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Intensity zones: The key to your development


You’ve been training consistently, adding volume to your runs each week and eating all the right energizing foods to boost your performance. So how come you’re not showing any sign of progress and still far from hitting that 10km goal?

An effective training plan is a lot like a relationship. If everything stays the same, we get bored, don’t develop, change or adapt and therefore nothing improves. To develop, we need variety. A balance of comfort and excitement. Same goes for our training. Progress in your performance depends on the correct distribution of intensity: extremely light sessions to help you recover, light ones to improve basic endurance levels and tough, high intensity workouts to increase speed and stamina. The question is, how do we measure intensity? Since it’s not as straightforward as frequency or duration, that’s where training areas come in.

Training areas – or intensity zones – are the target ranges used to prescribe workout intensities. Were you really training hard enough and reaching your maximum capacity? Or was it too intense to allow your body to actively recover or build on its basic endurance levels? You will only be able to answer these questions correctly if you know your individual training areas. Due to the linear relationship between heart rate and training intensity, this is how training areas are defined. Your training areas are determined as a percentage of your maximum heart rate.

  • Zone 1: <70%
  • Zone 2: 65-75%
  • Zone 3: 75-85%
  • Zone 4: 85-95%
  • Zone 5: 90-100%

The first 3 are related to mainly aerobic metabolism processes below the lactate threshold, whereas the 4th and 5th zone correspond to mainly anaerobic processes at or above the threshold. Intensity zones are used in sports because training at different intensities stresses your body in different ways, leading to different physiological adaptations and resulting in different benefits.

Zone 1 is used to train the body’s ability to recover faster, as well as partly for the training of fat metabolism and is defined as the extremely light zone.

Zone 2 is the primary aerobic base building zone.This “light” zone is for long runs and any other long endurance sports where you are running or moving at a pace which allows you to hold a conversation with your training partner. It’s used for the stabilization of the performance level, technique economization as well as the training of fat metabolism and improving basic endurance levels – extremely important for all sports.

Zone 3 is the moderate zone. Although still within the aerobic range it represents a more challenging aerobic pace, although still being able to speak in full sentences with your training partner. Training within this zone is also used for the stabilization of performance level as well as the training of glycogen metabolism. This zone prepares the body for higher intensity sessions.

Zones 4 and 5 are in the anaerobic range. The intention here is lactate compensation and training of the anaerobic capacity – or in other words stamina and strength-endurance training. It is mainly interval training that falls into this category, where the workout would be described as hard or really hard.

Lactic acid & training intensity

Diagnostics can also define intensity areas by measuring the amount of lactate in the blood during exercise. Think back again to our article on lactic acid. That’s right, the “waste product” floating around your body as a result of intense exercise. Although it’s mainly to blame for fatigue, never forget that lactic acid also has it’s good qualities. It’s used to produce oxygen again and regulate the PH value. But what’s the connection between intensity and lactate you ask? With training intensity – and therefore a higher need for oxygen – lactate is used as an additional source of energy, resulting in higher lactate levels in the body, which is later measurable in the blood. If the load raises to a level where muscular lactate production is higher than the bodies oxidative capacities, you reach a point where you can no longer go on with training and have to stop.

Since we cannot test blood every time during training, by correlating lactate levels with heart rate and pace, it’s possible to gain an accurate impression of your intensity level. A fitter, more trained runner will have a higher lactate threshold than a less fit individual.