Judo and badminton might not be the first two sports that one thinks of when working out how to build a footballer but perhaps that shows a lack of imagination. There were those at Ajax who saw it differently. Manchester United's Donny van de Beek is among a generation of talent who have benefited from the innovative ideas of Dutch coach Rene Wormhoudt.
It was Wormhoudt who developed the Athletic Skills Model adopted by Ajax in the first part of the last decade. The principle was that youngsters needed to compete in other disciplines to become the best athletes that they could be. Racket sports were incorporated into the programme and, yes, even a dojo built so that these budding starts could go toe to toe.
As Wormhoudt explains, it was centred on one simple idea.
"Only focusing on football might not be the best way to become a football player."
Now working as a strength and conditioning coach for the Netherlands national team, Wormhoudt still has the opportunity to work with some of the players who came through the Ajax academy after his ideas were embraced. Van de Beek, now 23, was among them.
"I spoke with Donny about this when I knew we were going to talk," Wormhoudt tells Sky Sports via a video call from his Netherlands home. "He would never have been involved with judo or badminton if we hadn't implemented it in the educational programme at that time."
But how has it helped him?
"The badminton for a football player is very good for the agility, the footwork, the quickness, but it is also very useful for the hand-eye coordination, spatial awareness and rotations. If you cannot rotate on both sides at the top level you notice it and you are gone, more or less. We trained a lot with him on his left and right hand, his left and right foot."
So far, so sensible. But judo?
"I grew up with judo and martial arts," Wormhoudt explains. "What I realised is that if you could fall well, if you could have a better balance as well as the skills, you could become a better football player.
"Judo makes you very aware of the fall and when you are not afraid of the floor you make different decisions in your balance strategy. Zlatan Ibrahimovic did martial arts and he was not afraid to fall. Some guys who played outside and did volleyball or were goalkeepers, they learned not to be afraid, but most players do not know how to fall properly.
"What I learned from doing judo is that even if someone is stronger than me, I can decide which way we go. I can use your strength to my advantage. In that way, if I am totally comfortable in my balance I can use it to my advantage when you push me.
"Another benefit is core strength. This is important to performance and injury prevention. Judo also has a completely different culture to football. It all brings you something that you can use on the field. You can excel more because you are exposed to different ideas."
Wormhoudt has become accustomed to resistance - not least from fellow coaches. While he once had the support of Louis van Gaal and other influential figures at Ajax, it is a club familiar with schisms, where the battlefield of ideas can be a bloody one. They have since moved away from a programme that saw as much as half the time spent on other sports.
Parents too have questioned his methods.
"A lot of parents think that the only way to make a better player is to spend many hours on the pitch, but that is just a quantity idea. The idea that if I spend more hours on the pitch than you I am going to be better isn't right. What about quality? What am I actually doing? You still need to play football but it just a part of it. That is difficult for people to accept."
Wormhoudt understands elite sport and he is well aware that putting in the time on football details remains vital. But he is armed with the research that suggests there is a better way.
"My colleague Professor Savelsbergh showed me a study in the United Kingdom that revealed children who played three or more sports at the ages of 11 had significantly more chance of representing a national team in one of those sports. But what do we do when an 11-year-old kid is good at football? We tell them to stop playing tennis."
He tells stories of Johan Cruyff and his fascination with baseball, Marco van Basten and his rare talent with a racket in his hand. "I worked a lot with him and he is the example of what I am telling you about. At the moment, he does a lot of squash, but back in the day, he was doing a lot of other sports. He even did diving, the backwards flip and so on. It helped him.
"Ruud van Nistelrooy told me that he did taekwondo and other sports and this helped him as a striker in football."
Again, his ideas are supported by evidence.
"There is a great piece of research from Belgium that underpinned my ideas at Ajax. They found that when you trained in one sport for two hours you had a certain motoric IQ. When you trained six hours your IQ went up. Logical. But when you trained for two hours in three different sports your IQ really went up. In fact, spending two hours doing three different sports was the equivalent of six hours doing one sport. So in less time you learn quicker.
"If you want to make a better football player, you want to make a better person and that all starts with the brain. That is a much bigger field. If you are skilful that is not going to be enough at the top level. There are so many other things that you need.
"The basic movement skills like climbing and moving to music are also very important for your motor skills, adaptation, decision-making and your pattern recognition and your anticipation.
"This variety is so important. You need different experiences because it helps your adaptive ability. You can make yourself very special if you can adapt better than the other guy.
"But if you do not train your adaptive abilities, you will have worse pattern recognition, anticipation, decision-making and so on. So we need to develop the brain. You need a healthy body too but if you don't see what is happening, it is too late and it looks horrible.
"It is just a more holistic approach."
Ajax has since moved away from that approach.
"Other people came in," says Wormhoudt. "Go away with the dojo where they did the judo. Go away with the gymnastic hall. They could not get rid of the athletic skills track so it is still used for rehabilitation but it is not in the way that I had wanted or as intensely as it was.
"It is a case study now. The fact that we are still number one having spent half the time doing other sports shows the truth of that study in Belgium. You can be effective with less hours and use the rest of the time to develop your 'football' athletic ability."
Save over 25% with a NOW TV Sky Sports Pass
Catch the action for only £25 a month with this limited time offer. Watch the Premier League, Formula 1, PGA Tour and much more. Cancel any time.
Indeed, it is fascinating to think that there is now a generation of talent emerging at Ajax, including members of the squad that so wowed Europe in reaching the semi-finals of the Champions League in 2019, who were developed in line with Wormhoudt's ideas.
"I got a lot of satisfaction from that. I am very cautious about saying it is my influence. I cannot say that. It would be impossible to claim that. I will just wait for people to wake up."
In the meantime, Wormhoudt is expanding his vision far beyond elite sport. He has created the Athletic Skills Model and the Skills Garden, a solution for public spaces. In effect, these are super playgrounds designed to optimise the learning experience while making children more healthy.
"Kids used to play outside," he explains. "They would climb and they would play fight. That is gone now. So we need to fill in that development. That was my idea at Ajax.
"But the advantages of a diversified background, a background that makes it possible for you to become a footballer, also has a lot of health advantages. They can apply to anyone. Less injury. A healthier lifestyle. Less drop outs, more creativity and a longer athletic life. It is a much bigger idea."
Naturally, he has incorporated his beliefs about the need for a variety of skills to develop the all-round athlete into the Skills Garden. "I have implemented it in the design," he adds.
"I put a lot of asymmetric parts because it develops our creativity. When we were kids, we played around lampposts and cars. But when the adults came in, it all became symmetric so we lost that creativity and because we don't play outside it has a double effect.
"I am still developing and innovating. It is about building a better world."
Live EFL Cup
As for Van de Beek, he has some adapting to do for himself as he makes the adjustment to a new life in the Premier League. Fortunately, he has had some help in that respect.
"He needs to adapt quickly to a new situation and a new intensity of playing. Not only the matches but also in the training. I hear players talk about the Premier League and say that it is much more intense than the Dutch league so it will be interesting. How will he adapt? I hope that I taught him a lot about adaptation."
There is even time for one more anecdote to illustrate the point.
"It is funny," adds Wormhoudt. "I spoke to Jari Litmanen about ice-hockey training. I asked him what he learned from that. He said that he learned how to make decisions quickly, but the other thing he learned was not to get into the duels. That is a kind of adaptation.
"I hope that Donny can take that with him because he is less the man for the duels. He needs to be thinking faster and acting faster than the rest. If that is going to happen quickly then Manchester United are going to have a lot of fun with him."