The term “High Intensity Training” has entered our fitness vernacular over the last few years due largely to the emergence of CrossFit and a variety of boot camp style exercise regimens, brands, and classes. However, the use of the term “intensity” to describe these exercise modalities is a misnomer; and its an important matter of nomenclature.
Interestingly, in the early 1970’s, Arthur Jones, the founder of Nautilus Sports Medical Industries, touted the importance of exercise intensity. But Arthur’s definition was far different than the definition ascribed by exercisers today.
Arthur’s definition of intensity referred to the level of intensity that an individual used during a strength training exercise.
Specifically, Jones was referring to the level of tension placed on a muscle during a strength training exercise. To maximize intensity, Arthur encouraged body builders, athletes, and eventually, all of us, to perform a set of strength training exercise to the point of “momentary muscle failure.” The point in which another “perfect” repetition could not be performed. A perfect repetition meant that we shouldn’t alter body position or increase the speed of movement so that we incorporated momentum. Striving to continue the set to muscle failure maximizes the number of muscle fibers that are recruited. Over the past 40+ years, the scientific community has now adopted both Jones’ definition of intensity and the importance he placed on muscle failure. In fact, training with this high level of intensity, that is, continuing strength training sets to the point where another perfect rep is impossible, is the recommendation of virtually all of the scientific and medical establishment.
However, when most people think about “intensity” in 2017, they picture something far different from what Arthur described.
In 2017, intensity seems to be defined by bloody and calloused hands; loud music; swinging of all kinds (your body, a kettle bell); grunting; flipping over a tractor tire; and orthopedic pain. To be clear, Arthur is rolling over in his grave at this. Exercise INTENSITY is central for health and fitness benefit. But it looks nothing like what many exercise enthusiasts assume. Exercise intensity involves a focused effort in placing tension on muscles and muscle groups until we are no longer able to complete a repetition with perfect form. The tension on the muscle is high, but because momentum is minimized, the force imposed on the joints is very low and thus safety is maximized. This is the foundation of safe and intelligent exercise. The 2017 popular definition of intensity is more aptly… Reckless.
In January of 2013, I wrote the following Fit Tip about Intensity: https://www.discoverstrength.com/intensity-defined/