Stretching Your Tendons – Is It Really Bad?

You may have heard that you should only stretch your muscles and not your tendons whilst stretching (or doing any other form of exercise). Its purported that if you stretch your tendons, you will cause irreversible damage and promote injuries.

Is this advice sound? How do you stretch tendons and should you avoid this?

To answer these questions, we first need to have a look at the structure of our muscles and the tissues that surround them. If we do this, we will grasp a lot of their limitations and the extent of their function.

Understanding your structures and the implied principles, will do wonders for your body and your training progress.

Your Muscle Structures:

If you didn’t know already, your muscles are encased (similar to the way an electrical cord is an encasement of live wires) with a fibrous connective tissue sheath called epimysium.

Your muscle fibres are arranged in bundles called fascicles and are surrounded by similar fibrous tissues called perimysium and endomysium (the latter encases each muscle fibre). See the picture below:

Ref: https://training.seer.cancer.gov/anatomy/muscular/structure.html

In the context of exercise, why is this important? The tension generated by the muscle fibres is transferred to the fibres of these connective tissue. Tendons are dense and sinewy extensions of these tissues. Tendons not only attach your muscles to your bones, but they also have unique performance properties. The stiffer your tendons, the better the use of elastic energy in your stretch-shortening cycle (SSC) movements – this is provided you have the required range of motion (Kubo et al. 1999).

What is the SSC cycle exactly? It’s something you use all the time when you run, jump, walk and make use of elastic energy within your tissues to make movements easier and more effective. It’s like stretching a rubber band and then releasing it – see the diagram below:

Ref: https://www.frontiersin.org/research-topics/10437/the-stretch-shortening-cycle-of-active-muscle-and-muscle-tendon-
complex-what-why-and-how-it-increase

Trade off or trade up?

If we have stiffer muscles and tendons, won’t it pay to keep doing resistance training and keep our tissues stiff in order to take better advantage of the SSC? Let’s look at the bigger picture to answer this.

One of the best ways to build tendon strength (and muscular strength) is through using resistance training – see our previous info piece for more on this:
https://performancerevolution.com.au/do-bigger-muscles-make-stretching-harder

The evidence is quite clear though, that doing resistance training can really tighten up muscles and connective tissues over time. In fact, if you do just resistance training without any form of stretching, you will increase the stiffness of your muscles and surrounding tissues which will increase the passive resistance in these tissues – likely causing a loss of range of motion (ROM) and SSC potential as a result.

If your ROM is less than that required for taking full advantage of the SSC, then it is likely beneficial for you to increase your ROM at the cost of lowering the stiffness of involved muscles and tendons (Wilson et al. 1992).

However, before you resolve yourself to this trade off, let’s look at some more research to realise that it doesn’t have to be either/or.

Resistance exercises with movements of maximal amplitude and active ROM, that develop both strength and flexibility, are an effective means of increasing length and extensibility of tendons and connective tissue sheaths of muscles (Platonov 1997).

But wait, there’s more – if you do dynamic resistance training together with static stretching, this will give you the benefits of increased tendon stiffness (and increased reuse of elastic energy) in the SSC, without altering or increasing the passive resistance to the stretch (Kubo et al. 2002a).

What does all this mean? It means that if you implement static stretching along with resistance training (preferably using full ROM), you can increase the tension capabilities of your tendons (and therefore your SSC potential) without negatively affecting (and even improving) your movement quality and range of motion.

How does this work? Back to our muscle structures – you can permanently elongate tendons and connective tissue sheaths, with minimal structural weakening by implementing low-force but long-duration stretching (i.e. static stretching) when the temperatures of the tendons are more than 39’C.

When are your tissues this warm? Post exercise is a very reliable time for this to occur. This is an ideal situation to do your form of resistance training (preferably using full ranges of motion wherever possible) followed by static stretching, where you maintain your stretches while your tendons and sheaths cool down.

Your stretches must be performed at the range of motion at which muscle fibres pose less resistance than the fibrous connective tissue – the window of time straight after training is usually the best timeframe for this to occur.

If you do this correctly, you will produce longer term, positive structural changes in your tendons and other muscular tissues.  Your tendons and other tissues will become longer but also stronger at the same time. This will increase the tension capabilities of your tendons (and therefore your SSC potential) without negatively affecting (and even improving) your movement quality and range of motion.

This practice of stretching and strengthening your body throughout a full range of motion will not only better your body’s performance over time, but it will also help ensure you avoid potential overuse injuries and setbacks.

So is stretching tendons bad? Yes – but only if done incorrectly.

If you’re serious and ready right now to learn exactly how to stretch your tissues to improve your body and its functionality (rather than degrade it), then simply fill out your details below to talk to one of our expert coaches about a personalised flexibility program. Our time-tested, science-backed, proven programs will put you on the fast-track to reducing pain, increasing recovery, and getting flexible! Get in touch with us today and we will show you what is possible for your body:

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