Fatigue, Injuries, and Adaptation in Modern Soccer: A Tactical Periodization Perspective

DAVID TENNEY

Soccer is evolving, and with it, new challenges arise for players, coaches, and sports scientists. One of the biggest issues today? The alarming increase in injuries.

But why does this happen? Is it just about playing more games, or is there something deeper going on?

One of the clearest patterns we’ve seen is how changes in competition schedules directly impact injury rates.

Take Major League Soccer (MLS), for example. In 2023, the introduction of the Leagues Cup—a tournament played alongside Mexican teams—forced a major adjustment in the season. Instead of a continuous schedule, teams took a break in July and August and had to play more midweek games earlier in the season.

The result? A 35% increase in injuries across the league.

A similar trend is seen in teams that qualify for European competitions for the first time. Whether it’s the Champions League or the Europa League, the sudden shift in schedule and intensity leads to a surge in injuries.

So, what’s really happening here?

Many assume that fatigue is just a physical issue—something that can be measured through heart rate, muscle soreness, or sprint distances.

But Tactical Periodization teaches us that the game is not just physical. It’s also mental and emotional.

Playing in the Champions League for the first time isn’t just about running more—it’s about the mental pressure, cognitive demands, and emotional toll of playing at the highest level.

Are coaches adapting their training and recovery strategies to account for this?

One of the biggest issues in sports science today is its overreliance on measurable data.

Decisions are often based only on what can be quantified—sprints, accelerations, heart rate variability. But what about the things we can’t measure?

Take Formula 1 drivers as an example. If we measured their fatigue based only on heart rate and muscle activity, we’d think they’re fine. After all, they don’t run or jump.

But mentally, they are completely exhausted after a race. The same applies to soccer players.

Fatigue isn’t just physical—it’s cognitive and emotional too.

Another common mistake is how we define intensity in soccer.

Many assume intensity is just about running faster, covering more ground, or increasing sprint counts. But in Tactical Periodization, we know true intensity comes from decision-making under pressure.

Pep Lijnders, in his book Intensity, challenges traditional sports science with a bold statement:

“Linear running is the enemy of intensity.”

Why? Because running in a straight line lacks cognitive and emotional engagement. True intensity comes from game-like scenarios, where players must think, react, and adapt instantly.

But are current training methods designed to reflect this reality?

The modern game is more demanding than ever. But simply increasing physical workload without considering the cognitive and emotional aspects of the game is a recipe for failure.

Coaches and sports scientists must embrace a more holistic view of fatigue, intensity, and recovery. Tactical Periodization provides the foundation for this, integrating all elements of performance into a single, cohesive approach.

Because in soccer, success isn’t just about how much you run—it’s about how well you think, adapt, and recover.