I have a theory on how to accurately calculate your calorie expenditure during exercise below lactate threshold.
Anyone who wants to confirm/challenge the following reasoning:
Lets say I tested my VO2max in a laboratory test and found that:
Weight= 70kg
VO2max relative = 50ml/kg/min
VO2max absolute = 3.5L/min
HRmax (at which VO2max was measured) = 200bpm
When I divide the 3.5 litres of oxygen pumped out by my heart every minute by 200bpm, I find that my heart pumps 17.5ml of oxygen for every heart stroke.
Suppose I am exercising below lactate threshold (I am working mostly aerobic), lets say at 150bpm, for one hour. This means my heart is pumping out:
150bpm x 17.5ml/beat = 2.625 litres of oxygen every minute.
This equals 2.625 x 60 = 157.5 litres of oxygen every hour.
1 liter of oxygen produces 4.6-5.0kcal, depending on the proportions of glycogen and fat beeing used as fuel.
For my example, this means that the energy production is somewhere between:
157.5 litres x 4.6kcal/L = 724.5kcal and
157.5 litres x 5.0kcal/L = 787.5kcal.
I know that heart stroke volume increase as HR increase, so that may influence the results to a certain degree (at 150bpm I would be pumping a little less than 17.5ml per stroke).
So... is this reasoning valid?
If it is, all you have to know is your VO2max and you can easily approximate your own energy expenditure from your average HR after a ride, possibly more accurate than your power meter, HR monitor, etc.
_______
Aaberg
Anyone who wants to confirm/challenge the following reasoning:
Lets say I tested my VO2max in a laboratory test and found that:
Weight= 70kg
VO2max relative = 50ml/kg/min
VO2max absolute = 3.5L/min
HRmax (at which VO2max was measured) = 200bpm
When I divide the 3.5 litres of oxygen pumped out by my heart every minute by 200bpm, I find that my heart pumps 17.5ml of oxygen for every heart stroke.
Suppose I am exercising below lactate threshold (I am working mostly aerobic), lets say at 150bpm, for one hour. This means my heart is pumping out:
150bpm x 17.5ml/beat = 2.625 litres of oxygen every minute.
This equals 2.625 x 60 = 157.5 litres of oxygen every hour.
1 liter of oxygen produces 4.6-5.0kcal, depending on the proportions of glycogen and fat beeing used as fuel.
For my example, this means that the energy production is somewhere between:
157.5 litres x 4.6kcal/L = 724.5kcal and
157.5 litres x 5.0kcal/L = 787.5kcal.
I know that heart stroke volume increase as HR increase, so that may influence the results to a certain degree (at 150bpm I would be pumping a little less than 17.5ml per stroke).
So... is this reasoning valid?
If it is, all you have to know is your VO2max and you can easily approximate your own energy expenditure from your average HR after a ride, possibly more accurate than your power meter, HR monitor, etc.
_______
Aaberg