Stiffness is a spring, not a virtue

Coaches have turned leg stiffness into something you accumulate, when it is really something you tune to an event.

Somewhere in the last decade stiffness stopped being a mechanical property and became a compliment. He is a stiff athlete. She needs to get stiffer. Say it in a coaching course and heads nod.

It deserves less reverence than that. Stiffness describes how much a limb deforms under a given load, and like any spring constant it is only correct relative to the job. A sprinter running at top speed with contacts under a tenth of a second needs a very stiff system, because a compliant leg cannot return energy fast enough and the ground contact stretches out. A steeplechaser landing off a barrier does not. A high jumper at planting needs enormous stiffness for a single contact and would be badly served by carrying that into their approach.

The mistake is treating it as a one-way ratchet. Train stiffness relentlessly and you get an athlete who is superb over the last sixty metres of a hundred and dreadful at accelerating, because acceleration requires the opposite: a long contact, a yielding ankle, a hip that can travel through a big range while still pushing. Those two qualities compete. You cannot maximise both in the same March.

Which is why I am sceptical of a plyometric programme that never varies its contact demand. Hurdle hops, drop jumps, pogo work, all of it delivered at the same intensity three days a week for a season. That is not building a spring, it is narrowing one. The athlete gets very good at one frequency of loading and loses the ability to be soft, and the ability to be soft is what absorbs a bad landing, an uneven surface, a slightly misjudged bend.

Ankles are the honest place to look. A stiff ankle that can also give when it needs to is the whole game, and it is not visible in any single test.

There is also a durability argument. Everything the muscle refuses to absorb goes somewhere, and in a very stiff system that somewhere is bone and tendon. The athletes I have seen accumulate shin problems were rarely weak. They were rigid, and rigid on a hard indoor surface, and doing three hundred contacts a week without anybody counting them.

Tune it. Do not stockpile it. And if an athlete cannot deliberately run soft when asked, they have lost something worth having.