During Andre Agassi’s two decade stint in tennis, the one constant in his team was his fitness trainer Gil Reyes, the man who became the player’s rock throughout his career.
Reyes remembers an evening during his charge’s run to the 1990 French Open final when Nick Bollettieri, Agassi’s coach, was sent down the Champs Elysees to find food for the team.
“It had been a tough practice, we were going to stay in that evening and not go to a restaurant,” Reyes told Al Jazeera as he recalled that day.
“After getting everybody’s order, Nick ended up spending $200 at McDonalds feeding the troops.”
While the 20-year-old Agassi had a certain weakness for hamburgers and fries on tour, his dietary inclinations were far from unusual.
At the time, it was the perceived wisdom that fast food and fizzy drinks were not a problem for athletes. Few raised an eyebrow when Boris Becker sipped Coca-Cola at the change of ends.
It gave them vital energy they needed to get through the intense training and matches and they would burn it all off the next day anyway.
Bjorn Borg swore by the benefits of steak as he amassed six French Open titles.
“These days you see players travelling with a coach, a physio or fitness coach, and some even have their own travelling nutritionist or chef,” Reyes added.
“That certainly wasn’t the case when Agassi and I started out. In those days, your nutritionist was whoever had the phone number for the nearest Pizza Hut.”
In the mid 1990s, Agassi and Reyes were among the first to start looking at the impact proper nutrition could have on a player’s performance. But it’s only been in the last decade that players have begun to regularly tinker with their diets in search of the edge.
“We’ve maxed out the technology, the rackets, the strings, even the clothes and shoes which have all transformed the sport in the last 15 years.
“Everything is so technologically advanced, it just leaves us with the ultimate arsenal which is the body. And in the quest for greater performance, everyone’s asking themselves a lot of questions.
“I tried it for a while but it isn’t easy.
“There are a lot of constraints and I didn’t notice a huge amount of difference for me.
“However, not eating gluten does force you to eat healthier foods.
“You really have to think hard about what you choose – more vegetables, less bread and pasta.”
“Unfortunately, the culture of sport can be quite anecdotal and it can untether itself from fact or science Those of us on the inside can find ourselves being swept up in the tide of culture.”
Reyes was referring to the gluten-free and low carbohydrate lifestyles which have swept through the tennis world in almost-viral fashion over the past four years.
This was propelled by social media and locker room whisperings.
Mardy Fish was the first elite player to credit cutting down on carbohydrate with on-court success.
Plagued by joint injuries, Fish lost several stones on an Atkins style low-carb diet and reached a career-best ranking of seventh in 2011.
But it has been the extraordinary exploits of Novak Djokovic, who went 42 matches unbeaten that same year (2014 win streak is 27), which forced the topic of gluten into the wider consciousness.
“Everyone’s aware because of one amazing athlete who’s made it internationally popular to give up gluten.”
It is often forgotten that Djokovic and Sabine Lisicki were driven to go gluten-free because they have celiac disease, according to Reyes, meaning they are clinically allergic to gluten.
Djokovic has recently launched his own range of gluten-free products. Grigor Dimitrov currently follows a gluten-free diet. Andy Murray experimented with it along with Jo-Wilfried Tsonga and Tomas Berdych.
However, like many male players, Murray became concerned that losing weight on the diet would lead to a loss of power.
Reyes is wary of the one-size-fits-all approach, cautioning that diet is a highly individual thing which depends on a range of variables including age, body type and natural agility.
“Everyone, female players in particular, is finding it tough to walk away the trends of giving up carbs. It might suit some but I’m not sure whether many athletes know clinically whether they should or shouldn’t.”
Reyes has spoken to nutrition experts at Harvard University and Columbia University who say that 55-70% of our everyday food intake should be carbohydrate.
“That’s just for normal people, let alone athletes who spend their time training and competing. I encourage my athletes to first get blood tests and find if they’re actually allergic to gluten.”
But while gluten has sparked an increased interest in nutrition, it isn’t the only source of dietary curiosity.
It’s harder for the lower-ranked players though. The cost of dinner from a fast food chain is usually much less than a healthier option
World number 122 Denis Kudla went vegan for two months.
Eugenie Bouchard and Victoria Azarenka have been investigating so-called superfoods such as the acai berry and maca, a root vegetable which grows in the Andes mountains of Peru and is thought to aid stamina and recovery.
“There’s more awareness now about putting proper energy in the body, getting the right amount of protein your body needs and every little thing that can help you function even one percent better,” Bouchard’s coach Sam Sumyk said.
“It can be difficult on the road but we always try to eat local products, whatever country we’re in. If you want to be the best you can be, you have to look at what you eat.”
France’s Benoit Paire still admits to often indulging in a pre-match pizza or cheeseburger, but these days he’s among the exceptions on tour.
“I think we all realise now that diet can make a big difference,” Tim Smyczek said.
“All the top guys are going to great lengths to find minute advantages to set themselves apart and I think diet is a small part of a larger culture of professionalism that is different at the higher levels of the game.
“It’s harder for the lower-ranked players though. The cost of dinner from a fast food chain is usually much less than a healthier option.”