Lecture 12 Exercise Physiology

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Fitness testing - A brief overview
Lecture 12 Exercise Physiology For modules in
Cardiac and Pulmonary Rehab Professor Bruce
Lynn MSc School of Human Health and Performance
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• Problems with max tests in average/less fit
  subjects
• May not be accustomed to exercise at severe
  levels, so may not reach maximum
• On a bike, need strong quads, so lightly built
  subjects, possibly most female subjects, will
  lack strength to reach VO2max
• Can use treadmill, but significant minority find
  treadmill disorienting or have balance problems
• For population surveys, need quicker, less
  stressful, test
• For at risk groups, older subjects, maximal
  testing is considered too dangerous

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Submaximal exercise tests Most follow this
pattern Subjects does standardised work
schedule Heart rate is measured Work capacity at
age-predicted heart rate max is calculated Oxygen
consumption at work rate calculated for HRmax is
estimated from average relation between VO2 and
work rate for the test Can use a single point
(e.g. Astrand-Rhyming nomogram), or measure
multiple points (e.g. YMCA test) or could use a
short ramp test
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Drawbacks of submaximal tests Assume reliable
HR-VO2 relation across subjects (1 point tests)
or linearity of HR relation for multi-point
tests Depend on estimating age-related
HRmax.(error /- 10) Assume same VO2-work
relation in all subjects, i.e. constant
efficiency Are subject to error from fluctuations
in HR due to time of day, eating patterns,
uncontrolled stressors. McArdle estimates a
typical submax test can only give VO2max
estimates to within /- 16
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Single measurement of steady state heart rate Can
use step or bicycle ergometer Nomogram is for age
25 years Need to adjust for older and younger
(for which standard table available) Can use
underlying equations as in calculator at -
http//www.archway.ac.uk/Activities/Departments/SH
HP/Exercise_Health/Step_Test.html
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Field Tests

• 12 min run
• VO2 3.126 (meters in 12 min) - 11.3
• 1.5 mile run
• VO2 3.5 483/(time in minutes)
• Rockport Walking Test (1 mile walk)
• VO2 132.853 - 0.1692 (BW in kg) - 0.3877 (age
  in y) 6.315 (gender) - 3.2649 (time in min) -
  0.1565 (HR)
• 0 for female 1 for male HR at end of walk

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Non-exercise methods 1. Use resting heart rate
variability.
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Heart rate variability during exercise Best by
beat variability falls during exercise. This is
due to reduction in vagal (parasympathetic) drive
to the heart. Part of the way heart rate is
increased (NB other factors are increased
sympathetic drive and circulating adrenaline)
Instantaneous heart rate, min-1
Resting
Moderate-hard exercise
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Non-exercise methods 1. Use resting heart rate
variability.
POLAR have a watch that does this. But relation
of HRV to fitness not close. Graph shows our
data for n71. Young male participants. RMSSD is
measure of beat by beat variation in heart
rate. r 0.36 not good enough for use on its
own to predict fitness.
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Non-exercise methods 2. Use just age, gender,
level of physical activity, perceived functional
ablility (latter two from simple questionnaires).
Claimed can estimate fitness to within /- 3.4
ml/min.kg (SEE, standard error of estimate, so 5
confidence limit about 7 ml/min.kg). This appears
better than any of the real tests, so some
doubt that comparisons are being made in a fair
way. George, J.D., et al. Nonexercise VO2max
estimation for physically active college students
Med. Sci. Sports Exerc., 29415, 1997.
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Monitoring change in fitness Submax exercise
tests are much more reliable on repeat testing in
the same individual. So for following the effect
of an exercise for health individual programme,
they are fine. But in this situation may be
better to forget VO2max altogether. Simply
follow trend in final heart rate for a standard
exercise, e.g. short step test or timed walk test.
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Summary Fitness levels vary markedly between
individuals and are highly predictive of future
health. Need simple methods to monitor fitness in
individuals and in populations Various sub-max
tests are suitable for this purpose. However,
because of inherent non-linearities in the
underlying physiology, will have low
accuracy. For reliable VO2max estimates in a
performance context or clinically, need a maximum
test.
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Much information in standard exercise physiology
texts, e.g. McArdle, Exercise Physiology
Astrand, Textbook of Work Physiology Powers and
Howley, Exercise Physiology. Lot of information
in ACSM Guidelines for exercise testing and
prescription, 6th edn, 2000. Detail on
underlying physiology and pathophysiology, see
Wasserman et al, Principles of Exercise Testing
and Interpretation, 2005. Lippincott WW. Nice
PPT about exercise testing on web academic.wsc.ed
u/faculty/taeveto1/ped470/lecture/ppt/aerobic.ppt
Web sites Brian Mackenzies Sports Coach site
has a lot of interesting stuff on testing
http//www.brianmac.demon.co.uk/