biodex 950-214, Installation & Operation Manual

Page: 25 / 48

BIODEX ERGOMETERS SUPPORT METs AND AID EXERCISE PRESCRIPTION FOR
BOTH CARDIOPULMONARY AND MEDICAL FITNESS
A cardiac stress test typically reports the max MET level achieved by the patient and/or the
MET level achieved at the point the test turned positive (often demonstrating schemic changes
in the heart muscle and/or inappropriate arrhythmias). Cardiologists often ask therapists to
keep a patient below a certain MET level based on this information from the cardiac stress test.
The Cardiologist will report, for example, “schemic changes at 10 METs/Heart Rate 128.
Exercise at or below 9 METs”.
Different types of cardiovascular exercise machines require the user to work at different work
loads (WATTs) to ensure a consistent elevation of an individual’s metabolic rate and the corre-
sponding appropriate heart rate. Cranking an upper body cycle at 100 WATTs will, for example,
have a very different effect on one’s metabolic rate and heart rate when compared to stepping a
lower body cycle at 100 WATTs. It is up to the clinician to set the appropriate workloads on each
ergometer, or speed and elevation on the treadmill, to achieve the appropriate MET level.
THE RELATIONSHIP OF CALORIES BURNED TO OXYGEN CONSUMPTION AND METs
For every liter of oxygen consumed by the body during exercise, the body burns approximately
5 calories. The example below shows a 150 lb (68 kg) individual exercising at a level requiring
an oxygen consumption of 1 liter (1,000 ml) of oxygen each min., which would require that they
burn 5 calories each min. to supply the appropriate amount of energy for the exercise. This same
individual would be burning 14.6 milliliters of oxygen for each kilogram of body weight per
min. (1,000 ml of oxygen / 68 kg of body weight). Since one MET = (oxygen consumption in
ml/kg/min.) / (3.5), this individual would be exercising at 4 METs. They would need to elevate
their resting metabolism approximately 4 times to achieve this sustain this rate of exercise.
NOTE: In a study designed to examine the test-retest reliability and concurrent criterion validity of
VO
2max
on the BioStep in community-dwelling older adults, results provided preliminary evidence of
reliable and valid estimates of oxygen consumption by the BioStep when compared with the criterion
standard of direct VO
2max
measurement in the sample.
Reference: Mendelsohn, M.E., Connelly, D.M., Overend, J.J., Petrella, R.J.:Reliability and validity of
responses to submaximal all-extremity semi-recumbent exercise in older adults. Journal of Aging and
Physical Activity, 2007, 15, 184-194.
CONTENTS
— 25 — ADDITIONAL CONSIDERATIONS
4 METs