After playing at Qatar 2022 at age 35, US national team defender Tim Ream thought it was “pretty unlikely” he could play in another World Cup. But he decided he would at least try to stay in the game as long as possible.

“Because for me, it’s about pushing boundaries, pushing myself, pushing the limits of what I can physically and emotionally handle,” he told Al Jazeera.

Last week, Ream was named as the US’s captain for the upcoming football tournament in North America and, at 38, is the oldest ever outfield player in a US World Cup squad.

“To be given the honour and the opportunity to wear the captain’s armband in a home World Cup is incredible,” he said.

Ream, who played for Bolton Wanderers and Fulham in the Premier League and is now at Major League Soccer (MLS) side Charlotte FC, is one of several outfield players in their late 30s and beyond at the 2026 World Cup; including Portugal superstar Cristiano Ronaldo, 41, the 40-year-olds Luka Modric and Edin Dzeko, Yuto Nagatomo, 39, and Argentina legend Lionel Messi, who turns 39 later this month.

Evolving sport science plays a significant role in extending career longevity – the days when “recovery” meant having a few beers after the game are long gone, and many players now extoll all kinds of developments from lymphatic draining to cryotherapy.

Huge amounts of data measuring biomarkers from heart rate variability and muscle oxygenation to hormonal fluctuations and inflammation are also now available, including from wearable technology.

But experts argue that sport science is just part of a complex system of interlocking factors needed to extend longevity in football, including culture, relationships, a learning mindset, luck, resources, and the motivation to keep going into a fifth decade.

“It’s not just about the science, or machines, or AI,” Vlatko Vucetic, a professor of kinesiology at the University of Zagreb who has worked as a personal trainer with Croatian and Real Madrid star midfielder Modric for more than 10 years, told Al Jazeera.

“This question is always about people.”

‘I’m setting an example’

Footballers tend to peak before the age of 30, with research suggesting a general decline in the early 30s in terms of speed, power and explosiveness, although endurance fades more slowly.

As players age, recovery takes longer, and they also become more susceptible to injuries. Football has also gotten much faster and more physical over the last few decades, and the number of matches at the elite level has increased dramatically.

Goalkeepers have tended to play on the longest; the oldest World Cup player ever was Egyptian keeper Essam El Hadary, who played at Russia 2018 at the age of 45.

According to Transfermarkt.com, only 15 players aged 35 or above appeared in the Premier League this season out of more than 500 players.

However, there is evidence that the median age of footballers may be increasing, while the number of outfield players playing into their late 30s and early 40s at the upcoming World Cup is striking. Before this tournament, Cameroon’s Roger Milla – who scored at USA 1994 aged 42 – was the only outfield player in their 40s to play at a World Cup.

Ben Rosenblatt was the lead performance coach for the England men’s team for seven years and is the founder and director of 292 Performance, a sport consultancy firm that trains and advises elite individuals and organisations.

He told Al Jazeera that advances in sport science and data collection – and an increased focus on health and wellness culture inside and outside the game – have helped extend careers in football.

“Within the game, there is more attention to detail over the last two decades being placed on an understanding and knowledge around training science and in particular, how to schedule organised training sessions to optimise athletes’ performance and reduce injury risk – which is obviously going to be a big survival factor for players,” he said.

While Rosenblatt says longevity relies on “the amalgamation of all the different tools, resources, culture and behavioural shifts that are taking place within the game”, the fundamentals remain crucial; training, recovery, sleep, lifestyle, nutrition and hydration.

“It’s about doing the stuff that’s quite boring and basic 99 percent of the time,” he said.

Vucetic is an evangelist for elastic resistance bands, which he says help keep the body strong and agile by enhancing muscle plasticity, and for microdosing exercises throughout the day to stay primed for explosive demands like sprints, jumps and sudden changes in direction and prevent injury.

But he also says athletes need to excel across eight “parameters”: a healthy lifestyle, morphology (physical form and body structure), motor skills, motoric knowledge (the capacity to learn movement), energy capacity (especially aerobic and anaerobic fitness), mentality, intelligence, and socioeconomic status.

And Vucetic says maintaining motivation and love of the game is crucial to longevity, as senior players need to work harder for diminishing returns. Many older players – who may have families, a declining salary and opportunities, and a creaking, protesting body – find staying in football to be too much of a grind.

“That’s challenging, and a lot of athletes after 30-35 cannot continue with this,” he said.

Vucetic said the motivation to keep playing at an elite level as players age is usually intrinsic, rather than for money or other extrinsic factors. For Modric, it is the desire to be the “best version of himself” and an enduring love of the game.

“He likes to play like a kid in the sand, as we say in Croatia,” he said.

Ream – who made his US men’s national team debut way back in 2010 – says recovery has become harder as he’s aged and he credits Pilates, red-light therapy, and prioritising sleep with helping him in recent years.

He says the hardest part of playing on at 38 is being away from his family for large stretches. But he notes that he is partly playing on for his three children.

“[I’m] setting an example for them of setting goals and following through and pushing yourself and grit and determination and leadership,” he said.

‘It’s all about connections’

Paddy Hogben, rehab strength and conditioning coach at Premier League club Brentford FC, recently co-authored an academic paper about longevity in professional sport that highlighted the importance of “psychosocial and organisational” variables – such as a supportive environment and leadership qualities – for extending careers in football.

“I was definitely surprised by the lack of emphasis a lot of the players put on lifestyle and physical things, and that they talked more about opportunities and relationships,” he told Al Jazeera.

Hogben says that while most clubs want to extend the careers of their players, economic pressures can undermine longevity, as a 20-year-old’s resale value will be considerably higher than that of someone a decade older – so successful senior players usually provide added cultural or social value for their clubs.

“If you’ve got older players that have got good emotional intelligence, good communication abilities, can lead for you on the pitch – I think that’s where you will find a way to play them, even if you’ve got a replacement that could output more,” he said.

Hogben noted that this requires a learning mindset from early in the career and the ability to balance supreme self-belief with humility.

“If you can think you’re the best, but part of that is because of your growth mindset, your ability to evolve, to keep getting better – I think that’s such an underrated form of talent.”

Veterans playing into middle age will often adapt their game to compensate for slowing legs with assets like enhanced vision.

“I think my biggest improvement is being able to see things as they’re developing, and as they’re happening, but then also understanding and adapting to different coaches,” Ream said.

“I think that’s where you have to understand the interpersonal side with this game, because it’s all about connections, it’s all about communication, it’s all about relationships on and off the field.”

Tactics and positioning are also important for veteran players; the middle-aged Ronaldo would surely not take kindly to being asked to work the channels anymore.

“[Older players] are probably at a club where they have got some influence, they can train in a way that helps them, they can have a tactical ear with the coach to be in a role that is right for them,” Hogben said.

Looking ahead, Rosenblatt says putting the huge amount of available data together to create a more holistic picture of a player could be “transformative” for longevity.

“That’s kind of the Holy Grail, because you can give clarity to a manager or an owner game by game or across the course of a season about what the player is capable of delivering, and then obviously what development they require,” he said.

And extending longevity means establishing routines, discipline, and what works early on.

“I know so many players who, towards the end of their career, tried to find a routine and they couldn’t stick with it because they hadn’t done it early enough,” Ream said.

“Find these things and get into them early, because it’ll help you in the long run.”