Posted by: Elle | 2007/08/09

Positive & negative resistance training

Please could you explain the difference between positive and negative resistance weight training and how the two work together? Thanks for your time!

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Our expert says:
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Hi Elle

I'll do my best, it's quite a tricky concept when you get down to the fine level details (in fact, the actual mechanics of what is happening to the muscles is still not 100% known - it's just a theory), but the practical application I can attempt to explain.

Positive work is also called concentric work, which refers to what the muscle does during a contraction. In this type of contraction, the muscle shortens while the load is lifted - positive work is done on the load. So picking up a barbell and doing the bicep curl is positive work - you apply a force to the load, the muscle shortens and the load is moved.

Negative resistance training is called eccentric work, and here the muscle lengthens during the contraction (which is a difficult concept to grasp). But what happens is the the load torque (or force, for simplicity's) sake is greater than the muscle torque and the muscle lengthens. This happens when you lower the weight. So for example, having lifted a weight, you then lower it back down - this is negative work.

In terms of practical application, bear in mind that the alternative to lowering the weight in a controlled manner is to let momentum take it down. But if you control the movement down, by concentrating on the lowering part of a lift, it's been suggested that you will be adding another phase to the training altogether. For example, in a normal bicep curl (to use a basic exercise), you would lift in about 1 to 2 seconds, lower in 2 to 3 seconds. In negative training, you might take 5 to 10 seconds to LOWER the weight. This controlled lowering is stressing the muscle differently, providing it with an eccentric stimulus that ultimately will improve strength. The jury is however out on this one, it's a bit controversial.

one that that negative training does do, however, is reduce the risk of injury. Most muscle injuries happen during the eccentric part of the muscle cycle - whether it's running, lifting etc. So by training eccentrically, you can really develop neural and muscle control that may reduce the risk of injury, and that's obviously a big benefit.

So that's how you would incorporate negative training into your programme - focus on the lowering as much as you do the lifting.

Good luck

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