# Simple Expression Help..

Discussion in 'Math' started by Art, Jun 21, 2009.

1. ### Art Thread Starter Distinguished Member

Sep 10, 2007
785
61
Hi Guys,
I'm doing a fitness course, and trying to understand an exercise in my text book
involving the prediction of a person's volume of Oxygen uptake.
The test is done in an indirect way, predicting V02 Max based on physiological responses to exercise.

The Procedure goes like this:

1. Record the client's weight in kilograms, and record their resting heart rate.

2. Instruct the client to step up and down to a metronome at a rate of 22 steps per minute.

3. Once 3 minutes has elapsed, measure the client's heart rate for 15 seconds, and multiply
that figure by 4, to give a heart rate in BPM (beats per minute).

4. Use the following equation to obtain a predicted V02 Max in l.min-1:

VO2 max (mL.kg-1.min-1) = 65.81 - (0.1847 hr bpm)

Now note that the -1 in the text book is a small "to the power of" style of printing set to
the top right of the character to it's left, just like the 2 in O2 is a small 2 printed to the bottom right of the O.
Also, there is a dot over the V, which I know means it is to be expressed per unit of time. ie. it is a rate.

Now I'm no math guru, but:
1. Why do we measure the client's weight at all?
2. Why do we take resting and working heart rate and only appear to use one?
3. What does this equation mean in English?

Cheers, Art.

2. ### hgmjr Moderator

Jan 28, 2005
9,030
214
Scan it and post the result. That would help us better envision the equation.

hgmjr

3. ### Art Thread Starter Distinguished Member

Sep 10, 2007
785
61
The example I gave was for women. only hte constants are different for men
Here ya go:

4. ### Mark44 Well-Known Member

Nov 26, 2007
626
1
No idea. It doesn't appear explicitly in the formula you presented.
Again, no idea.
The formula says that the time rate of change of the O2 volume for men (in units of mL/(kg * min) is 111.33 - 0.42 * (resting heart rate beats/min).

The graph of this function is a straight line with negative slope, and with a maximum value of 111.33 mL/(kg*min), which would correspond to someone with a heart rate of 0. Each increment of about 2.2 bpm brings down the value about 1.