Generally speaking, aerobic threshold performance is the kind of performance that can be practically maintained for hours. In this range, the athlete should feel they can continue training for a long time without feeling out of breath. In scientific terms, the aerobic threshold is the individual level of exertion at which muscle and blood lactic acid levels begin to rise above their normal levels during ascending muscle exertion. For endurance athletes, a high aerobic threshold is the key to performing longer and longer.

During aerobic metabolism, the body produces energy by burning carbohydrates and fat under the influence of inhaled oxygen and produces carbon dioxide and water as by-products (respiration and sweating). Most of our daily activities are fueled by aerobic metabolism.

The anaerobic threshold, in turn, is the highest rate or rate at which the body’s lactate intake and removal are in balance. At this threshold, the body switches from aerobic to anaerobic metabolism. Anaerobic metabolism is triggered when the intensity of exercise increases significantly, and the aerobic system can no longer keep up with the body’s energy needs. 

During anaerobic metabolism, the body burns stored sugars to provide more energy and lactic acid is produced faster than it can be metabolized. Muscle pain, burning, and fatigue make it difficult to maintain anaerobic energy expenditure for more than a few minutes.

According to Maastohiihto.com, the anaerobic threshold can be trained with various interval and intensity exercises, while the aerobic threshold must be trained with prolonged low-intensity exercises. Suppose these thresholds and the associated training are considered from the point of view of long-distance skiing. In that case, it is helpful to highlight three main training categories: interval (power) training, speed play training, and aerobic and anaerobic training.

Interval training 

This form of exercise uses a variety of work and rest periods to temporarily allow the body to exceed the lactate threshold at high intensity and then recover (lower blood lactate levels). 

This type of training uses the ATP-PC and lactic acid system during exercise, providing the most energy for short bursts of high-intensity activity followed by a recovery period. Interval training can consist of a wide range of exercises and should closely mimic sport-specific movements such as skiing.

Speed play

Speed play is called fartlek in Swedish and often in English and is very close to interval training. The main difference is the structure of the exercise. This type of training combines continuous (usually aerobic) and interval (usually anaerobic) training, including steady variations in pace and intensity during the exercise. Pace interval training is, therefore, well suited to young and active recreational skiers for whom the actual interval exercise may be too challenging or uncomfortable. 

Aerobic and anaerobic training 

Building aerobic fitness requires a lot of prolonged low-intensity exercise. Similarly, you need to do hard intervals at or near your maximum speed to increase anaerobic capacity. It is essential to understand the difference between lactate threshold and lactic acid. 

Aerobic exercise does not help with lactic acid tolerance but increases the lactate threshold. The body develops a better tolerance to the effects of lactic acid over time during practice. Anaerobic exercise improves muscle alkaline stores, allowing muscles to function with increased lactic acid. Training at or slightly above this level enhances the athlete’s lactate threshold.

Read More: Scientific discussion about lactate and lactic acid.

In addition to the above, it is worth mentioning speed endurance training, i.e., training between the aerobic and anaerobic thresholds, which is extremely important in skiing, especially long-distance skiing. Maximal endurance is the training of power over anaerobic endurance. In future articles, we will look at these exercises in more detail.

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