Tendon Injury Prevention
Let us take a moment to review tendons and types of tendon injuries. A tendon is an area or junction in the body where a muscle attaches to a bony region. The tendon is a thick fibrous tissue that allows the bones or the
limbs to move as the muscles contract and tighten. They also help prevent muscle injury by acting as shock absorbers when you run and jump. Over time, these tendons are subject to overuse injuries, poor circulation due to aging and lack of movement or arthritis. These injuries most often occur when a muscle is pulling dysfunctionally on a bone due to poor movement patterns or due to poor muscle activation and proper contraction.
Your body contains thousands of tendons. You can find tendons from your head all the way down to your toes. The Achilles tendon, which connects your calf muscle to your heel bone, is the largest tendon in your body.
Tendons are highly resistant to tearing but aren’t stretchy. This means they can be easily injured when strained (stretched to point partial tearing of rope fibers) and may take a long time to heal.
What do we know: Prevention through strengthening is possible
Tendon strengthening has been very helpful for preventing injuries even though tendon tears and varying levels of inflammation are very common in therapeutic practices. Preventing these injuries can take time but may be very important if you are an athlete that does any sort of repetitious motions (racket sports, running, golfing, etc.).
Tendons respond much slower to healing efforts than muscles for a couple of reasons. One, they have lower levels of circulation when compared to muscles. There is also a sheath material encasing the tendon that can also become inflamed and further lessening the perfusion of the tendon further. There are blood vessels in the sheath surrounding the tendon, but the only intrinsic blood flow is from the muscle spindle (stretch receptor) and the golgi tendon organ (force tolerance receptor). The limited blood flow equates to slower healing, and the collagen deposition takes longer as well.
Muscles take ~ 4 weeks to show signs of growth (hypertrophy) tendons take weeks to months to "stiffen" or grow. “Stiffness” is the term defined by research groups to show tensile strength for tendons. The variables range from gender, type of strength training, and consistency of resistance training.
It is generally understood that overall resistance can improve tendon resilience, however, because of the low profusion for the tendon the higher rep range provides more opportunity for increased blood flow and provides low level resistance to challenge the tenocytes to provide more collagen and elastin to the tendon, essentially training the tendon to be more "stiff."
Tendon strengthening can also improve your overall strength and force output. Since the Golgi tendon regulates the amount of force the muscle may exert, training the the tendons in a way to prime the Golgi tendons to really allow the muscles to more force safely and efficiently.
For more in depth reading:
Now lets talk about the actual Perscription of this:
Rep ranges are recommended anywhere from 50-100 to really improve tendon tensile strength (Kurtz). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4041869/
Beginning at the 20 rep range does show benefit, there is evidence of fibroblast activity at any resistance stage, but going into the higher rep ranges (that 50 to 100) will give more opportunity to bring more blood flow to the tendon.
For those of you just beginning your tendon work, we recommend starting at the lower end and as you gain more strength and improve tensile strength, increasing rep range to 100 overtime but keeping resistance low.
If you are into the nitty gritty:
Here’s the summary of our research & recommendations:
Tendon tears are very common and lucky for us, there are ways we can prevent injury and improve our strength along the way!
One may ask, why focus on strengthening tendons? Don't they get stronger along with our muscles and regular levels of strength training? To an extent, the answer to this is indeed, yes they do.
Tendons work differently and here's why we need to have specific exercises in conjunction with our normal resistance training:
1.) They have less blood supply compared to muscles. There are two types of blood flow that tendons receive, extrinsic and intrinsic. Extrinsically, sheathes that cover tendons provide nutrients that profuse through to the tendons. Intrinsically, the muscle spindle and Golgi tendon organ provide nutrients through their individual blood supply. Muscles have many capillaries and blood vessels throughout the fibers and therefore get more blood flow. Overall, this means there is slower growth due to less access to nutrients.
2.) Muscles grow and adapt quicker compared to their tendons. Muscles usually begin to hypertrophy as quickly as 3-4 weeks. Tendons take weeks to months to improve tensility or "stiffness"
As stated before, general resistance training can improve tendon resilience, however, because of the low profusion in the tendon, staying in the higher rep range provides more opportunity for blood flow to permeate the tendon and provide nutrients. The lower resistance provides low level stress on the tendon to challenge the tenocytes and fibroblasts to provide more collagen and elastin to the tendon, thereby training the tendon to be more "stiff" or stronger.
So how many reps should you do? Kurtz suggests that you should do anywhere from 50-100 reps. However, there are benefits for tendons beginning as low as the 20 rep range. \
So for beginners in tendon work I recommend starting at the lower end and as you gain more strength and improve tensile strength then we can increase rep range to 100 but continue to keep resistance low.
Tendon strengthening comes with more benefits than just injury prevention. It can also improve your strength and force output. Since the Golgi tendon stops us from using our muscles to their full potential we can "train" the Golgi tendon to allow the muscles to exert more force without giving out. This can also improve your the endurance capabilities of the muscles we're training.