Physiology, Health & Exercise

1. Physiology, Health & Exercise Lesson 11 The Principles of Exercise Testing

2. Principles of exercise testing Include: • Use of maximal and sub-maximal tests • VO2 max • Exercise stress testing • Cardiac patient rehabilitation

3. Why measure physiological fitness? • To monitor effectiveness of a training programme for an athlete • To monitor recovery from MI

4. 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 maxthe greater the aerobic fitness of the individual

5. 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.

6. VO2 max

7. 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

8. 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

9. 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

10. Sub-maximal testing • Graph here pulse v vo2 max

11. 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

12. Typical VO2 max values • top endurance athletes usually have a very high VO2 max around 70ml/kg/min • average person has a VO2maxaround 35 ml/kg/min • a low VO2max < 25ml/kg/min usually means you would be poor at endurance events

13. 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 VO2max • Fitness test

14. Examples of Sub-maximal tests • Examples of sub-maximal tests are: • Step tests • 20-metre shuttle run • shuttle walking test

15. 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

16. 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

17. 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

18. 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

19. 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 VO2max

20. Shuttle walking test • similar to shuttle run, however subject walks • more suitable for less fit individuals

21. 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

22. 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

23. 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

24. Question Homework • Describe the effects of exercise training on the cardiovascular system 8 marks • Discuss the principles of exercise testing 7 marks • Hand in- 08/02/10