We have recently removed our Cybex trice extension equipment. A number of our members have complained stating that it was the only trice machine that they used because it isolated the muscle. I agree at the complete isolation concept but have shown them some exercises to replace this machine as long as they concentrate on the form. One gentleman stated that he is unable to get full range of motion using the rope attachment on the Cybex Multi-Station. I explained that the best movement is small, from 90 degrees to 180 degrees at the elbow. I told him that any further movement is mainly stretching the muscle; the power comes form the smaller ending to the arm extension. He is thoroughly questioning me on this. Can you help?
This is a good question of biomechanics. At 90 degrees of elbow flexion, the triceps moment arm (the shortest distance from the axis of rotation, to - AND perpendicular to - the point of resistance) is the longest, which means this is where the muscle is the "strongest." This is what I'm assuming you meant by "the power comes from the smaller ending to the arm extension." (NOTE: "Power" training has little to do with this discussion. Power training by definition is concerned with reducing the AMORTIZATION phase of the muscle contraction spectrum in a given movement pattern.) This is fitting because at 90 degrees, this is also where the moment arm of the load is the longest, likewise making it the "heaviest." Now, does this mean that one should not eccentrically flex the elbow past 90 degrees during exercise? Absolutely not. If a "full ROM" can be achieved safely, then go there. After all, we visit that ROM every day in life.
The reason your member "is unable to get full range of motion using the rope attachment" brings me to my next point. Direction of resistance will ultimately dictate the muscle fibers used here. In a pushdown, when the elbow is eccentrically flexed as far as possible, the direction of the resistance of the rope no longer matches the direction the triceps are pulling. Perhaps you could instruct your member to slightly flex at the hips (only if lumbar neutral can be maintained) while maintaining the elbows at the side. This will increase the resistance encountered when the elbow is fully flexed eccentrically (see image below).
All mechanics aside, I need to make one more point. If this is a member who has been using these fixed, uniplaner, artificially stabilized machines with "chronic" regularity for years, this may be a great opportunity for you to introduce him to some basic integrated training techniques (i.e., integrated flexibility, core and balance training. In this day and age, with all the information that is available to fitness/performance professionals, it must be universally understood that traditional hypertrophic goals and constant machine training make up only a small segment of a well balanced fitness/performance periodization plan and by no means qualify "fitness" - hence the old phrase, "perceivably fit, but unhealthy").
For example, check the member's ROM of active shoulder flexion. I would be willing to bet that he is restricted too far less than 180 degrees. You might explain to him that training his triceps in isolation, in the same position/speed/intensity over time has contributed to his restriction, which ultimately can lead to shoulder and/or low back discomfort. Perhaps he is experiencing some of this already!?
References & Recommended Reading:
- Norkin & Levangie. (1999). Joint Structure and Function. (3rd ed.)
- Purvis, T. Simon, M. (2000). Resistance Training Specialist. (Level 1 & 2 Course Manual)
- Clark, M. (2002). Essentials of Integrated Training Series. (www.PTontheNET.com )