Jul 20, 2009

Q&A: Machines and Variable Resistance

I've been working out at my home club and they got some new machines from Hoist Fitness with "ROX" technology, which basically means your seat moves as you curl or row or whatever. It feels neat and according to the weight stacks, the change in resistance per plate is nonlinear and differs depending on the user's weight.

From a kinesiological point of view, are there any benefits to this, either in results or just reducing stress on joints or something? The description from their website is here:

Hoist Fitness Roc-It Technology

I had not heard of it. It is certainly an interesting design. My assumption is that the nonlinear change it weight is consistently an increased load toward end range of motion. There are certainly some pros to equipment of this nature, but in the end the benefits tend to be joint, muscle, user specific. One con...an person who is overweight may not have a matching strength to body-weight ratios and may find this equipment difficult to use or set up appropriately.

Nautilus was the first on the market with stuff like this (variable resistance) with their cam systems a few decades ago. Claimed it was the miracle machine as load was supposed to perfectly mimic the human muscle strength curve (weaker to stronger to weaker). Problem is that everyone has different limb lengths, tendon attachment points (therefore varying leverages), as well as different muscle and movements do not always follow the weak-strong-weak strength curve (i.e. squatting tends to be a weak to strong movement if measuring from the bottom of the movement up to the standing finish). I can't tell from the website if this equipment expands/modifies these problems without using it. However, worst case scenario is that it is a nice biomechanical variation for your muscles.

In the end, I have tended to be more and more of a fan of "free-weight" types of movement. Reason being is that I think it is important for everyone to gain control over their bodies moving through space since that is still primarily how we interact with our environment (though more technology and machinery could change that in the years to come). Balance, stability, proprioception, etc. are things that are simply not developed at all--or as well--on machines. There are benefits to machines. But I always encourage machine use to be more of a beginner mode or a mode that is used in the minority with advanced exercisers.

Movement is good...quality movement in free space is better.

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