Do Carbon Plates Work, and Should You Train in Them?

Two hundred and fifty pounds, and a wall of them, and everybody in your club has a pair.

The reasonable question is whether they work. The more useful question, which almost nobody asks before they buy, is what happens to the load the shoe is taking off you, because it does not disappear.

Nothing in a shoe reduces the total work. It moves it. The only thing worth knowing is where it moved to, and whether that part of you is ready.

Yes, They Work

Let us not be contrarian about this. The effect is real and it is one of the better documented findings in running of the last decade.

The headline figure everybody quotes is a four per cent improvement in running economy, meaning you use around four per cent less oxygen at a given pace. The wider literature is a bit messier and more honest: improvements in the region of roughly three to four per cent are typical, with meaningful variation between individuals, and a minority of runners get very little.

It is also not the plate on its own. It is the whole system working together, a very light and very resilient foam, an aggressive rocker geometry, and a stiff plate that changes the lever at your forefoot. Pull any one of those out and most of the effect goes with it, which is why a stiff plate in an ordinary midsole does approximately nothing.

The benefit also scales with speed. The faster you run, the more the system gives back. A runner covering the marathon leg of a full distance race at a genuinely slow pace is getting considerably less from these shoes than the marketing implies, and paying full price for it.

Where the Load Goes

This is the part the shoe wall does not mention.

The stiff forefoot and the rocker change how and when your calf works to control the ankle. For a lot of runners that means a greater tensile demand on the Achilles, and a change in how the midfoot is loaded.

The pattern that has emerged in the clinical literature is reasonably specific: navicular bone stress injuries, Achilles tendinopathy, plantar fascia problems and calf strains, associated with reduced cadence, overstriding and increased rearfoot eversion, and concentrated in runners who were not conditioned for the shoes before they started racking up miles in them.

I want to be fair here, because it cuts both ways. For some runners, particularly those who already have a cranky calf, the shoe genuinely reduces the load and feels like relief. The mechanism is not fully settled and the individual response varies more than anybody selling them would like to admit.

What is not in doubt is the direction of the risk: these shoes ask something different of your tendons and your midfoot, and tendons and bone adapt on a slow clock. You cannot introduce them the way you introduce a new t-shirt.

The Triathlon-Specific Problem

Everything above applies to runners. Triathletes have an additional problem that does not get discussed at all, and it is a serious one.

You do not start your run fresh. You start it on legs that have been in one position for two to five hours, with a gait that is going to degrade further over the next hour, and with calves that have been working in a very different pattern on the bike.

A shoe that demands more of the calf and Achilles, and that punishes overstriding and low cadence, is meeting you at precisely the point in the day when your form is falling apart and your cadence is dropping. That is not a general risk. That is a specific mechanism, arriving at the worst possible moment.

It does not mean do not race in them. It means the brick run is where you find out, not race day.

How to Actually Use Them

The consensus among sports medicine people and coaches who deal with the aftermath is consistent and boring, which is usually a sign it is right.

Race day and a small number of key sessions. Everything else in a stable, unplated trainer. Somewhere around one run in five or six is a sensible ceiling, and if you are coming back from a calf or Achilles problem it should be lower than that.

Introduce them the way you would introduce hill sprints or plyometrics, which is to say gradually and with a plan. Start with a short session at moderate pace. Give it a few days and pay attention to what your calves and Achilles say the following morning, because tendons are late reporters and rarely complain during the session itself.

Then, and this is the one triathletes skip, do at least two race-pace brick runs in them before you race in them. Off the bike, at the effort you intend to hold, for long enough that your form starts to go. If your calves are screaming at twenty minutes off the bike in training, that information is worth every penny of the shoe.

Rotate the rest of your running across a couple of different, ordinary shoes. Varying the load across your week is one of the cheapest injury-prevention tools available and it costs you nothing but shelf space.

Keep the Number in Proportion

Three or four per cent is genuinely worth having. It is also worth setting next to the other numbers in your race.

You will lose more time than that riding the first thirty minutes of the bike leg twenty watts too hard. You will lose considerably more than that getting your fuelling wrong and walking two aid stations. And you will lose all of it, and your season, to a navicular stress fracture in March that came from doing every easy run in a shoe designed for race pace.

Buy them if you want them. Race in them. Just do not train in them because they make your easy runs feel quick, which is the actual reason most people end up running in them daily and the exact behaviour that produces the injuries.

Who Gets Least Back

Worth knowing before you spend the money, because the benefit is not evenly distributed and nobody selling them will tell you this.

The system returns energy in proportion to how much you put into it, so it rewards speed. A runner going through the middle of a full distance marathon leg at a pace that is closer to a jog is compressing that foam far less than the athlete it was designed around, and getting far less back. The same is true at the other end: some runners simply do not respond, and there is no way to know which group you are in except by running in them.

Gait matters too. The shoes appear to punish overstriding and low cadence specifically, which is a description of most triathletes at kilometre eighteen of a half distance run.

And they wear out in a way ordinary shoes do not. The foam that produces the effect degrades faster than a conventional midsole, and a pair used as daily trainers will be mechanically finished long before the upper looks tired. You will be running in a shoe that has lost the property you paid for while keeping the geometry that loads your Achilles. That is the worst of both, and it is the predictable end point of training in them every day.

The Challenge

Look at your last month of running and work out what proportion of it was in plated shoes.

If it is more than one run in five, you are not using a racing shoe. You are training in one, and you are quietly borrowing against your calves.

Put them back in the box until your next hard session, and go and buy a boring pair.