Strength Sensei 101: Strength Curves: Part 1

Strength Sensei 101

Strength Curves: Part 1


More insights into the pioneering training methods of Charles R. Poliquin


Charles R. Poliquin has written extensively about working the muscles throughout a full range of motion, even if this meant using less weight. For squats, he would recommend squatting to where the hamstrings covered the calves, rather than performing the partial movements performed in a powerlifting competition. The benefits? Consider the results of 4x Olympian Jud Logan.

When Logan first came to see the Strength Sensei in 1991, he had been plagued with knee pain for the previous eight years. His squatting depth was slightly above parallel. After six weeks of performing full squats, his knee pain was resolved, and he said his sitting position in the turns improved. Three months later, Logan set the indoor world record in the 35-pound hammer.

While achieving muscular balance with full-range exercises is critical to athletic performance and orthopedic health, there are times when partial-range exercises should be used. This brings us to the topic of strength curves and resistance curves.

A strength curve describes how much force you can produce at specific joint angles; for example, most people are stronger at the finish of a deadlift. There are three types of strength curves:

  1. Ascending Strength Curve. A movement that enables you to produce more force as a joint is extended (and the muscle is contracted). A squat is an example of an exercise with an ascending strength curve, as you can lift more weight at the top of the exercise (when you start to bend your knees) than at the bottom.
  2. Descending Strength Curve. A movement that enables you to produce more force as a joint is flexed. A chin-up is an example of an exercise with a descending strength curve, as you are strongest at the start of the movement (when you start to pull yourself up).
  3. Ascending-Descending Strength Curve. A movement that enables you to produce more force at the mid-range position, between flexion and extension of a joint. A standing biceps curl is an exercise with an ascending-descending strength curve because you are strongest at the mid-range position of the exercise.

A resistance curve is the amount of resistance an exercise provides at various points of the movement. For example, most leg extension machines have a resistance curve that increases as the muscles are shortened, such that it is relatively easy to start the movement but difficult to finish.

Arthur Jones is the founder of the Nautilus exercise equipment company, and his machines were the first to address the issue of strength curves. Jones believed that overloading all areas of an athlete’s strength curve was necessary for maximal strength and muscular development. Rather than using several exercises with different resistance curves to achieve this overload, he looked for ways to change the resistance curve during an exercise.

To accommodate an ascending strength curve exercise such as a bench press, Jones tried attaching chains to the level arms of his machine, such that as the exercise was performed and the chains lifted off the floor, the resistance would increase. As chains were impractical, he eventually came up with the idea of using shell-shaped pulleys (thus inspiring the name of his company, Nautilus) that would alter the resistance as the exercise was performed.

Expensive Nautilus machines aside, the most practical way to overload specific all areas of an individual’s strength is with a power rack. The power rack has adjustable safety bars that allow you to set the barbell at a specific portion of the exercise to target each point of a strength curve. For example, you can set the pins so that the bar rests just a few inches short of lockout. If your best bench press is 150 pounds, you might be able to perform 200 pounds or more working through this partial range.

If you want to focus on the sticking point of an exercise (where you commonly fail during an exercise), you can set the power rack safety bars at that point and target that area. Bob Hoffman was the publisher of the popular newsstand magazine Strength and Health and was a prolific writer. Hoffman wrote about this topic in his magazine in 1961 (Hoffman, B. Revealing the New Power System, Strength and Health. 1961 Nov; 29: 30-31) and in a book he wrote published in 1962 called Functional Isometric Contraction.


Besides building bigger and stronger muscles, partial range training can be considered a form of sport-specific training for many sports. In Science and Practice of Strength Training (1995, Human Kinetics), Sports Scientist Vladimir M. Zatsiorsky says that to become more sports-specific, athletes can often benefit from including partial range exercises. For example, Zatsiorsky said whereas an elite volleyball player should perform 60 percent of their squats in a semi-squat manner, an elite ski jumper should only perform 20 percent of their squats in this manner. However, he said both athletes at the beginner level should not perform any semi-squats.

The Strength Sensei was especially fond of using partial range exercises to disinhibit the nervous system to stimulate higher levels of strength, and he credits 1961 IFBB Mr. Universe Chuck Sipes for popularizing this concept. At a bodyweight of 220 pounds, Sipes could bench press 570 pounds, squat 600 pounds, and barbell curl 250 pounds!

After performing bench presses in a conventional manner, Sipes would support heavier loads in a lockout position for four sets of 10-second reps. What this accomplished was that it could temporarily shut down a tension/stretch receptor in the tendons called the Golgi tendon organ. The Strength Sensei would take advantage of this effect by supersetting a set of conventional bench presses (at 85 percent of maximum for 5 reps) with a set of heavy supports (with 120-130 percent of maximum for 8 seconds). Three supersets were performed in this manner, after warm-up.

And understanding strength curves and resistance curves will help take your workouts to the next level of optimal performance and physical development. Part 2 of this series will explore several practical ways to apply this knowledge. (TSS)

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