Calories Burned Question

It would really depend on your weight, level of fitness, etc. I think for the 30-Day Shred most people enter it into the database as 'circuit training'. Not sure what the other DVD is like.

if you do enter as circuit its 354 calories

if you do enter as circuit its 354 calories

For you based no your info, it will be different for the poster unless they are the same height and weight

The idea is that no two people burn the same amount of calories for an activity. Using the exercise database on MFP is an exercise in wild guessing as this information is entered by users.

Put it this way, if I jog at 5 mph for 45 minutes and a 55 year old woman who is 40 lbs overweight and has only been exercising for 3 months puts the same exercise in, our numbers could be hundreds of calories off.

I see this issue coming up more often and I have a couple of questions.

Based on everything I have learned, within certain limits, caloric expenditure is a function of weight x (absolute) intensity. If you look at the energy prediction equations of the ACSM, there is no distinction made for other factors like age, gender, or fitness level.

In other words, a 20 yr old who weighs 150 lbs running a 10:00 mile should burn essentially the same number of calories per minute as 50 year old female at the same weight (assuming they are both at steady state). That workload might only represent 30% of max for one and 70% max for the other, but the aerobic demand of a 10:00/mile pace is essentially a fixed value.

The ACSM prediction equation for running is VO2 = (Speed(meters/min) x 0.2) + 3.5 . To calculate Kcal/hr, you divide the VO2 by 3.5 to get METs and multiply METs times body weight (in Kg).

There are no other qualifiers or factors included.

Yet I constantly see references that claim that if you continue to work out at a certain intensity over time you will burn fewer calories at that same intensity. Again, ACSM makes no such distinction that I am aware of. It is obvious that a new exerciser will experience greater mechanical inefficiency (and I supposed physiologic inefficiency as well) but that is a transient effect--research studies often include familiarization sessions, but usually only a few are needed.

There is a logical fallacy in that argument in that, if calorie burn continues to drop over time, one would eventually expend no energy at all, no matter how intense the activity--which is obviously absurd.

I think that many people make the mistake of interpreting the drop in HR that occurs at any submaximal workload after training with a drop in calories. That's due to the fact that they are mistakenly assuming that HRMs measure calories. If one does not update one's VO2 max setting in an HRM then, yeah, the calories burned number will drop, but it's a bogus number.

I have looked for some research on this topic--i.e. evidence of a drop in caloric expenditure over time by an individual doing a consistent aerobic intensity in a simple activity such as running--but have not seen any, although my time to search is limited and my search skills are rusty at best.

Have you seen anything that supports or disproves this idea?

there have been numerous studied done on the drop in VO2 max during regular aging. Here's a few

http://jap.physiology.org/cgi/content/abstract/68/5/2195

(note the links at the bottom, I'm not going to link them all here)


and also here's one that shows the affects of other factors on exercise efficiency.

http://content.onlinejacc.org/cgi/content/abstract/47/5/1049

This is just a couple, but there's been quite a bit of study on this. Most agree that Age (especially as we pass the 50 year mark) , weight, and "practice" play at least some roll in increased (or decreased) calorie expendature during exercise.