Muscle Stiffness: The Best Exercises for Runner Training

A truly strong runner doesn’t need to expend large amounts of energy at every step to move their body weight; a small initial energy expenditure can be enough to then take advantage of muscular stiffness and bounce effortlessly to the finish line.

Stiffness? Bouncing? What are these concepts?

I didn’t invent the concept of stiffness, but science explains it.

And I’ll try to explain it to you.

In fact, in this article, you will learn:

• What the concept of muscular stiffness is;
• Why it is important for a runner;
• Why you need to possess the correct balance between stiffness and muscle extensibility;
• Suitable exercises to improve strength;
• Technical exercises suitable for beginners;
• Technical exercises suitable for experienced runners.

While you are running, the muscles of your body (along with tendons, bones, and neuromuscular fascia) behave like an elastic band: they release a great deal of energy after being slightly stretched.

Imagine what happens when the musculotendinous units that allow you to move are first elongated (albeit under tension) and then released: the potential elastic energy that has been accumulated is transformed into mechanical work, i.e., energy for your movement.

This concept is crucial for a runner!

In the moment between one step and the next, your muscles are elongating (i.e., an eccentric phase occurs, the muscle fibers stretch) and, along with the tendons, are storing potential elastic energy.

Once you touch the ground, the muscles contract (concentric phase, the muscle fibers come closer), but they do not need to require large amounts of energy from the body to perform the next step because they can utilize part of the potential energy that has been accumulated in the musculotendinous unit.

They thus have “free” energy available: simply by having good stiffness, i.e., a balance between stiffness and elasticity, they can move forward with significant metabolic savings.

Let’s see a practical example to understand better.

As you well know, in the movement of running the main player is the Achilles tendon, which during the landing phase can stretch by 6%, i.e., almost 1.5 centimeters compared to its initial length, and return about 90% of the potential elastic energy (stored in the form of mechanical work) in the subsequent push phase.

Thanks to this trick, elastic energy is made available to you in the form of free metabolic energy!

That’s why I wrote earlier that it’s important to know how to bounce thanks to stiffness.

In the athletic training of a runner, it is a component that must be constantly sought and stimulated: it allows running faster while expending less energy!

In fact, to ensure that the foot returns the maximum amount of potential elastic energy, it is necessary that each ground contact provides an optimal response to the stresses.

A correct degree of stiffness improves and reduces ground contact times and the energy expenditure of the running action, which thus becomes more effective; if this were not the case, at the same running speed, you would have a higher metabolic expenditure, thus you would struggle more and would not be able to maintain this specific speed for much longer.

The optimal degree of stiffness is obviously specific to the type of sport you are practicing (clearly for an ultratrailer it is lower compared to a double track specialist) and represents a fundamental point for the optimization of many sports movements.

However, be careful. You must be careful not to make this mistake!

It is necessary to seek a correct balance in this physical parameter:

• if your musculotendinous unit possesses high stiffness it will tend to deform little and will require a large amount of force to perform the movement, in other words, it will be able to store little elastic energy and return it in very short times. Moreover, a too rigid tendon increases the risk of injuries;
• if, on the other hand, your musculotendinous unit turns out to be too extensible, it means it will undergo a large deformation, the transfer of power from the muscle to the bone occurs over a longer time, with a reduction of power that is partly dampened by the elasticity of the tendon itself. To return to the starting position, it will take a long time, thus dispersing much of the energy it had stored.

The ideal compromise for an athlete is to possess elastic musculature that can deform enough but is at the same time stiff enough to return to the starting condition in a short time.

Possessing the correct degree of muscular stiffness, the transmission of power occurs in less time with a consequent increase in the same, with the technical gesture that is performed in less time and with greater energy.

To try to improve the degree of stiffness, you should include in your training exercises aimed at the explosive-reactive strength of the lower limbs: the more strength you can generate with this elastic response, the less energy is required to perform that movement.

The muscle must have an excellent ability to generate and withstand high tensions, that is, it must be able to express a certain force at a precise moment. If there is a lack of a strength base, the elastic behavior cannot be effective.

Since it is a cyclic movement that you will repeat thousands of times during races, it means that it will have a significant impact on the total energy expenditure and therefore on the result you can achieve!

For this reason, one of the exercises I recommend you include in your training program is the weighted squat jump.

For example, you can use a barbell placed on your shoulders and loaded with an appropriate weight.

But be careful not to get carried away by enthusiasm and make the mistake of performing technically incorrect movements, or performing too few repetitions or leaving too few minutes of rest.

If you want to improve muscular stiffness, the main characteristics that the reinforcement training you will perform in the gym should possess are these:

• from 2 to 3 exercises;
• load from 30 to 50% of your maximum;
• from 3 to 5 sets per exercise;
• from 12 to 30 repetitions per set;
• consecutive and explosive execution;
• recovery from 3 to 8 minutes.

Remember to modulate these indications based on your current fitness state and your sporting background.

I recommend in the first workouts to start with 3 sets of 12-15 repetitions for each exercise: based on how your body reacts to these stimuli, you can consider increasing some parameters, gradually and paying attention to recovery.

Now let’s see what can be done outside the gym, perhaps in a phase of the warm-up or as the protagonist of a real training session.

I have diversified the exercises I propose because they are not as simple as they might seem at first glance.

If you are already a strong runner for years, but believe you can further improve your stiffness, you can watch this video where I show some specific exercises that you can include in your workouts.

I recommend performing these movements on a flat and sufficiently hard surface, asphalt or athletic track. It is better not to perform them on a lawn or on sand because you would disperse too much potential energy and would not have help from the ground in the reactive response you are looking for.

Here is the video:

As you have read, muscular stiffness is a fundamental component of the physical equipment of a runner and as such must be constantly trained in order to always seek the best possible performance.

If you are interested in having more information, if you have doubts, or want to ask me questions about the advice you just read on training muscular stiffness, write to roberto@undertraining.ch or request your free consultation with him using the button below.

Happy running!