Ergometry & lactate testing

Ergometry is an exercise test on a stationary bicycle. While you pedal and the load increases in stages, we record your ECG, pulse and blood pressure and, as a rule, also measure the lactate in your blood. This shows how your heart and circulation respond to exertion, how fit you are and how well your mitochondria supply energy. Some things that go unnoticed at rest only become visible under exertion, for example hidden high blood pressure.

Medical indications for an exercise ECG

• Chest pain on physical exertion
• High blood pressure
• Heart rhythm disorders
• Too much cholesterol, homocysteine, blood sugar
• Smoking, stress, lack of exercise
• Assessing the severity of a narrowing of the coronary arteries
• Before surgery
• Certain occupations and groups (e.g. pilots, bus drivers, older athletes, professional athletes)

Preparation

Do not arrive at the clinic in a rush or with sore muscles from training. You should not be fasting, but should not have eaten a large meal beforehand either. If possible, wear a tracksuit or light clothes, trainers and socks. You may shower before the test, but do not apply body lotion, as this impairs the contact of the electrodes. You will probably sweat during the test, so please bring a flannel and a towel. You will appreciate freshening up afterwards.

How it works

Depending on your fitness, the whole test takes about 15–30 minutes. Please make sure the bicycle seat is at a comfortable height, i.e. your legs should be almost straight when the pedal is at the bottom. First the ECG electrodes, a blood pressure cuff on your arm and an oxygen monitor are attached. Cycling starts at 50 watts. Every 2 minutes your blood pressure is measured, the ECG recorded and the load increased by a further 25–50 watts. As a rule, lactate measurements are also taken to assess mitochondrial metabolism.

When the target work capacity or maximum heart rate is reached, or if symptoms occur (tightness in the chest, leg pain, shortness of breath, nausea, dizziness, etc.), which you must report immediately, the test is stopped. Your pulse and blood pressure continue to be measured over the following minutes to determine the recovery time needed. This increases with age (compare small children at play, who hardly ever need to "recover").

Lactate measurement

At each load level we measure the lactate in your blood as well as your pulse and blood pressure. This shows how well your mitochondria are working.

What the lactate curve shows and in which lactate zones you should train is explained on the page Lactate exercise test.

Sample results

• The red band is the blood pressure, between the upper and the lower value.
• The dark line is the pulse.
• The grey steps show the load on the bicycle.

Good result

Pulse and the upper blood pressure value rise steadily from stage to stage, while at the same time the lower blood pressure value falls, up to 200 watts. They return quickly to their starting values once the exertion ends.

Hidden high blood pressure

At rest the blood pressure hardly stands out, but under exertion the upper value rises to almost 240 mmHg. Without an exercise test this would go undetected.

Blood pressure medication too strong

Despite the exertion the blood pressure does not rise but falls, and the test ends after only five minutes at 100 watts.

Back to normal without blood pressure medication

Without the medication, blood pressure and pulse rise with the exertion again.

Chronic fatigue

The pulse is already raised at the start and rises only a little further. The exertion ends after a good six minutes at 100 watts.

ME/CFS

The pulse rises to around 180 beats per minute, while the blood pressure increases only slightly. The load reaches 125 watts. What is striking and characteristic is that the pulse is always higher than the systolic blood pressure. In the other charts the pulse curve never rises above the red zone.

Performance and reserve: why the wattage matters

Life is not a static state. It needs energy all the time, much as an engine needs fuel and air. The cells obtain this energy with the help of oxygen. How much a person can do therefore depends on how much oxygen the lungs, heart and circulation deliver to the muscles and how well the mitochondria use it. Ergometry measures the result in watts.

Healthy adults usually reach between 100 and 250 watts on the cycle ergometer, depending on height, age and sex; well-trained endurance athletes reach considerably more. You can read your personal target performance from the nomogram above.

What living costs in watts

Even at rest the body uses energy for the heart, breathing, brain and body heat. Medicine calls this basic requirement 1 MET. The wattage on the ergometer shows what performance is possible beyond that. Some guide values, converted for a person weighing 75 kg:

• Around 50 watts (4 METs): this is what it takes to climb two flights of stairs. Those who cannot manage this are at higher risk during an operation. The European guideline of 2022 therefore includes this information in the assessment before surgery.
• Around 50 to 75 watts: the threshold of independence. If maximal oxygen uptake falls below 18 ml per kg per minute in men and below 15 ml in women, living independently becomes unlikely. Without training this threshold is reached on average at 80 to 85 years of age.
• Around 25 watts more (1 MET): in an analysis of around 750,000 exercise tests, each additional MET was associated with a 14 per cent lower risk of death, in women and men and into old age.

The reserve

What matters is the gap between the most you can do and what the body needs at that moment. This reserve is available for everything that goes beyond daily life: an infection, an operation, prolonged stress. Someone who manages 200 watts has plenty of leeway. Someone who reaches only 60 watts needs almost all of it just for the stairs. If an illness is added, little is left for the vital functions.

This explains why fatigue sets in so early during illness and why infections and operations are more dangerous in old age. Breathlessness even at rest is a sign that the reserve is used up and should be assessed by a doctor.

The decline with age

Performance declines with age, but not evenly. In a long-term study of healthy adults, maximal oxygen uptake fell by 3 to 6 per cent per decade between the ages of 20 and 40, and by more than 20 per cent per decade from the age of 70. Physically active people lost it at a similar rate but were higher at every age. Those who enter old age with a higher performance reach the critical thresholds later.

Performance and life expectancy

An analysis of around 122,000 exercise tests (2018) found a risk of death about five times as high in the group with the lowest fitness as in the group with the highest. No upper limit to the benefit was seen. Low fitness weighed at least as heavily as smoking, diabetes or coronary heart disease.

These are observations in large groups and not a prediction for the individual. But they show that the wattage is more than a sporting figure: it describes how much reserve the body has left for its vital functions. Regular endurance training can slow the decline, and ergometry makes the progress measurable.

Sources: Mandsager et al., JAMA Network Open 2018. Kokkinos et al., Journal of the American College of Cardiology 2022. Fleg et al., Circulation 2005. Shephard, British Journal of Sports Medicine 2009. Guideline of the European Society of Cardiology on non-cardiac surgery, 2022.

Ergometry shows how the heart, circulation and metabolism actually work under exertion. These functional results form a solid basis for further therapeutic measures and for optimising them.