Before the world No. 21 ranking, the three ATP titles, the Davis Cup final and the run to the Dubai final this year, Tallon Griekspoor spent years on the Challenger circuit — where he won eight titles in a single season, a record. He has been the Netherlands' No. 1 ever since.

We had the pleasure to ask him about optimising recovery and performance.

At your level everyone trains hard. Where does the actual difference come from?

Everyone in the top hundred can hit the ball. That's not what separates anyone. If you put us all on a court fresh, rested, at home, the gap between number twenty and number ninety is very small. The gap opens somewhere else entirely.

It's the sixth week of a swing. You've flown three times, you've slept in four beds, you lost in the first round somewhere and flew out that same night. Now you have to play a guy who's been at home for two weeks, and the question isn't who trains harder. It's who actually arrived. Whether my body is available when I need it — that's the thing I have most control over, and it's the thing most people spend the least time on.

Tennis has no off-season, which people underestimate. There's no eight weeks in the summer where you rebuild. So everything I do has to survive being done in a hotel room in a city I don't know, in a week where nothing is going well. If it only works when I'm at home and everything is calm, it's not a system, it's a holiday.

There's an endless amount of trends and protocols in sport now. How deep into that world are you?

I try most things. I'm curious and I'll test almost anything once, so my answer is probably deeper than it should be. But what I've ended up keeping is very simple, and it's all built on the same idea, which is how the body is actually meant to work.

We're built to move on uneven ground, be in daylight, be hot and cold sometimes, sleep when it's dark, eat real food. Modern life removes basically all of that. And my job removes it even more than a normal life does — I'm indoors, on planes, in air conditioning, under artificial light at eleven at night, on hard flat surfaces in shoes with a lot of structure. So a lot of what I do isn't really adding anything. It's putting back what the environment took out.

That's why I use barefoot shoes in the gym. Not because it's a trend but because feet are the foundation of the body. Same with sauna and cold, same with getting sunlight in the first hour of the day, same with infrared. The supplements I take are there to optimise the last percent of performance and recovery. And these last percent matters. None of it is exotic when you look at it that way. It's just old things, done deliberately, because they don't happen by themselves anymore.

How do you decide whether something earns a place in your routine?

Two tests. First one is whether it still works when everything is bad. Anything I can do at home in a calm week is easy. Can I do it in Melbourne / a hotel with no gym / after a night flight? If it needs perfect conditions, it doesn't count, because the weeks I need it most are the worst ones.

Second is whether it needs too much willpower. That took me longer to learn. If something requires me to convince myself every night, I'll do it for three weeks and stop. I have a limited amount of discipline and I want to spend it on the court, not on hundreds of routines. So the things that survive are the ones that are basically automatic. Almost like a button I press.

I've dropped a lot of things over the years, and not because they didn't work — some of them probably did. They just didn't survive contact with a real season. That's a different standard than whether something is effective in theory.

Most of what you do isn't really made to be seen. Does that matter to you?

Honestly it's part of why it works. There's no audience for any of it, so there's no performing. The training you can post. The rest of it happens alone in a room, and it looks completely ridiculous — I'm not going to pretend otherwise. Half of what I do, people will never see.

But I've thought about this more than you'd expect, because most things you can only do alone are things you skip. If it needs privacy, then it needs a private room, time, nobody around — and on the road I don't always have that. So the ones I actually keep are the ones I can do anywhere.

That's the honest reason I wear HEVO. They're the only part of my evening routine I can do with other people in the room. Team dinner, players' lounge, the flight, sitting with my girlfriend watching something — I put them on and nobody looks twice, and I get the benefit anyway. Everything else in my evening requires me to be alone. That one doesn't, and because of that it's the one I never miss.

None of this is the interesting part of being a tennis player. Nobody watches a match and thinks about what I did at nine the night before. But the difference between me at my best and me at seventy percent isn't visible either, and they're the same thing.