Marginal Gains

The office is a converted equipment store with no window, and there is a whiteboard covering most of one wall on which somebody has drawn a graph, erased it, and drawn a different one over the ghost of the first.

Dr Ellen Vasquez has been a performance physiologist for nineteen years — two Olympic cycles with a national swimming programme, then endurance running, now a professional cycling team. She is, by her own description, in the business of finding tenths.

You get asked about marginal gains constantly. Are you sick of it?

"Slightly. Mostly because people have the story backwards."

Go on.

"The idea is that you improve a hundred things by one per cent each and the compounding gets you somewhere. It's a genuinely useful management philosophy and it's a terrible description of what actually happened in the programmes people cite. Those teams also got a large increase in funding, recruited from a much bigger talent pool, hired better coaches and had athletes who'd have been world class anywhere. Then they optimised the pillows on the team bus, and the pillows got written up."

So the pillows didn't matter?

"The pillows mattered a bit. They mattered roughly as much as pillows matter. What I object to is the implication that everyone else was ignoring the big stuff and these people won by being clever about the small stuff. Almost always it's the reverse: they got the big stuff right first, which is unglamorous and expensive, and then the small stuff was worth talking about because there was nothing left to fix."

What is the big stuff?

"Sleep. Consistent training load over years without interruption. Not being injured. Eating enough — which sounds trivial and is the single most common problem I see, particularly in endurance sport, particularly in women. Those four account for most of the variance I can influence. Everything I do with a lactate meter is downstream of whether the athlete slept."

Sleep gets talked about a lot now.

"And it's still underrated, which is remarkable. If I could give an athlete one intervention and nothing else, I'd extend their sleep by an hour a night and I'd take that over anything in a bottle. The effect sizes in the literature on reaction time, on error rates, on injury risk with chronic restriction — they dwarf almost every supplement ever marketed. It's free, and nobody can sell it to you, which I suspect is related."

What about things that do come in a bottle?

"Very short list. Caffeine, which is well established and which most people mistime — they take it too late and wreck the sleep we just talked about. Bicarbonate, for events in a specific duration window, at a dose that gives a meaningful proportion of athletes serious digestive problems, so it has to be trialled well before competition. Creatine, for power events. Nitrate, modest effect, more so in less-trained people. Beyond those, if somebody shows me a supplement, my first question is what it's contaminated with, because the testing on that market is not what people assume."

Talk about the shoes.

She laughs, and then stops laughing.

"The shoes are interesting because they're the honest version of marginal gains, and the honesty is uncomfortable. A curved carbon plate in a thick compliant foam improves running economy by around four per cent for many runners. Four per cent in this sport is not marginal. That's a bigger effect than any training intervention I can deliver in a year, and it arrived in a box."

Is that a problem?

"It's a problem for comparing across eras, and the governing bodies responded the way governing bodies do — with a rule about stack height and how many plates you can have. Which is fine. But it exposed something people prefer not to look at, which is that the equipment was always doing work. Track surfaces, pole vault poles, swimsuits, bicycle frames — it's the same story every time. We only notice when a change happens fast enough to see."

Where do you spend most of your actual working hours?

"Trying to stop people getting hurt. Which is deeply unsexy and it's where the returns are."

Give me an example.

"Hamstring injuries in field sport. There's an eccentric strength exercise — you kneel, a partner holds your ankles, you lower yourself forward as slowly as you can resist. It's miserable. You can barely walk the next day when you start. The trial evidence for it is about as strong as evidence gets in this field: adherent programmes cut hamstring injury rates by something in the region of half."

And everyone does it?

"Almost nobody does it properly. Surveys of professional clubs find a large majority either don't run it or abandon it mid-season. Because it hurts, because players complain, because the coach wants the time for something with a ball in it, and because the benefit is invisible — you don't get credit for injuries that didn't happen."

That sounds like the whole job.

"That is the whole job. Prevention is invisible by construction. If I'm doing it well, the season looks boring."

What's the most overrated thing in your field?

"Data volume. Every athlete I work with generates more numbers per day than I can look at. Power, heart rate variability, sleep staging from a wrist device that's guessing, subjective wellness scores, GPS load. And there's enormous pressure to act on all of it, when most of it is noise around a signal I could have got from three questions and a conversation. I've watched athletes become anxious about their recovery score, sleep badly because of the anxiety, and then get a worse score the next morning, which confirms it."

And the most underrated?

She thinks about this for a while.

"Belief. And I want to be careful, because that's how people justify selling nonsense. But the placebo effect in performance is real, it's measurable, and it's sometimes large. Athletes told they've received a performance aid go faster. If an athlete has a ritual — a warm-up sequence, a piece of kit, a particular routine the night before — my job is not to explain that it's physiologically meaningless. My job is to make sure it's not harmful, and then leave it alone."

Isn't that a bit unscientific?

"It's extremely scientific. The effect is in the literature. What's unscientific is pretending humans are engines and the only inputs that count are the ones I can measure with a mask on their face. I've had athletes lose a season because a coach optimised their training perfectly and made them miserable doing it."

She turns to the whiteboard, where the two graphs are still overlapping.

"Physiology tells you the ceiling. Almost nobody is anywhere near their ceiling. What's actually stopping them is whether they can keep doing this, consistently, for eight more years, without breaking or hating it — and there isn't a test for that. There's just knowing the person."