What factors does sports performance depend on? (Series 1: Energy systems)

My friends at 42K have challenged me to periodically produce content about endurance race training, applicable to all levels.

The idea for this section is clear: through short texts —which we’ll call series— we’ll address practical applications of endurance runner training based on my professional experience, without leaving aside the academic rigor that inevitably stays with me.

I don’t intend to discover a magic potion or any secret formula regarding sports performance. In many cases, what you read will reinforce what you’re already doing. In others, it might help you introduce adjustments that make your sessions more efficient. It’s also not about questioning the work of other professionals: sports performance can be achieved through different paths. I’ll talk about what I understand works for me.

While I receive suggestions on specific topics -I encourage you to send them in the comments-, I’ll start by answering a fundamental question:

What factors does sports performance depend on?

We could find multiple answers, approaches, and nuances when addressing the question of what factors sports performance depends on. However, from my point of view, success in sports training is mainly based on two major pillars:

• The race profile
• The athlete’s profile

In this first series, we’ll focus on the former.

Series 1: Energy System Contributions

The race determines the physiological demands

If we’re talking about improving our sports performance at a specific distance, it’s clear that the needs of a 5K aren’t the same as those of a marathon.

Physiological demands fundamentally depend on one factor: the duration of the effort.

To the point that, in terms of energy metabolism, a cyclist looking to break the hour record will use similar metabolic pathways to those of a half-marathon specialist, as both efforts last around 60 minutes.

In other words, different disciplines can share similar energy requirements if the effort time is comparable.

What energy systems are and why they matter

If you search for the term “energy system contributions” you’ll find plenty of scientific literature analyzing how different energy systems contribute depending on the duration and intensity of the exercise. That’s what I did back in the day to develop the theoretical framework for my doctoral thesis.

To put it simply, our body has three major energy production systems:

• Alactic anaerobic system (very short and explosive efforts)
• Lactic anaerobic system (high intensity, short-medium duration)
• Aerobic system (prolonged efforts)

In endurance races, the aerobic system plays a clear leading role. However, the other systems don’t disappear: they contribute at specific moments like changes of pace, short climbs, or final sprints.

The fuel tank analogy

We can imagine the body as a vehicle with several fuel tanks.

Training seeks to optimize:

• The capacity of each tank.
• The efficiency with which we use each one.
• The transition between them.
• Fatigue resistance when the dominant system starts to run out.

If we use all the “tanks” at maximum intensity from the start, we’ll only be able to sustain that effort for a limited period. Afterward, fatigue will appear prematurely and performance will drop. Therefore, that strategy only makes sense for short-duration endurance races (middle-distance).

On the other hand, if we properly manage which energy system predominates at each moment, we can sustain performance for longer.

The route also modifies energy demands

In long-duration road races, we usually look for flat routes to optimize the final time. But why does this happen?

A flat route allows for a more stable intensity, which favors greater efficiency of the aerobic system.

In contrast, in trail running or cross-country races:

• Uphill sections increase anaerobic demand.
• Downhill sections modify the muscular pattern and energy cost.
• Constant variations alter metabolic stability.

This implies that, even while maintaining the same total duration, the relative contribution of energy systems changes according to the terrain.

Duration + route profile = strategy

When we combine:

• Duration of effort
• Intensity
• Terrain profile

An essential concept in endurance performance appears:

Pacing (rhythm distribution)

Pacing isn’t just “starting slower”; it’s the ability to strategically distribute effort to:

• Optimize the use of energy systems.
• Delay the onset of fatigue.
• Maximize final performance.

We could say that poor pacing involves prematurely activating less efficient energy systems for prolonged efforts.

Good pacing means understanding what the race requires and adapting the energy strategy from the very first kilometer.

In the next series, we’ll address this concept in depth and connect it with energy contribution systems.

Conclusion: understand before intervening

Sports performance doesn’t just depend on training more or training harder.

In reality, it depends on understanding the following:

• What the race requires.
• Which energy systems predominate.
• How the duration of the effort influences it.
• How the terrain modifies physiological demand.

Ultimately, training with intention implies understanding the energy context of the effort.

If you’re interested in diving deeper into the factors that determine sports performance, I’ll see you in the next series.

“Running is easy; training with intention is another story.”

Comments

Be the first to comment on this post!

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Comment *

Name *

Email *

Website

¡No soy un robot! *Captcha loading...