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Understanding the Cam Effect - by Matthew Romans

In previous blog posts I have written about some of the exercise machines we have in our Total Results studio. If you take a closer look at these machines, you will likely see an oddly-shaped plastic or aluminum structure over which a kevlar belt runs around its perimeter and attaches to a movement arm. This structure is called a cam, and it is what provides variable resistance throughout the range of motion of the exercise. Why is this important? The cam is a critically important component of exercise equipment design and is one of the foundations of our exercise protocol. Having an understanding of the cam effect sets the Total Results exercise philosophy apart from the rest of the industry.

Prior to the 1950s, the only tools available for weight training were barbells and dumbbells. You could certainly get stronger using barbells and dumbbells, but there were inherent limitations; you most likely needed a spotter for many exercises (like a bench press or squat), and it was harder to progressively add small increments of weight. Two exercise machine companies emerged in the late 1950s: Universal (1957), and Marcy (1959) each came out with their own version of all-in-one exercise stations. Universal was the more recognizable brand. Their machines tracked on a round pulley that did not vary the resistance at all. From a convenience standpoint it was an improvement upon the barbell (my high school weight room contained a Universal multi-exercise station). Arthur Jones, who had been a filmmaker and animal trader, created the first Nautilus exercise machine in 1970, largely because he saw a way to improve upon the limitations of the barbell and Universal machines. Jones inherently understood that human muscles are stronger in some positions and weaker in others, so there was a need for variable resistance. In his memoir, Jones credited his oldest son Gary (who later went on to create Hammer Strength exercise machines) with solving the problem of how to provide variable resistance with the cam. Since the cam was eccentrically-shaped and looked like a nautilus shell, that was how the company got its name. After selling Nautilus in 1986, Jones formed the MedX corporation, initially to produce medical-grade testing machines before making general exercise equipment. MedX machines (we have several of them) are leverage-driven and do not have a cam like Nautilus machines do and are not connected to a belt (since their weight stacks have no guide rods), but are very well-designed.

Ken Hutchins (the founder of our exercise protocol) was an employee at Nautilus during the 1970s and 1980s, and held a variety of responsibilities for the company. In addition to supervising (with his wife Brenda) the Nautilus Osteoporosis Project at the University of Florida, he also worked very closely with Jones in equipment prototype design. Hutchins eventually understood that most of the older generation of Nautilus machines were engineered based on a relatively fast speed of movement (2 seconds raising the weight, 4 seconds lowering the weight), and in some cases (such as the vintage Leg Curl machine), the cam effect was backward, meaning that the resistance was too heavy in the most contracted position and too light at the starting position. After leaving Nautilus in the late 1980s, Ken began manufacturing his own equipment (and many of his machines can be found in our studio) under the moniker of Super Slow Systems. These machines are an intellectual leap forward from the Nautilus cams; they were designed for a much slower speed of movement (10 seconds lifting, 10 seconds lowering) and with much less friction between the guide rods and weight stacks. The cam effect on these machines can and should vary from one exercise to the next, based on the involved musculature. While the Leg Curl has a fairly radical cam fall-off, the Chest Press feels less radical.

What does this mean for your workout? The inherent mechanical limitation of the barbell is that there is no way to achieve variable resistance, so the weight will be too heavy in some positions and too light in others. We want to be consistent with timing, which is the matching strength with resistance. The resistance should be heaviest when your muscles are in their strongest position (usually the start of the positive phase of the movement), and lightest in their weakest position (usually the most-contracted position). This results in your muscles being loaded/targeted more effectively, and translates into a more thorough inroad and stimulus. Theoretically, if the cam is properly designed, you should reach momentary muscular failure at random positions in the range of motion from one workout to the next (although I usually find myself hitting failure on the Leg Press in the bottom out position). Further, any movement faster than approximately 5 seconds renders the cam effect virtually meaningless, which is one reason we emphasize a very slow speed of movement (approximately 10 seconds in each direction).

At Total Results, our exercise protocol is centered around our equipment design, and while you can use our protocol on regular gym equipment, the effect doesn't come close to what you get working one on one with us in our ideal exercise environment. Come experience the difference today!

Posted July 11, 2019 by Tim Rankin