Why Ankle Stiffness Is One of the Key Contributors to Sprint Speed in Children

When most parents think about making their child faster, they think about running more or harder.

Think about the feet.

Every fast runner has one thing in common—they produce force into the ground through strong, springy ankles.

When an ankle lacks strength and stiffness, it slightly collapses every time the foot lands. Although this collapse might only be a few millimetres, it happens hundreds of times during a run.

Instead of directing force forwards, some of that force disappears down into the ground.

Think of trying to jump on a soft mattress versus a trampoline. A trampoline returns energy. A mattress absorbs it.

Your child’s ankle works the same way.

The Chain Reaction

A weak ankle doesn’t just affect the foot.

It changes everything above it.

When the ankle collapses:

One small weakness at the foot affects every step the child takes.

Running is a chain. If the first link is weak, every link above it is affected.

These cues encourage:

which are all characteristic of faster sprinting.

Three Parts of Great Ankle Stiffness

1. Strong muscles

The calf muscles (gastrocnemius and soleus) and the muscles at the front of the shin (tibialis anterior) provide the strength needed to stabilise the ankle.

Without strength, there is no stiffness.

2. Elastic spring

Speed isn’t only about strength.

It’s about how quickly the ankle can absorb force and rebound off the ground.

The best sprinters spend very little time on the ground.

They hit the ground…

…and bounce straight back off it.

3. Force into the ground

Children often improve instantly with one coaching cue.

I simply tell them:

“Hit the ground hard like you mean it.”

Then I ask them to run softly.

Every single child notices the difference.

Running with intent helps children produce more force into the ground, which leads to better acceleration and speed.

Simple Coaching Cues That Fix Running Technique

Instead of giving children complicated instructions, I use simple cues.

Interestingly, simply asking children to look forwards often improves their posture immediately.

The hips rise, the chest becomes taller, the core naturally activates, and their entire running position improves.

Sometimes the biggest improvements come from the simplest cues.

Exercises We Use

To build stronger ankles we regularly include:

Strength

Plyometrics

Technique drills

Supporting muscles

Strong hips help keep the knees tracking correctly, allowing force to transfer efficiently from the ground through the entire body.

Don’t Forget Hill Sprints

One of my favourite exercises for developing strong feet and ankles is hill sprinting, jumping and hopping.

Running uphill naturally places greater demand on the calves, Achilles tendon and foot muscles.

It teaches children to push into the ground, improve ankle stiffness and produce more force while reducing the braking forces seen during flat sprinting.

Hill sprints are a simple but incredibly effective way to build stronger, more powerful runners.

The Research

Research consistently shows that:

Key references

1. Plyometric training makes children faster

A 2025 systematic review including 17 studies and 587 children found that plyometric jump training significantly improved:

The authors concluded that plyometric training is an effective way to improve sprint performance in children

2. Better ankle stiffness means better sprint mechanics

Research on sprint biomechanics shows that faster runners have:

When the ankle behaves like a stiff spring instead of collapsing, more energy is returned into the next stride instead of being lost.

Coaching cue:

“Bounce off the ground.”

3. Strong calves are one of the biggest contributors to speed

Recent biomechanics research highlighted by Stanford University’s Human Performance research shows that:

produce more than half of the upward and forward propulsive forces during running.

Elite runners rely much more on their ankles than recreational runners. Recreational runners rely more on their quadriceps, which increases braking forces.

4. Children should do plyometrics

The latest evidence shows appropriately supervised plyometric training is safe and improves:

in children and adolescents.

What actually happens when the ankle collapses?

When the ankle collapses into excessive dorsiflexion after foot strike:

Conversely, a stiffer ankle allows the Achilles tendon and calf muscles to store and rapidly release elastic energy, producing a quicker, more forceful push-off.

  1. Wu, H., Li, S., Lai, J., Bian, W., Ramirez-Campillo, R., Sáez de Villarreal, E., & Zhao, Q. (2025). Children’s sprint and jump performance after plyometric-jump training: A systematic review. Journal of Sports Science and Medicine, 24(1), 52–74. https://doi.org/10.52082/jssm.2025.52
  2. Weyand, P. G., Sternlight, D. B., Bellizzi, M. J., & Wright, S. (2000). Faster top running speeds are achieved with greater ground forces not more rapid leg movements. Journal of Applied Physiology, 89(5), 1991–1999.
  3. Brughelli, M., & Cronin, J. (2008). A review of research on the mechanical stiffness in running and jumping: Methodology and implications. Sports Medicine, 38(10), 819–845.
  4. Bohm, S., Mersmann, F., & Arampatzis, A. (2015). Human tendon adaptation in response to mechanical loading: A systematic review and meta-analysis. Sports Medicine, 45(1), 111–123.
  5. Lloyd, R. S., Oliver, J. L., Hughes, M. G., & Williams, C. A. (2012). The effects of 4-weeks of plyometric training on reactive strength index and leg stiffness in male youths. Journal of Strength and Conditioning Research, 26(10), 2812–2819.