Revealed: Does Cardio Kill Flexibility?

You often see a lot of runners pull up a leg and start stretching after finishing their routine jog. 

Why do they do this? 

Is this because running decreases flexibility?

Also, it the amount of running you do or the type of running you do that matters?

…And what about cycling and other endurance sports – do these make you inflexible?

Let’s take a closer look to discover the answers:

Your body is an incredible organism that can adapt to many new demands and stressors you place upon it.

On the flipside, your body also likes normality and will look to maintain the demands and stressors it is most frequently exposed to – especially when it comes to flexibility and range of motion.

This comes with two implications:

  1. If you use increasing ranges of motion frequently enough, your body will adapt.
  2. If you don’t use, you lose

What does this mean? 

If you regularly repeat movements to increase your range of motion, your body will adjust itself to these movements by making you more flexible – in fact it actually adds sarcomeres within your muscles lengthways in order to accommodate this (see our previous articles for more on this). 

On the other hand, if you shorten your range of motion consistently enough, your body will actually make the relevant muscles shorter and subtract sarcomeres from within your muscles (Williams et al. 1988). 

Yes, the ‘use or lose it’ saying is true in a literal material sense.

Research from Orlikowska (1991) demonstrated that your nervous system’s controls of length and tension in your muscles are set to the values you repeat most often or most strongly.

Hence if you do cardio endurance activities such as cycling or distance running which do not use a full range of motion in your joints, your body will adapt accordingly to these ranges and make you less flexible over time (without adequate stretching or flexibility intervention).

In fact, even if you do common exercises like push-ups with lots of volume (daily push-up challengers take note), you will get a similar reduction in range of motion in your chest, shoulders and arms.

You’re now starting to see why gymnasts don’t do any distance running.

“But wait, don’t gymnasts do sprints? Isn’t that running?” you say.

Correct – they do. This is because sprinting is specific to their sport (Vault and floor routines) but it also requires greater stride length and more maximal ranges of motion (at the hips and knees) than lower intensity distance jogging.

So what is the answer if you’re an endurance athlete/exerciser? How much stretching and what type of stretching works best for avoiding decreased flexibility over time? 

It turns out that some forms of stretching are definitely better than others. 

The typical dynamic stretching before and static stretching after a training session will help and can still apply.  

However, you are missing out on a lot of potential performance gains and injury prevention if you just leave it at that. 

Studies by Fridén (1984) showed that long-term exercise, in which muscles tense as they are stretched (contract-relax stretching), caused changes in the length of the muscle fibres via adding new sarcomeres (think of these as muscle building blocks for now). 

Handel et al. (1997) also conducted a study that showed significant changes in the strength of its subjects throughout an increasing range of motion in athletes who introduced regular contract-relax stretching into their programs. This also produced additional sarcomeres and longitudinal growth of the athletes’ muscle fibres – yes, they literally materially lengthened their muscles.

What is contract-relax stretching and why is it so effective? Contract-relax stretching is where you get a muscle into a stretched position and then contract it (in order to inhibit the stretch reflexes and make the muscles feel safe).

It is an amazingly effective form on stretching because the muscles learn to adapt and become stronger through increased range, whilst also learning how to better circumvent their neurological inhibitions (the stretch reflexes) that have been imposed on them by the body. 

Again, this is another way that your body is telling you that if you use it (the range of motion), you won’t lose it.

If you’re an endurance athlete (or anyone else for that matter), you should seriously consider dedicated stretching sessions and programming that incorporate contract-relax stretching that is commensurate to your needs. 

Knowing one’s individual requirements will require some coaching oversight and prescription. However, this should not deter you and you would be silly to leave the huge potential benefits lying on the table. 

If you would like a highly effective, targeted program, then reach out to one of our expert coaches with your concerns and needs via the contact form below.

This is the 2020’s not the 1980’s! Start taking your flexibility seriously and start seeing it as more than a casual after training activity. It is a training modality all of its own (just like strength, speed and endurance).

Don’t put your flexibility training off any longer! You’re not only preventing injuries with proper flexibility training, but you’re also improving performance! 

If you have been following us for some time, by now this should be a no brainer. Reach out to us today – it’s free to listen. 

Again contact one of our coaches and put yourself on the flexibility fast-track:


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