Physiology, Health & Exercise

Lesson 11The Principles of Exercise Testing

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Principles of exercise testing

Include: Use of maximal and sub-maximal tests VO2 max

Exercise stress testing Cardiac patient rehabilitation

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Why measure physiological fitness?

To monitor effectiveness of a training programme for an athlete

To monitor recovery from MI

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How to determine aerobic fitness?

Measure maximum rate at which the body is able to take up and use O2 maximal testing

Called VO2 max

Measured in cm3kg-1min-1 Higher VO2 max the greater the aerobic

fitness of the individual

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VO2 max

Measured by getting the person to run on a treadmill whilst breathing in a measured gas supply

As intensity of exercise increased (increasing speed or gradient of treadmill) more O2 taken in until it reaches a maximum level that does not change even if exercise intensity increased further.

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VO2 max

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VO2 max

Only suitable for evaluating the fitness of competitive athletes

Also requires expensive lab equipment, technical personnel & medical back up

Instead use sub-maximal tests

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Sub-maximal testing

Relies on 2 assumptions: There is a linear correlation between VO2 max,

HR & intensity of exercise That an individuals maximum HR = 220 - their

age

Involves exercise at much lower intensities than maximal testing

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Sub-maximal testing

Pulse rate & O2 uptake are measured at various levels of activity

This data used to draw a graph of pulse rate v O2 uptake

Straight line is drawn and then extrapolated to max HR for that age of person

VO2 max then predicted from graph

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Sub-maximal testing

Graph here pulse v vo2 max

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Sub-maximal testing

2 sources of error with sub-maximal testing: other factors than exercise affect HR e.g.

temperature, anxiety, emotions, previous meal etc

220- age = maximum HR is not necessarily accurate for everyone as it is only an average

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Typical VO2 max values

top endurance athletes usually have a very high VO2 max around 70ml/kg/min

average person has a VO2 max around 35 ml/kg/min

a low VO2 max < 25ml/kg/min usually means you would be poor at endurance events

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Typical VO2 max values

Can enter your own time and distance into BBC Sport Academy Fitness test website to get your own VO2 max. For accuracy you need to have covered a distance greater than 1Km

link to VO2 max

Fitness test

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Examples of Sub-maximal tests

Examples of sub-maximal tests are: Step tests 20-metre shuttle run shuttle walking test

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Step Tests

simplest & most commonly used uses steady-state exercise HR or recovery

HR to evaluate efficiency of cardiovascular response to exercise

several different protocols but all based on same physiological principles

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Step Tests

subject steps up & down from a bench or step at a fixed rate for several minutes (3-5 mins)

height of step & rate of stepping (set by a metronome) vary with different protocols

at end of exercise HR measured for 15-30secs at 1 min intervals for 4 mins after exercise stops recovery rate

fitter subject is, lower HR will be immediately after exercise & faster return to resting level

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Step Tests

can also measure HR continuously during exercise by wearing an HR monitor

can repeat same test after e.g. an exercise programme to indicate an improvement in fitness levels

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20-metre shuttle run

commonly used field test of aerobic fitness

however it is maximal & exhaustive only suitable for moderately fit individuals subjects run between markers positioned

20 metres apart at a pace determined by a pre-recorded tape

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20-metre shuttle run

test starts at a fairly slow pace which increases every minute

subject runs between the 2 markers until they cannot keep up the pace

the number of completed shuttles is recorded and used to predict VO2 max

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Shuttle walking test

similar to shuttle run, however subject walks

more suitable for less fit individuals

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Exercise stress testing

often patients with chronic CHD have normal ECG traces at rest but abnormal ECG traces during exercise

some heart rhythm abnormalities are triggered by exercise

carry out stress tests on a treadmill, when workload increased at an incremental level, while monitoring their ECG

most commonly used protocol is the Bruce Protocol

Bruce protocol

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Cardiac patient rehabilitation

supervised aerobic exercise sessions are included in all cardiac rehabilitation programmes

also offered advice on diet, smoking, alcohol, stress & relaxation

exercise programmes designed to allow patients to improve their physical fitness levels so that they can cope with the demands of everyday life

each patient will have a tailor made programme based on their ECG but all follow same type of profile

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Cardiac patient rehabilitation

initially will start with gentle walking about 1 week after the heart attack or surgery

4-6 weeks later slightly more vigorous activity can be started & muscle strengthening exercises included

shown that this leads to better recovery and survival rates

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Question

Homework Describe the effects of exercise training

on the cardiovascular system 8 marks

Discuss the principles of exercise testing7 marks

Hand in- 08/02/10