Thread by @Gareth_Sandford

Have you heard soft running surfaces reduce injury risk?

I thought that made sense

But the answer is not that simple

Learn how changing surface impacts:

• Muscles

• Tendons

• Bones

🧵

Disclaimer!

Speed plays a huge role on effect of surface interaction

This is controlled in many studies but not realistic

I.e typically people would run slower on sand than pavement

Here’s what you need to know from @BiomechMax @Brad_Beer chat on @tppshow1 ⬇️

Factors affecting training response to surfaces:

• Running style

• Foot strike

• Ground reaction force profile

• Control of stiffness

• Footwear (for more on this see ⬇️)

https://mobile.twitter.com/Gareth_Sandford/status/1382062261745770498

Different surfaces to consider:

• Pavement (asphalt, concrete)

• Packed down trails

• Track

• Treadmill

• Grass

• Sand

https://twitter.com/stevewillis_NZ/status/1053150111595810816?s=20

Body demands change on different surface types

When you run on sand (soft)

• You get no energy return from the ground

• The sand dissipates

• Note non-wet sand different to wet sand

Pavement

• Ground is highly responsive

• Because it doesn’t deform

If you maintain the same speed on sand and pavement

Muscles work harder on the sand

Because you get less return on touch down

This creates more mechanical work

And is hard on the muscles and tendons

Running on sand

Can increases achilles tendon injury risk 10 X

Compared to running on asphalt

researchgate.net/publication/33…

On pavement you strike the ground

And all forces come back

Propelling you forward

Less muscle work is done compared to sand

So far we have covered

Hard surfaces

• All forces come back

• Less muscle work done

Soft surfaces

• Muscles and tendons do more work

• More demanding on energy systems

But that is just half of the story...

On pavement

• More bone loading

• Greater musculoskeletal demand

https://twitter.com/BiomechMax/status/1230885907433218052?s=20

On Sand

• Surface feels soft

• But uneven surface does not mean soft is better

• The increase in muscle force may contribute to more bone loading

When we run on sand

We regulate extra muscle demand by reduction in speed

NOT the surface

Perhaps this is a what is protecting us!

We aim to minimize energy cost

When moving between surfaces

This is why we walk to the store

Rather than MC hammer walk to the store

Interaction between shoes and strike pattern is confusing

Tease out:

• Which foot strike pattern (rear – mid – fore- foot)

• With which specific shoe

Why does this matter?

https://twitter.com/Gareth_Sandford/status/1440031686855593999?s=20

Most shoes are geared towards forefoot striking

To asses shoe impact you should hold constant either:

• The shoe or

• The foot strike pattern

If you are a rear foot striker

Transitioning into softer shoes

Be aware whilst this may lessen knee stiffness

It will increase ankle stiffness

Consider alongside your injury risk profile

Findings from @UofMHealthSci

After controlling for

• Shoes

• Stride pattern

• Speed

Peak forces were not different between surfaces

Where does this leave us?

TL: DR Summary

Does a soft running surface reduce injury risk?

• We lack consensus

• Soft surfaces increase muscle and tendon work

• Hard surfaces increase bone loading

• Strive for variance in stimulus

• Manage surface based on individual profiles

Thanks to @BiomechMax @Brad_Beer @tppshow1

For the discussion on a challenging topic

Full episode ⬇️

https://twitter.com/Brad_Beer/status/1451839739514920960?s=20

If you enjoyed this thread:

1. Comment/send me a DM to let me know what resonated

2. Share a link to the first tweet ⬇️

https://twitter.com/Gareth_Sandford/status/1453442225384214530?s=20