Distance running times improved sharply once shoes combining a rigid plate with a highly resilient midsole became widely available. The mechanism is a measurable reduction in energy cost.
Running economy is the variable being changed
At a given speed, a runner consumes oxygen at a certain rate, and that rate is the practical measure of how efficiently they run.
Two runners with identical aerobic capacity will perform differently if one uses less energy per stride, and small differences compound across a long race.
Footwear affects this because each stride involves energy being absorbed by the foot, shoe and ground, and some of that energy is never returned.
Foam resilience determines what comes back
Conventional midsole materials compress on landing and return only part of the stored energy, dissipating the rest as heat.
The newer foams return a substantially higher proportion while remaining light, which means a thicker sole can be used without a weight penalty.
Thickness matters because a deeper layer of resilient material can store and return more energy per stride than a thin one.
The plate changes how the foot works
A stiff plate embedded in the midsole reduces how much the toe joints bend during push-off, lowering the work required from muscles in the foot and calf.
It also acts as a lever, altering the timing of force application so the shoe's foam is compressed and released in a more useful sequence.
Plate and foam are complementary rather than independent, and a plate in a conventional midsole produces far less benefit than the combination does.
The benefit varies between runners
Testing consistently shows a range of individual responses, with some runners gaining considerably more than others from identical footwear.
Differences in foot strike, mass, stride length and the natural stiffness of a runner's own tendons all interact with what the shoe provides.
This is why athletes still test extensively rather than assuming the newest model suits them, and why some elite runners have retained older designs.
Rules now define the boundaries
Governing bodies responded by limiting sole thickness and the number of plates permitted, and by requiring that shoes be available to buy rather than made for one athlete.
The intention was to keep competition between athletes rather than between manufacturers, while accepting that footwear technology would continue to develop.
The effect on the sport below elite level has been slower, since the shoes are expensive and wear out quickly, so club runners face a genuine cost calculation.
