Brisk Walking Exercises – Are They Useful?

Brisk walking - beneficial or just a fad?

First of all, No, No, No…..This is not to imply that walking as an exercise is not useful. It definitely is, and perhaps is the only option for keeping fit in an urban and office-going setup. Now, look at the title again. What I am asking is whether brisk walking, which is advised by medical practitioners and exercise gurus, is useful. Or, to put it differently, what are the advantages conferred by brisk walking over the relaxed one? I fail to understand how walking in a faster pace would burn more fat in an appreciable way. May be I am wrong, then I would be extremely grateful is somebody could clarify the position.

Basically, the trouble arises when I remember some of the fundamentals of school physics, like work, energy and power. If you want to move a body having some weight over a distance, you have to perform work. Energy is the capacity to do work and numerically the same and have same units (joule or calorie). Power is the rate of doing work. If you want to move the same object in half the time it took in the first case, you have to double the applied power.

Now, come back to the walking exercise. Suppose your body weight is 80 kg (at least I don’t need to suppose it as it is painfully evident!) and you want to walk a distance of 1 km. The work and hence energy needed to transport a body of 80 kg over a distance of 1 km is the same whether you do it in ten minutes or one hour (by definition, work = force x distance. Time is not factored in). Fat burning is expressed in calories which is a measure of energy consumed. So, if fat is burned in direct proportion to energy, what difference it would make if you walked slowly?

On the other hand, we must be aware that doing the same work in less time need more power. Using more power in the same volume would mean additional heat losses in the muscles. If you run a machine at full throttle, it would warm up to a higher degree than the idling state. Brisk walking needs more power and more heat loss. Heat is a form of energy, but I think the fraction that is lost as heat is very small as compared to the energy expended in the act of walking itself. Otherwise, sweating would not be enough to cool you and you might be in need of a radiator!

So, why the pundits ask people to walk fast when it does not provide for more fat burning than slow walking, which is much more enjoyable?

Or, am I wrong?