Friday, May 11, 2007

Submaximal Estimation of Vo2 Max

Submaximal Estimation of Vo2 Max.
From Thor Nielsen Lecture Notes 1999.
The Oxygen Carrying Capacity of Blood Hemoglobin
In men there is approximately 15-16g of hemoglobin in each 100ml of blood. The value is about 5- 10% less for women and averages about 14g per 100ml of blood. The reason for the difference may be the stimulating effect on red blood cell production of the ‘male’ hormone testosterone. Each gram of hemoglobin can combine loosely with 1.34ml of oxygen. Thus if the hemoglobin content of the blood is known, its oxygen carrying capacity can easily be calculated as follows:

Blood O2 capacity = Hemoglobin x O2 capacity of hemoglobin
(ml per 100ml blood) (g per 100ml blood) x (1.34ml per gram)

On average, approximately 20ml of oxygen would be carried with the hemoglobin in each 100ml of whole blood when its hemoglobin is fully saturated with oxygen.

12g x 1.34ml = 16.08 ml of O2/100ml blood
13g x 1.34ml = 17.42 ml of O2/100ml blood
14g x 1.34ml = 18.76 ml of O2/100ml blood
15g x 1.34ml = 20.10 ml of O2/100ml blood
16g x 1.34ml = 21.44 ml of O2/100ml blood
17g x 1.34ml = 22.78 ml of O2/100ml blood

Sub Maximal Test to Estimate Stroke Volume and VO2 Max

Concept II Model C/D Rowing Ergometer
Heart rate Monitor Polar S210/S610/S810 or other HRM that records HR

Warm up: 5min - Max Heart rate 135.
Rest after warm up: 3min – No activity
Test Time: 5min at prescribed load. Must maintain accurate watts. No large changes

Recommended Load on Concept II:
Women -160 Watts
Junior Men/Lightweight Men -210 Watts
Senior Men -260 Watts

Data Collected:
Average heart rate for last 90 seconds of 5 minute test.
Collect heart rate data every 10s for last 90s then average this data

The following table shows the oxygen consumption required to maintain work at the different loads. The corresponding cardiac output is based on an expected haemoglobin content of 15gr./ml blood.

Work Load VO2 l/min Cardiac Output l/min Card Output ml/min
110 2.25 16.25 16250
160 2.75 18.75 18750
210 3.45 23.25 23250
260 4.15 25.75 25750
310 5.05 30.25 30250

The calculation used to estimate stroke volume
Cardiac output (ml) / Heart rate = Estimated Stroke Volume
(From Table) (last 90s) (ESV)

Use of stroke volume to estimate Max VO2:
Max heart rate x Estimated stroke volume =Blood transport l/min.
(Max HR) (ESV)

It is expected that 15gr. Haemoglobin per ml of blood gives 200ml O2 per litre of blood.
Blood transport l/min x 200ml = Oxygen transport in L/min

This is then multiplied by an utilisation factor:
Junior – 80%,
Senior B International (U23) – 85%,
Senior A International – 90%.

200 Max HR x 150 ESV = 30 l/min blood transport
30 l x 0.2 = 6 l/min max O2 transport
Utilisation: Senior A International – 90%
Estimated VO2 Max = 6.00 x 0.90
= 5.4l/min

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