Endurance training – what to do when your fitness levels drop?

What is endurance and how is it measured?

In everyday language, terms such as “fitness”, “endurance”, and “stamina” are often used interchangeably. They usually refer to overall physical condition, training level, and the ability to sustain prolonged effort. In reality, however, their meanings differ:

• Fitness is the overall, current state of the body, resulting from nutrition, training, and self-care, and can be influenced by external factors.
• Endurance means the body’s potential to perform physical activity without significantly disrupting homeostasis – in other words, without noticeable fatigue.
• Stamina refers to the extent to which endurance is utilised, depending on mental traits such as willpower or resistance to pain and fatigue. This is the ability to maintain a given level of effort despite the circumstances.

Endurance relates mainly to the body’s physiological parameters. The most popular and commonly used indicator in endurance measurement is VO₂max, also known as the maximal oxygen uptake – the maximum amount of oxygen absorbed per unit of time (expressed in litres per minute). That’s why the term cardiorespiratory endurance often appears, highlighting the role of the lungs, heart, circulatory system, and the mitochondria in the cells responsible for the breathing process. In endurance sports, VO₂max is often calculated per kilogram of body weight to more precisely determine an athlete’s endurance potential.

Other endurance indicators include:

• Anaerobic (lactate) threshold – the level of exercise intensity at which there is a rapid increase in anaerobic processes in the muscles and lactate accumulation in the blood.
• Metabolic equivalent (MET) – an exercise indicator expressed as a multiple of the standard oxygen consumption at rest, i.e., 3.5 ml / min / kg of body weight.
• Total haemoglobin mass (tHb) – indicates the extent to which the body compensates for increased effort by transporting oxygenated blood to muscle tissue.

A sedentary lifestyle and a drop in endurance

Your body’s endurance levels depend primarily on the efficiency of the respiratory and cardiovascular systems. It’s no surprise, then, that they are directly linked to your level of physical activity. Anyone who moves regularly is less likely to complain about shortness of breath, muscle soreness, or other symptoms of fatigue. On the other hand, people who avoid physical activity will notice the consequences relatively quickly, and in the long term face a higher risk of serious health problems.

The seated position is not natural for humans. Evolution has equipped us with the ability to move upright and with a musculoskeletal system adapted to daily mobility. A forced seated posture not only leads to back and musculoskeletal discomfort but also has a direct impact on endurance. If your daily routine is reduced to sitting (with occasional breaks for lying down), it can lead to:

• Weakened heart function – this applies to all cardiac parameters, but for endurance, cardiac output and stroke volume are the most important.
• Reduced vital capacity – sitting decreases chest mobility, stiffens the spine, and weakens the intercostal muscles, while the number of alveoli also drops, limiting gas exchange.
• Circulatory system impairment – changes linked to cardiovascular issues increase blood pressure but at the same time reduce the amount of oxygen that can be effectively delivered to tissues.
• Muscle weakening and atrophy – physical inactivity leads to the loss of muscle tissue and a decrease in the number of mitochondria in muscle cells, impairing the process of cellular respiration.

The effects of inactivity can be felt in everyday situations – a broken lift, carrying shopping bags upstairs, or a brisk walk to catch the bus. In theory, nothing too demanding, but within moments your breathing becomes short and shallow, your pulse races, you feel a “burning” sensation in your lungs, and your muscles ache for a while afterwards. In the long term, a decline in endurance means reduced mobility and independence – and ultimately, a higher risk of heart and respiratory diseases.

If you recognise the symptoms described above, the message is clear – it’s high time to start regular endurance training.

Activities that build endurance

According to the report “MultiSport Index 2024: Sportcrastination”, as many as 34% of Poles do not exercise at all. One of the reasons for this is the way we perceive sport – it often appears to us as something difficult, competitive, requiring sacrifice, and leading to injuries. Many of us think the same about endurance training. We picture long-distance runners, cyclists, swimmers, and other endurance athletes. We compare ourselves to them and end up postponing physical activity to some vague “someday” – because we assume we will never reach that level. Yet, looking after your body’s endurance is much easier than it seems.

Endurance training is most often associated with cardio training. There are many ways to improve endurance, and many of them can be done in virtually any environment – at the fitness club, at home, or outdoors. The most commonly mentioned endurance-building activities include:

• running,
• cycling,
• swimming,
• cross-country skiing,
• skipping rope,
• cross trainer/stepper,
• indoor rower,

In fact, many other activities – even those we do as hobbies or weave into our everyday routines – can also serve as endurance training. It’s all a matter of regularity and intensity. That’s why it’s worth paying attention to activities such as:

• walking and hiking (including Nordic walking, power walking, rucking),
• slow jogging,
• sports games and recreational activities,
• climbing stairs,
• dance,
• movement classes (Zumba, body combat).

How to build your aerobic base?

Every type of movement has a positive impact on the body’s endurance. What matters is how you move, and for how long. There are two main endurance training methods:

• continuous – maintaining a steady level of effort for a set period of time;
• interval – performing a set number of repetitions of a given exercise, alternated with rest breaks.

Continuous training can be anything from a several-kilometre run to a one-hour walk with a backpack. Interval training could mean a demanding interval session, but also a light jog-walk. The key is the intensity of the effort and the length of time you sustain it – in other words, the training zone you spend most time in.

Training zones are most commonly defined using HRmax – your maximum heart rate. There are many ways to calculate HRmax, and one popular formula looks like this:

• women: 207.2 – 0.65 x age
• men: 209.6 – 0.72 x age
• trained individuals: 205 – 0.6 x age
• untrained or occasionally active individuals: 212 – 0.7 x age

Once you know your maximum heart rate, you can establish your personal training zones – or let your activity tracker do it for you. There are five zones, each linked to a different intensity level and training goal:

• Zone 1 (up to 60% HRmax) – warm-up or post-training recovery; breathing is very easy, with minimal muscle strain.
• Zone 2 (60–70% HRmax) – light endurance training aimed at fat burning; slight muscle load, comfortable breathing.
• Zone 3 (70–80% HRmax) – aerobic endurance zone; breathing is still relatively easy, but the muscles begin to tire.
• Zone 4 (80–90% HRmax) – threshold power zone (aerobic/lactate threshold); breathing becomes heavy and muscle fatigue is noticeable.
• Zone 5 (over 90% HRmax) – anaerobic zone (maximum speed and power); breathlessness, exhaustion, and muscle pain.

An endurance recipe for beginners, the inactive, or those returning to exercise is simple and universal – build your aerobic base. You don’t need exceptional fitness levels to complete a workout in the second training zone and occasionally step into the third. That’s why the best way to get into the rhythm of endurance training is through short (15–20 minute) sessions at a steady, moderate intensity, gradually extending them according to your abilities and progress.

Of course, many people can manage longer and more intense workouts, but the principle remains the same – don’t dive straight into tough, demanding cardio training sessions (especially interval workouts) if you haven’t built a solid endurance base. Start with training that will deliver results within 4–6 weeks of regular effort – less body fat, improved muscle stamina, greater resistance to fatigue, smoother and deeper breathing, and better sleep quality. These benefits can be experienced by everyone, regardless of age, training history, or physical condition. All it takes is to get moving!

Endurance for busy people

The most common excuse for avoiding physical activity is lack of time. If household responsibilities, work, or childcare make it difficult to fit in classic volume training, consider weaving cardio into your daily routine – without strict workout plans, sacrifices, or pressure to achieve results. By introducing small changes that eventually become good habits, you can maintain a decent level of endurance for years to come. Here are some ideas worth putting into practice:

• Walk whenever you can. Get off the bus a stop earlier on your way to work, take the stairs instead of the lift, walk your dog for longer, and plan walking trips. It all counts!
• Choose two wheels over four. Riding a bike is great for your endurance – and in many cities, it’s often faster than driving. Choosing a bike can also save money on fuel and time spent searching for parking.
• Walking works wonders! You can get even more out of them by turning them into slow jogging sessions or rucking, which is walking with weight in a backpack.
• Better NEAT than nothing. Non-exercise activity won’t replace structured cardio training, but any kind of movement is better for your endurance than sitting in front of a screen.
• Together is better. Physical activity is always more enjoyable with company. Invite friends and family or find training partners for your endurance sessions.

Working on your endurance? Time for the next move – check out the range of cardio trainings available with your MultiSport card!

^References:

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