Calculadora de Umbral Anaeróbico
¿Conoces esa sensación? Aceleras, tu corazón se dispara, tus piernas arden y, de repente, imposible mantener el ritmo durante más de unos minutos. Eso es el ejercicio anaeróbico: el momento en que tu cuerpo cambia a una zona de esfuerzo intenso, sin suficiente oxígeno para mantener la producción de energía. Un fenómeno fascinante que explica por qué a veces "explotamos" durante una carrera.
Calculadora: ¿en qué zona estás?
Introduce tus datos para determinar si estás en zona aeróbica, en el umbral o en zona anaeróbica.
Los dos sistemas energéticos del corredor
Para producir la energía necesaria para la contracción muscular, nuestro cuerpo tiene dos vías metabólicas principales, que activa según la intensidad del esfuerzo.
El sistema aeróbico
Este es el modo económico. En presencia de oxígeno, las células musculares transforman eficientemente los carbohidratos y las grasas en energía. Este proceso te permite mantener el esfuerzo durante horas: es el que domina durante un trote fácil o un maratón bien dosificado. La comodidad es clave, puedes hablar mientras corres.
El sistema anaeróbico
Cuando la intensidad aumenta, el oxígeno ya no es suficiente. El cuerpo entonces cambia a modo "emergencia": produce energía sin oxígeno, mucho más rápido pero por un tiempo muy limitado. Es el combustible para sprints, intervalos intensos y subidas empinadas. La desventaja: el ácido láctico se acumula, causando esa famosa sensación de ardor.
En realidad, estos dos sistemas no se excluyen mutuamente: siempre trabajan juntos, pero en proporciones variables según el esfuerzo.
El umbral anaeróbico: esa frontera invisible
También se llama umbral de lactato. Es el punto de inflexion donde la producción de ácido láctico supera la capacidad del cuerpo para eliminarlo. Cruzar esta línea roja significa comprometerse en un esfuerzo que solo puedes mantener durante unos minutos.
¿Cómo localizarlo?
Varios marcadores ayudan a identificar este umbral:
- Frecuencia cardíaca: alrededor del 85-90% de tu máximo
- En términos de ritmo: equivalente a tu velocidad de 10k para un corredor intermedio, o tu ritmo de medio maratón si estás muy entrenado
- La prueba de hablar: imposible mantener una conversación, la respiración se vuelve laboriosa
- Sensaciones: las piernas comienzan a arder seriamente, el esfuerzo se vuelve claramente incómodo
Más allá de este umbral, la intensidad es tal que generalmente no puedes mantenerla más de 2 a 10 minutos según el nivel de entrenamiento.
The physiological cascade of intense effort
When you gradually accelerate, your body goes through different phases. Here's what happens inside:
Balance phase
Oxygen supply meets the needs. Muscles produce energy cleanly, metabolic waste is eliminated as it goes. You can maintain this pace for a long time.
Transition phase
Intensity increases, oxygen demand exceeds supply. The body starts to draw more on the anaerobic system. It's still sustainable, but discomfort appears.
Anaerobic switch
Lactic acid accumulates rapidly in the muscles. Muscle fibers struggle to contract efficiently, the burning sensation sets in, breathing becomes short. The countdown has started: you'll soon have to slow down.
The three intensity zones
Sustainable effort, efficient energy production, maximum endurance
Fragile balance, at the limit of bearable, effort of 30 to 60 minutes maximum
Explosive but brief effort, rapid lactate accumulation, duration limited to a few minutes
Energy distribution by intensity
The harder you push, the more the anaerobic share increases. This graph illustrates this progressive shift between the two systems:
Why train in anaerobic zone?
It burns, it's unpleasant, so why inflict this on yourself? Because it's precisely by working at high intensity that you progress the most. Anaerobic work is an essential lever for running performance.
Develop maximum speed. Short interval sessions push your VO2max (maximum aerobic speed) upward. The higher your ceiling, the faster you can run.
Push back the threshold. Training regularly near your anaerobic threshold teaches the body to better tolerate muscle acidity and evacuate lactate more efficiently. Result: you can hold longer at high intensity.
Manage pace changes. In competition, surges, climbs or final sprints heavily solicit the anaerobic pathway. A runner trained in this zone will better handle these accelerations.
Improve general endurance. Paradoxically, working in anaerobic zone also strengthens your aerobic capacity. Your VO₂max progresses, your cardiovascular system becomes more efficient, and even your long runs benefit.
In summary: anaerobic training makes everything else easier. It's the price to pay to progress.
Muscle burn: where does it really come from?
For a long time, lactic acid was blamed as the culprit. In reality, it's more subtle. When the muscle produces lactate in large quantities, it also releases hydrogen ions (H+). These are what acidify the muscle environment.
This acidity disrupts contraction mechanisms: muscle fibers struggle to contract efficiently, nerve impulses are less well transmitted. Result: that characteristic sensation of burning legs that refuse to obey.
Lactate itself is not really a toxic waste. It can even be recycled by other muscles or by the liver to produce energy. The real problem is the rapid acidification of the muscle environment when you push too hard, too long.
Remember: lactate is an indicator of intense effort, not a poison. It's the acidity that limits performance.
When do you switch to anaerobic? Concrete situations
Anaerobic effort is not reserved for elite athletes. It occurs in many situations:
The final sprint. Whether it's over 100 meters or in the last hectometers of a 10k, any maximum acceleration massively solicits the anaerobic system.
Steep hills. Climbing a steep slope requires high muscular power, quickly limited by lactate accumulation.
Short intervals. Sessions like 30"-30" or 200m repeats at high intensity dive directly into anaerobic zone.
Starting too fast. Starting like a rabbit on a 5k when you don't have the level is a guarantee to "pay" the bill after two kilometers.
Entire races. For an amateur runner, running a 5k all out can involve a significant anaerobic portion, especially in the second half.
How to recognize you're in anaerobic zone?
Several body signals don't lie:
- Labored breathing, impossible to say more than a few words
- Intense burning sensation in the thighs
- Very high heart rate, often above 90% of maximum
- Feeling that legs become heavy, less responsive
- Certainty that you won't be able to maintain this pace for long
What to remember
Anaerobic effort begins when intensity exceeds approximately 85-90% of maximum heart rate. From this threshold, the body can no longer supply enough oxygen to the muscles, which switch to an emergency energy production mode. Lactic acid accumulates, muscle acidity rises, and the effort becomes hardly sustainable beyond a few minutes.
Uncomfortable but essential: it's by regularly working in this zone, through intervals, sprints or hills, that you push your limits. You improve your maximum speed, you raise your anaerobic threshold, you strengthen your cardiovascular system. In short, you become a better runner.
Understanding this mechanism also helps avoid classic mistakes: starting too fast, persisting at an unsustainable pace, or conversely, never leaving your comfort zone. Mastering anaerobic exercise means learning to dose effort and progress intelligently.