Doesn't using weights increases intensity a LOT more that just what can be accounted for by increasing your bodyweight? Because of the leverage they get at the end of your arm, they cause a lot more stress than just an addition to bodyweight?

Posted to by Larry

Well, your point about leverage is valid, and that's one of the key problems with stress about the back.

However, if you look at data on weights and aerobic exercise involving measurement of oxygen uptake during the activity, you'll find that the increases in oxygen uptake are proportional to the increase in bodyweight.

The numbers I was referring to came from studies conducted at Auburn University and Adelphi University looking at the difference in energy cost of step aerobics routines with and without the use of handheld weights.

If you're going to argue with this, think first. Lets say you put on a 20# weighted belt. Do your regular program. That's the equivalent of increasing your bodyweight. Do the same program with 10# dumbells in each hand, and you'll get much different results.

The differences here are primarily perceived exertion. The sustained contractions of the muscles increase the peripheral resistance to blood flow, increasing the heart rate and the blood pressure disproportionately to the exercise intensity. It's been my observation that perceived exertion is more closely linked to heart rate than to energy cost when it comes to aerobic activity, though it is also possible that higher lactate levels may be generated with the weights than without as well. Lactate levels could also increase the RPE.

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