Knuckle Rub - Dangerous Practice or Quick Growth Technique

Knuckle Rub

Listen to your Body for Aches and Pains

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The knuckle rub. While I do not intend to belittle the originators of this unorthodox concept, I do feel a need to offer scientific opposing argument. This concept is not new. In all the time it has been practiced, to my knowledge no one has taken a stand in opposition to its supposed benefits. Knuckle rubs have not been in the limelight for quite some time now, so why should I even bother addressing the issue? Well, I saw a young man in the gym where I train being tortured by his training partner's knuckles and elbow. Usually I keep my comments to myself in the gym, but this time 1 had to say something. I ended up spending a great deal of time pleading my case against knuckle rubs to what turned into a small crowd. Make no mistake. In my opinion this training tool for size and strength increase can actually be more injurious than beneficial. After standing around for 10 to 15 minutes listening to me put on a clinic overview on the subject, Debbi, my wife and lifelong training partner, told me I ought to write on the topic. So, if you disagree with the logic behind my position, it's all her fault.


When the concept was first introduced it seemed quite logical. Trainees practicing this knuckle-rub technique were boasting incredible results. If I am not mistaken, one individual reported an upper-arm circumference increase of over half an inch in only one day! For those of you unfamiliar with this controversial training tool, allow me to explain.

The proper application of the knuckle rub, as I understand it, is to fill the target muscle with as much blood as possible (the pump). You accomplish this pump by doing several lightweight, high-rep sets. Once you have established the pump, you manipulate the target muscle into its fully stretched position. The deep fascia, which is the elastic connective tissue surrounding bundles of fibers and muscle groups, is now stretched to its supposed limit. While it is in this position, the intense rubbing of the knuckles deep down into the tar-get muscle results in the fascia being stretched beyond its original limit. This then provides a larger compartment within the fascia for future tissue growth. On the surface this theory sounds comprehensive and quite believable.


First of all, the fascia surrounding a bundle of muscle fibers will expand and enlarge sufficiently to accommodate the temporary buildup of fluids during a workout (the pump). When the pump is gone during recovery between workouts, the bundle of fibers reduces back to normal size. During recovery and anabolism the fascia should be capable of expanding to at least the size it was while pumped during training. This means there should always be sufficient room in the muscle compartments to allow for continued growth without the need for further stretching of the fascia.

Second of all, the fascia itself may incur sufficient damage from the pressure and friction applied during this rub to cause inflammation and the increased presence of fibroblasts. This temporary swollen condition known as fasciitis could easily be mistaken as growth.

Lastly, there have been reports of bruising associated with knuckle rubs. Visible bruises result when damage is caused to vessels under the skin, allowing blood to hemorrhage into tissue spaces. In addition to these bruises, deep invisible bruises (contusions) are also quite likely being caused by knuckle rubs. The hemorrhaging intramuscular vessels cause fluids and waste materials to pool in the muscle compartments. Since a large number of damaged vessels are lymphatic and venular, fluids and waste that accumulate cannot be efficiently removed and transported back into the main vascular tree. This occurrence is clearly indicated by the temporary superficial increase in the size of the target muscle after the application of knuckle rubs, which last as long as a few days. In my opinion this type of damage can in no way be construed as productive.

Give this issue careful consideration before adding knuckle rubs to your training. Until next time ... eat right and exercise smart!

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