Written by Teemu Virtanen

Source material by Training 4 Endurance & Wikipedia

Visma Ski Classics, being the world-class long distance pro skiing tour, is a prime example of a proper endurance sport. Our pro skiers train hard and spend long hours getting into shape. Our races usually take a long time to complete and they strain our skiers physically and mentally. But what is endurance in its essence? Let’s define the term and see what really constitutes an endurance sport. Wikipedia defines the term as such:

Endurance (also related to sufferance, resilience, constitution, fortitude and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from, and have immunity to trauma, wounds, or fatigue. It is usually used in aerobic or anaerobic exercise. The definition of 'long' varies according to the type of exertion – minutes for high intensity anaerobic exercise, hours or days for low intensity aerobic exercise. Training for endurance can reduce the ability to exert endurance strength unless an individual also undertakes resistance training to counteract this effect.

So, endurance can be defined as the ability to withstand stress over prolonged periods of time. An endurance sport is therefore any sport in which there is a prolonged physical stress. The main requirement is the ability to sustain a fast pace over a prolonged period, without sustaining undue fatigue through the build up of lactic acid.

Long events increase aerobic demand as duration increases, and the main aerobic source of energy is through the metabolism of carbohydrates (glycogen) and fats in the form of free fatty acids. Energy is also supplied from the anaerobic metabolism of glycogen to form lactate and an initial 4-6 seconds supply comes form the intra-muscular store of high-energy phosphates.

Despite being small the anaerobic contribution may make a significant contribution to the relative exercise intensity sustained during long events, particularly it comes into play when working hard up a hill, during mid race surges or during a sprint finish. However, the majority of a middle/long distance athlete’s training time would be devoted to developing and maximizing their aerobic capacity and efficiency.

An athlete’s level of ability, as an endurance athlete, will be determined by a number of key physiological components. These key components include:

• Maximal oxygen uptake (V0₂max)
• The Economy of Motion / Oxygen Economy
• The Lactate Threshold / Anaerobic Threshold
• The Velocity at V0₂max (vV0₂max)
• The Sustainable % of V0₂max
• Peak power output – Power at (V0₂max)
• Maximal Lactate Steady State
• Fractional utilization – %V0₂max at lactate threshold

When discussing about any endurance sport and training methods to enhance and improve the components mentioned above, we come across to important training terms; aerobic and anaerobic exercises. Wikipedia describes these training methods as follows:

Aerobic exercise (also known as cardio) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process. Aerobic means "relating to, involving, or requiring free oxygen", and refers to the use of oxygen to adequately meet energy demands during exercise via aerobic metabolism. 

Anaerobic exercise is a physical exercise intense enough to cause lactate to form. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass. Muscle energy systems trained using anaerobic exercise develop differently compared to aerobic exercise, leading to greater performance in short duration, high intensity activities, which last from mere seconds to up to about 2 minutes. Any activity lasting longer than about two minutes has a large aerobic metabolic component.

In our future articles, we will get into these two types of crucial exercises in more detail and find out how our pro skiers develop needed skills for going fast and long on ski tracks.