Tendons

Angelo Marcone

What are Tendons?

A tendon is a cord of strong, flexible tissue, similar to a rope. Tendons connect your muscles to your bones. Tendons let us move our limbs (arti).

They also help prevent muscle injury by absorbing some of the impact your muscles take when you run, jump or do other movements.

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.

What does a tendon do?

When you contract (squeeze) your muscle, your tendon pulls the attached bone, causing it to move. Tendons essentially work as levers to move your bones as your muscles contract and expand.

It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tension.

However, over the past two decades, much research has focused on the elastic properties of some tendons and their ability to function as springs.

so tendonds are not static, they can also generate force. (not all but some tendons)

Energy storing tendons can store and recover energy at high efficiency. For example, during a human stride, the Achilles tendon stretches as the ankle joint dorsiflexes. During the last portion of the stride, as the foot plantar-flexes (pointing the toes down), the stored elastic energy is released. Furthermore, because the tendon stretches, the muscle is able to function with less or even no change in lenght, allowing the muscle to generate more force.

Muscle Contraction: During a human stride, the muscles, such as the calf muscles, contract. This contraction generates force and energy.

Energy Storage in Tendons: As the ankle joint dorsiflexes (when the foot moves upward), the Achilles tendon stretches, storing some of the energy generated by the muscle in the form of elastic potential energy.

Energy Release: When the foot plantar-flexes (pointing the toes down), the Achilles tendon recoils, releasing the stored elastic energy. This energy assists in moving the foot, reducing the need for the muscle to generate the same amount of energy during this phase.

Muscle Efficiency: Because the tendon is doing some of the work by releasing stored energy, the muscle can function more efficiently. The muscle doesn't need to change length significantly, allowing it to produce more force with less energy expenditure.

In 1 Step (Energy Storage and Release):

As you take the first step, the Achilles tendon stretches when your foot makes contact with the ground and you roll forward onto your toes.

During the push-off phase of that first step, the tendon releases the stored elastic energy, which helps propel your foot off the ground.

In some cases, the recoil of the tendon can provide a significant portion of the force needed for motion, reducing the workload on the muscle.

As your muscles contract, it is actually the tendon which causes your bones to move, safely transmitting the force generated by muscles as well as acting as shock absorbers from sudden or intense movements.

Tendons are stiffer than muscles and have great strength. For instance, the flexor tendons in your foot can handle more than eight times your body weight.

What is the anatomy of a tendon?

Tendons are mostly collagen, one of the most abundant proteins in your body. Tendons also contain blood vessels and nerves.

The collagen fibers in a tendon group into:

Primary fiber bundles (subfascicles), the smallest bundle.

Secondary fiber bundles (fascicles) made of groups of subfascicles.

Tertiary (third) fiber bundles containing groups of fascicles that form the tendon itself.

Understanding tendons and ligaments

its important to know the difference between tendons and ligaments. Tendons connect muscles to bones, facilitating movement, while ligaments connect bones to bones, providing joint stability. Both play an important role in supporting the musculoskeletal system

And Muscles?

While it’s possible to see changes to the muscle bellies after just a few days of proper strength training with appropriate intensity, tendons and ligaments will take much longer.

The reason for this is that there is a much more limited blood supply to the connective tissue than to the muscles.

I wrote this article just for answer a simple question:

Can You Strengthen Tendons?

The short answer is yes. But, when compared to changes in muscle tissue, which can take just days to improve, the tendon’s structural tissue can take weeks or months to adapt. One study showed that it took two months before tendon stiffness improved, and this also included changes in collagen structure and synthesis. This is why tendon and ligament injuries take longer to heal — there is limited blood supply going to these connective tissues. Thus, it also takes more time for a tendon to adapt to training stress compared to muscles.

How to Strenght Tendon?

1. Eccentric Training

Eccentric training can be done with lighter weights or bodyweight where the high forces are generated through a lengthening (eccentric) contraction (such as landing on the floor from the top of a box jump into a deep squat or when you lower your heels back down after the raise in a slow and deliberate manner, that is an eccentric movement.) or with heavier weights and a focus on lowering them as slowly as possible.

Multiple studies have been done on eccentric training and tendon stiffness. These studies found that tendon stiffness does not change, or improves minimally, with body weight alone. Instead, weighted protocols on a single leg resulted in better improvement in tendon stiffness.

A few examples of eccentric training exercises that can help strengthen tendons and ligaments include:

Eccentric heel raises

Single-leg squats

Single-leg deadlifts

2. Plyometrics

https://www.youtube.com/watch?v=i1Bp8ZgdJ5w&t=33s

Explosive movements like plyometrics — such as squat jumps, single leg hops, depth jumps, box jumps, and quick feet step-ups — may help build tendon strength and make your legs feel a little more snappy, as long as you don’t overdo it.

Plyometrics use the tendon’s recoil response to execute explosive movements. Take, for example, a single-leg jump. The Achilles tendon lengthens and then releases energy as it recoils or shortens. Over time, this action becomes more efficient.

Plyometrics should be phased in and applied gradually to one’s strength training program. A 14-week study of plyometric training determined that, over time, there was less energy dissipating as heat and more energy being applied to the recoil of the tendon, allowing for an increase in the rate of our movements.

Examples of plyometric leg exercises that can reduce your risk of injury can be found here.

Plyometric training can have a significant impact on performance and injury resistance, but due to the high loads and sometimes complex movements associated with plyometric training, it is critical to develop a deliberate progression plan based on your sport and your experience with this type of training.

3. Isometric Training

Isometric contractions occur when the muscle is held in a constant or static position. Examples of isometric exercises include wall sits, calf holds, planks, or any position that you can maintain and hold for an extended time.

One study concluded that isometric training can provide short-term pain-relief benefits in the middle of the competitive season. Isometric training may also be beneficial at the beginning of a strength training program or rehab for improving stabilization. This would be very important before doing heavy resistance training as you need to know how to put your joints in a stable position. So while structurally heavy resistance training and eccentric exercises have been shown to be more effective in building overall tendon stiffness, isometric training can be more effective targeting the healthy fibers in a tendon with previous tendinopathy or that is otherwise painful so that it can begin to remodel itself and eventually reduce or eliminate pain