This article introduces The Athletic’s World Cup performance series, in which Alan McCall draws on more than 20 years of experience across elite football to explain the science behind the challenges teams are facing this summer and the strategies they will use to deal with them.He begins unpacking the unique challenges of preparing for a World Cup that spans three countries and a dizzying range of conditions.The 2026 World Cup will expose teams to an unusually complex mix of environmental and logistical challenges across three countries, multiple climates, vast travel distances, and potentially differing altitudes and time zones — not because these challenges are new to World Cups, but because they may be more pronounced and variable across a single tournament than ever.Environmental and logistical challenges are part of international tournament football. Teams have long been required to adapt to demanding and often unpredictable conditions, from altitude in Mexico in 1986 to the heat of the United States in 1994 to travel across countries in South Korea and Japan in 2002.More recently, Russia in 2018 brought extensive travel distances but generally moderate and relatively consistent environmental conditions, while Qatar in 2022 presented a different type of challenge — a World Cup played during the middle of the club season for many of the world’s elite players, but with minimal travel between venues and climate-regulated stadiums.These were significant demands, but they were often more stable, predictable, or centred on one primary factor, allowing teams to prepare more specifically.The demands of 2026, however, cannot be so easily separated. The challenge at this summer’s World Cup lies in the cumulative effect of transitioning between environments across matches, and the variability this creates for preparation, recovery, and performance.Fluminense players trying to cool off during the Club World Cup at the New York/New Jersey stadium last summer (Paul Ellis/AFP via Getty Images)Across a World Cup, these performance influencing pressures accumulate. Match play naturally induces fatigue and can disrupt sleep. Travel compounds this, particularly when combined with changes in climate, altitude, and routine. Heat and humidity likely further impair recovery, while altitude adds an additional physiological strain. These factors do not act alone — they interact and influence physical recovery, mental freshness, and decision-making across the tournament.Throughout this World Cup Performance series, I will draw on more than 20 years of experience across club and international elite football, alongside conversations with elite players, medical and performance staff, and leading researchers, to explore how teams are likely approaching these challenges and the science and practical realities shaping those strategies.Better prepared than everWhile the 2026 World Cup may present a uniquely complex combination of challenges, the effects of these demands are now better understood. The science is stronger, monitoring technologies are more advanced, and many medical and performance staff possess greater exposure to elite competitions and major tournaments than at any previous World Cup. This gives teams a better opportunity to prepare with greater precision for the combined physiological, mental and logistical demands of heat, travel and altitude.The most effective application of these approaches tends to come from experienced and integrated medical and performance teams — including doctors, physiotherapists, physical performance coaches, sport scientists, and nutritionists — who understand not only what to implement, but when and how to apply it within the realities of tournament football.Over time, these staff groups develop an ability to recognise patterns, anticipate challenges, and distinguish what matters from what does not. When that learning compounds across multiple tournaments, it can become a significant competitive advantage.Les Gelis, who worked across multiple World Cups with Australia’s men’s team, captures this well: “Having core staff across two, three or four tournaments creates a form of organisational maturity. The key is being able to cut through the noise and become more efficient.”Countries such as Germany, Argentina and Croatia may not approach preparation in exactly the same way, but there is often an underlying organisational DNA shaped through repeated exposure to major tournaments and challenging environments. Croatia, finalists in 2018 and third-place finishers in 2022, have become one of international football’s most consistently competitive tournament teams.Former Croatia national team doctor Zoran Bahtijarevic, who worked across four World Cups, described how that accumulated tournament experience can shape future preparation. “You use your own learning over time and tournaments as well as your own research and you improve each time,” he said.No perfect plan, only probabilities – and trade-offsThere is no perfect plan for preparing for the 2026 World Cup. For many teams, preparation begins years in advance — often before qualification has even been secured — before becoming progressively more specific once opponents, host cities, and potential routes through the tournament are known.