What Running Actually Improves

In our previous post,“Running Builds Strength… But Not Much", we unpacked a common misconception.

Simply running more will make you stronger.

It doesn’t. At least not in the way most people define strength.

So the obvious next question is:

What does running actually improve?

Because it does drive adaptation. Just not always in the way people expect.

Running is not strength training

Let’s briefly revisit the key point.

Running does not meaningfully improve maximal strength in trained individuals.

If you measure:

• 1RM strength

• Isometric force

• Dynamometry

You generally won’t see significant improvements from running alone.

When changes do occur, they’re typically:

• Small

• Short-term

• Seen in untrained individuals

So if your goal is:

• Higher force output

• Muscle hypertrophy

• True strength gains

Running isn’t the tool for the job.

What running actually improves

Where running does have a strong effect is in a different set of qualities.

1. Tendon stiffness and elastic return

Running is a repeated stretch-shortening cycle.

Each step:

• The Achilles stores energy

• Then releases it

This allows runners to:

• Recycle energy

• Reduce metabolic cost

• Move more efficiently at a given pace

Over time, running can influence:

• Tendon behaviour

• Elastic energy utilisation

• Coordination of the muscle-tendon unit

But here’s where it gets important.

Most of the strongest evidence for increasing tendon stiffness comes from:

• Heavy resistance training

• High strain loading

These expose the tendon to:

• Higher forces

• Slower loading rates

• Greater mechanical stimulus for adaptation

Running is different.

It involves:

• High repetition

• Relatively low to moderate strain per step

• Limited variation in loading

So rather than dramatically increasing tendon stiffness, running likely:

• Maintains tendon mechanical properties

• Improves how effectively elastic energy is stored and returned

• Refines the interaction between muscle and tendon

In other words:

• Running probably doesn’t build a stiffer tendon in the way heavy strength training does. It improves how well the system uses the tendon it already has.

This is still highly valuable for performance. But it is a different adaptation to what most people assume.

2. Reactive strength (not maximal strength)

Running involves:

• Rapid force production

• Force absorption and re-use

This sits closer to reactive strength.

You will see:

• Short ground contact times

• Better stiffness control

• Improved rhythm

This is why good runners look springy, not necessarily strong.

But again, there is nuance.

Running does involve reactive qualities, but it does not maximise or significantly develop them in the way plyometrics or sprinting do.

Ground contact times in distance running are:

• Longer than sprinting

• Lower force

• Lower rate of force development

So rather than building high-level reactive strength, running likely:

• Maintains reactive qualities

• Improves efficiency within a narrow bandwidth

• Refines timing and coordination of force application

Running improves how well you use reactive strength, not necessarily how much of it you have.

3. Local muscular endurance

This is one of the clearest and most consistent adaptations to running.

Running improves:

• Fatigue resistance

• Repeated submaximal force production

• Oxidative capacity of muscle

Particularly in:

• Calf complex

• Soleus

Which works continuously at relatively high loads for long durations.

This is where running is very specific to the adaptation.

Distance running exposes muscle to:

• High repetition

• Prolonged time under tension

• Submaximal loads

This directly drives:

• Increased mitochondrial density

• Improved capillarisation

• Greater oxidative enzyme activity

So rather than just maintaining this quality, running is actually a primary driver of it.

There is also some shift in muscle fibre characteristics.

Endurance training can lead to:

• A transition toward more oxidative profiles

• Particularly within type II fibres, shifting toward more fatigue-resistant behaviour

This is often described as a shift from:

• Type IIx to Type IIa

Rather than a large change from fast to slow muscle.

So again, the theme holds.

Running does not dramatically change the muscles you have. It improves how fatigue-resistant that muscle becomes

That said, it is still specific.

Running improves:

• Endurance at the intensities and patterns you train

It does not necessarily improve:

• High load endurance

• Strength endurance under heavy resistance

• Capacity outside of the running context

4. Neuromuscular efficiency

Over time, runners become more efficient movers.

This includes:

• Better coordination

• Reduced unnecessary muscle activity

• Smoother movement patterns

Resulting in:

• Lower energy cost

• More consistent stride

• Less wasted motion

This is closely tied to running economy.

But again, it is specific.

Running improves efficiency:

• At the speeds you train

• Within your habitual movement patterns

It does not necessarily transfer broadly to:

• Other athletic tasks

• High force or high velocity movements

So this is less about building new capacity and more about refining an existing skill.

5. Bone loading (with limitations)

Running does load bone.

But it is:

• Repetitive

• Predictable

• Same direction

Bone adapts best to:

• Novel stimulus

• High strain rates

• Multidirectional loading

So while running can help maintain bone health, it is not the most effective way to build it.

Bone does not just respond to load. It responds to a new load.

This is why:

• Plyometrics

• Strength training

• Multidirectional sport

Play a much bigger role in improving bone robustness.

The key takeaway

Running improves:

• Elastic qualities

• Reactive strength in a specific and limited way

• Muscular endurance

• Movement efficiency

It does not significantly improve:

• Maximal strength

• Hypertrophy

• High force production capacity

Why this matters clinically

This is where mistakes happen.

If a runner presents with:

• Calf strain

• Achilles tendinopathy

• Bone stress injury

And the solution is just more running

You are reinforcing what they already have.

Not addressing what is missing.

The better question

Instead of asking:

“Is running good for strength?”

Ask:

“What qualities is this runner lacking?”

Because often it is:

• Maximal strength

• Load tolerance

• Capacity outside of running

Simply running more will make you stronger.

It doesn’t. At least not in the way most people define strength.

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