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Dear RF,

I am not an exercise physiologist so I am send these ideas from experts. If you want the actual formulae they used I recommend their book to you, or any other text on the subject. Thank you for you interest.

From: Exercise Physiology. McArdle, Katch and Katch. Second Ed. Lea&Febiger Energy Expenditure During Walking, Jogging, Running, and Swimming (pp163) Summary

1. Energy expenditure can be expressed in gross as well as net terms.  Total or gross values include the resting energy require-ment, whereas net energy expenditure is the energy cost of the activity per se excluding the resting value.

2. The relationship between walking speed and oxygen consumption is essentially linear. Walking surface also has an influence, because walking on sand requires about twice (1.8) the energy expenditure as walking on hard surfaces. The energy cost is proportionally larger for heavier people.

3. It is more economical, from an energy standpoint, to jog-run rather than to walk at speeds greater than 8 km - h-1.  The difference between jogging and running depends on the fitness level of the participant; a jog for one person may be a run for another.

4. The total caloric cost for running a given distance is about the same whether the pace is fast or slow.  For horizontal running, the net energy expenditure is about 1 kcal -kg-' - km-'.

5. It generally costs less energy to shorten running stride and to increase the number of steps in order to maintain a constant running speed rather than to lengthen the stride and reduce stride frequency.

6. Overcoming air resistance accounts for 3 to 9% of the cost of running in calm weather. This percentage increases considerably if a runner attempts to maintain pace while running into a head wind.

7. Children generally require significantly more oxygen to transport their body weight while running compared to adults. This relatively lower running economy accounts for the poor endurance performance of children compared to adults with similar aerobic capacity.

8. The energy required to run a given dis-tance or speed on a treadmill is about the same as that required to run on a track under identical weather conditions.

9.The energy expended swimming a given distance is about four times greater than that expended running the same distance.  This is because the swimmer must expend considerable energy to maintain buoyancy and overcome the drag forces that impede movement.

10.There are significant differences between men and women for body drag (well, duh), mechanical efficiency, and net oxygen consumption during swimming.  Women swim a given distance at about 30% lower energy cost than men.

11.Elite swimmers expend fewer calories to swim a given stroke at any velocity.  The optimal water temperature for most competitive swimming is 28 to 30 C (82 to 86'F).

George L. Dixon, Jr., M.D.