Are your feet noisy when you run? Why Physios say this is not a good sign.
As a Physio I can often hear what someone’s gait is like before I even see it. In fact, this can be mildly annoying and hard to switch off. I’ll be out walking the dog, and on hearing a jogger behind me, the cogs start spinning. My brain automatically starts predicting whether it’s a man or a woman, how big they are, how fast they’re running, how experienced a runner they are, and how fatigued they are. This might seem like a lot to understand just from the sound of footfall - and just to be clear, I don’t always correctly predict what I’m going to see when the jogger runs past. But more often than not I’m bang on.
None of this is a superpower. It’s clinical training in gait analysis, plus years of paying attention to how noisy people are with their feet, in various settings.
At the Movement Clinic in Newcastle, we work with many dancers. You can hear the quality of their landings on the studio floor. (And you can definitely tell when there’s a ballet class full of people running around in pointe shoes!).
Another thing that tuned me in to quiet feet was rock climbing: I’d hear coaches say it to the kids, and I’d try it too. Quiet feet mean you’ve placed your toe on a hold and given the rubber time to smear or wedge its way into giving you grip. A noisy foot is a foot that bounces off the hold a little and can’t grip.
Runners with quiet feet are more efficiently controlling the forces of locomotion, and so less energy escapes in the form of noise. Noise and running are like heat from petrol engines. The job of a car engine isn’t to get hot; it’s to propel a car. Heat is a byproduct of burning fuel, and the engine loses a huge amount of the energy it burns as heat, so car manufacturers must go to great lengths to get rid of that waste heat with a radiator and coolant.
Even less efficient runners convert their energy into forward motion far better than the best fossil-fuel engine. About 65% of landing energy goes into forward motion.
Still, how do I know someone with noisy feet is running less efficiently, and what do I mean by “efficient”?
Some physics helps.
Firstly, the law of the conservation of energy. Energy is neither created nor destroyed; it is simply transformed. So every calorie, joule, watt (or whatever you want to measure it in) during every foot landing must be redirected into propulsion. It’s just like the car engine, which must redirect heat into propulsion. A less efficient runner loses some of their energy to noise. An inefficient engine, in fact, all fossil fuel engines, loses about 80%-90% of the energy they burn to heat and noise.
Next, the equation which is explains what “power is”:
P (Power) = W (Work Done) / T (Time)
Work divided by the time taken; that’s power. Noisy feet when running suggest you're generating more power.
You might think this is a good thing, and sometimes it is. For example, when I have people do running drills, I usually want to hear their feet during certain parts of the drill. I want to know they’re putting force through the ground in a dynamic way… which makes a noise. But that’s drills, not actual running. As a rule, the faster the run, the more noise is acceptable. A sprint, like the running drill, can be thunderous. That’s ok because a lot of power is being produced and it doesn’t last long. A thunderous 10k is a different matter entirely…
Let’s unpack power a little more. We could put 2 people, same body weight, same height and limb lengths, on a curved treadmill, and both could run at 145 watts, one noisy, one quiet. One thundering along, one sounding like a cat. What’s a quiet runner doing that a loud runner isn’t? Well, they aren’t using less power - this is constant at 145 watts.
Let’s look at the cat. Cats are famously stealthy, which is why YouTube videos of them falling off things are so funny, because it’s unusual. Imagine a cat weighs 3kg. We can drop the cat from 2m; a cat will land almost silently, and it won’t bounce. Now let's drop a 3 kg rubber hex dumbbell. It’ll make a serious thud. It’ll also bounce quite high. Same forces involved, very different outcomes.
What’s clearly going on is shock absorption. Both hit the ground with roughly the same force, but the cat absorbs and redirects the energy. The dumbbell does not. A telltale sign is energy leaking as sound.
Interestingly, the cat is not really made of shock-absorbing materials. A cat is made of about 70% water. Water doesn’t compress. Unlike a gas, there are no spaces between molecules, which can be compressed during an impact. In this sense, it’s like a solid. A cat is also made of around 235 bones (depending on tail length); around 13% of its weight, and bone is a solid, which also doesn’t compress. The last 17% is minerals and fats, which also don’t compress. Yet the cat, like a human, can absorb landing shock almost perfectly.
A rubber-headed dumbbell is made out of shock-absorbing material, but it’s noisy and uncontrolled.
Ok, this needs some qualification - animals, us, cats, do have rubber-like shock absorbers which work in the same way as the dumbbell. The fat pad in our heels; the meniscus in our knees; the discs in our spine (this is more or less it; there aren’t many more). They don’t compress (they can’t), but they displace forces and flex, like rubber, using elastic expansion.
More importantly, though, our feet and legs use elastic bands throughout the body that stretch as you land and ping back, turning the energy you put into your system into propulsive force. Imagine dangling a rubber band from your finger, and something lands in the bottom of the loop, so it stretches, then pings back. That’s how the cat’s body works, and that’s how we work. Not really through compression like your car suspension, but more like a steady-cam, where weight and springs counterbalance each other to create stability amongst movement.
As a runner, the more you absorb the force and convert it smoothly, the less noise escapes.
In the quiet runner, the force is absorbed across a larger structure.
Less work (W in our equation) is being done at each specific spot. Instead, all that work is being dissipated across the foot, calf, knee, buttock, spine, shoulders and arms.
At the Movement Clinic, you’ll often hear us talk about rowers as an analogy. Imagine 4 people in a rowing boat. If one rower doesn’t pull hard, the other three must pick up the slack if they’re going to keep travelling as fast.
Similarly, the noisy runner usually has something in the kinetic chain which is not lengthening, like an elastic band, to absorb force. They’re less like a steadycam. There’s more instability and less smooth redirection. They’re relying more on the few compressive structures we have - especially the knee meniscus and discs - and less on the counter-weighted elastic structure of the fascia, muscles, tendons and ligaments. And this is what you hear, as their feet thud like a dumbbell.
The outcome is not necessarily a slower runner. But it is a runner who might be more prone to pain and injury - especially in the knee and lower back.
What can we do?
If you are in pain, see a physiotherapist (do your research and find a good one!). If you’re in the Northeast of England, I can vouch for us at the Movement Clinic (of course!). If you’re not struggling just now but are concerned about how thunderous your running is, there might be a footwear fix (every runner’s favourite topic: shoes). Marshmallowy, built-up shoes can weaken your feet and make you rely on the shoe to do the work. You therefore lose the real performance and endurance gains these shoes offer because you’ve deconditioned your feet and probably your deep calf and shin muscles.
So use these shoes as a performance enhancement, not a crutch: save the marshmallow shoes for race day, and use less squashy shoes for training.
Pavement is unforgiving, and asking your limbs to absorb every impact is a lot. Concrete isn’t much like the forest floor and grasslands our feet evolved for. Horses need shoes so their hooves don’t wear down, and similarly we can usefully use a little bit of cushioning in our shoes, just not so much that we weaken our feet. I like Altra and Topo, which have wide toeboxes that let the toes do their thing.
You might also want to do a little gait retraining by running in barefoot shoes for short distances. Build this up slowly, because it takes time to adapt. Unless you only run cross-country, I wouldn’t recommend barefoot shoes as anything more than daily wear and gait retraining.
References
Cavagna, G. A., Saibene, F., & Margaria, R. (1964). Mechanical work in running. Journal of Applied Physiology, 19(2), 249–256.
Derrick, T. R., Hamill, J., & Caldwell, G. E. (1998). Energy absorption of impacts during running at various stride lengths. Medicine & Science in Sports & Exercise, 30(1), 128–135.
Franklin, S., et al. (2015). Barefoot running: A systematic review of kinematic, kinetic, and case study literature. Sports Medicine, 45(7), 965–983.
Komi, P. V. (2000). Stretch-shortening cycle: A powerful model to study normal and fatigued muscle. Journal of Applied Biomechanics, 16(3), 299–306.
Lieberman, D. E., et al. (2010). Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature, 463(7280), 531–535.
Nigg, B. M. (1997). Impact forces in running. Current Opinion in Orthopaedics, 8(6), 43–47.
