cardiovascular system should be assessed and safe limits of exercise clearly set. Healthy individuals can exercise within the normal guidelines, but individuals with respiratory, cardiac or circulatory disorders could become severely compromised by the stress placed on their cardiovascular system, and they should be carefully assessed and specific levels of activity applied. It is good practice to monitor the heart rate during the exercises whilst under supervision of the physiotherapist to check for any unexpected response to exercise, before instructing the person to carry out the exercises in an unsupervised environment.

Activities that include a jumping, running or bouncing component are classed as high impact and will be of higher intensity. There is an increased risk of injury with high-impact exercise and it may not be appropriate for some people, in which case the activity should be modified to remove the jump component.

WARM UP AND COOL DOWN

A warm up and cool down should always be incorporated into a cardiovascular training routine.

Warm up

A warm up may comprise exercises that are included in the exercise programme itself, but should start at a low intensity and gradually build up to the required training intensity over a period of 10 minutes. This is to allow a gradual redistribution of blood to the exercising muscles, in particular the cardiac muscle.

Cool down

A period of around 10 minutes, during which the intensity of exercise is gradually reduced, is important immediately following exercise. This cool-down period maintains muscle contraction of the exercised muscles, which aids the redistribution of blood after exercise and prevents blood pooling in the peripheral muscles, which can lead to fainting.

Therefore the main purpose of the warm up and cool down is the gradual change in heart rate and the redistribution of blood. Warm up is often seen as essential for injury prevention, and there is some evidence in the literature to suggest that warm muscles are less vulnerable to injury as they have increased extensibility.

Stretching is often incorporated into the warm up and cool down; however stretching before exercise can reduce performance and has little effect on injury (Stone 2006).

Tags: The Physiotherapists Pocket Guide to Exercise Assessment

Nov 7, 2016 | Posted by admin in MANUAL THERAPIST | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access