Spirometry - benefit from the determination of breathing gas

In the performance diagnostics, many methods have been established, with the aid of which the endurance performance of athletes can be determined. Especially the lactate level tests have prevailed in different variants.

Common to all approaches is that the performance that an athlete has to perform on an ergometer is increased in stages. This means that after increasing the intensity, this line will remain at the same level for a period of 3-5 minutes before further amplification follows. In addition to the classic lactate level test, spiroergometry (also known as ergo-spirometry) has established a method that further refines the diagnostic possibilities. Sebastian Mühlenhoff and Dennis Sandig describe the possibilities and limits of a procedure, with the help of which the findings of a performance diagnostic investigation can be extended.

If you want to control your endurance training, you need information about the effective areas of the training. By means of performance diagnostic procedures, each intensity level completed in the test is assigned a specific physiological response of the body. On the basis of the obtained data one then defines your training areas. So you can in training z. B. specifically affect your metabolism. Adjustments are created for a specific area. Only then can your performance run in pre-planned lanes. The most common test method for determining the appropriate training areas is the lactate level test, which can be used on any ergometer, eg. B. bicycle or treadmill is performed. The resistance is increased in stages and at the end of each stage a small amount of blood is taken from the capillary blood of the earlobe. Determining the concentration of the metabolic intermediate lactate, the aerobic and anaerobic threshold can be determined by various methods. In addition to training range determination and threshold setting, the test also provides basic information about your current endurance performance. In addition, the results help you to objectify your performance development.

Sensitive measurement with mask

In spiroergometry, on the other hand, the concentration of the gases is determined. This provides further valuable information that contributes to accurate performance diagnostics. Modern sensitive gauges capture every single one of your breaths and with it

- the oxygen uptake (VO2),

- the exhalation of carbon dioxide (VCO2),

- the tidal volume and

- the respiratory rate.

From these measured variables, a large number of further parameters and values ​​can be calculated. These include such direct values ​​as the ratio of oxygen uptake to carbon dioxide exhalation. This so-called respiratory quotient (RQ) allows conclusions to be drawn regarding the proportion of fats and carbohydrates in the respective energy supply. (1) This tells you how energy is provided for muscle work. Another important parameter is the respiratory equivalent for oxygen or for carbon dioxide (VE / VO2, VE / CO2). The respiratory equivalent indicates how many liters of air must be breathed to make one liter of oxygen available in the body or to breathe one liter of carbon dioxide.

From the magic word of maximum oxygen uptake

With spirometry, your maximum oxygen uptake can also be measured. This is often regarded as a gross criterion of endurance performance and therefore represents an important measure in performance diagnostics. It is determined in part by the training. However, the maximum achievable degree depends strongly on your personal genetic requirements. For this reason, maximum oxygen uptake may also help to assess the fitness of an athlete for endurance-oriented exercise. Sometimes it is also attempted to describe training areas by a percentage distribution - relative to the VO2max. The underlying assumption that heart rate and oxygen uptake are linear to each other, but is not proven. There are even indications that the two parameters just do not increase linearly. Another difficulty in determining VO2max is a methodological problem. If the maximum oxygen uptake capability is to be determined by the test, the step test is not the appropriate procedure. Ramp protocols are more suitable for this. In doing so, you as an athlete will be exposed within a maximum of 15 minutes as the resistance is continuously increased. (2) This results in a higher degree of utilization, and the values ​​are higher than those measured in a step test - which is due to the shorter load time. However, the question always arises as to how far the maximum measured VO2 value corresponds to the VO2max. Only when a plateau is recognizable in the course of oxygen uptake can we assume that we have measured the maximum oxygen uptake. But there are also cases in which no plateau is recognizable - then we have to resort to secondary criteria in order to ensure the exhaustion. The RQ, which should be over 1.1, can help here. At this point, we reiterate that your training areas can not be adequately determined via the VO2max. First, we would like to introduce you to the practical implementation of spirometry.

A high-precision measuring technology

The course of a spiroergometry initially does not differ from a classic performance diagnostics. There are even modern devices that can be used for transport, so that field tests can be carried out with spirometry. However, spiroergometry is usually done in the form of a classical step test. In this case, a mask is worn, so that the breathing air flows completely through the volume sensor. It usually contains a small fan and a sensor that records the volume of the breath and the breaths. Above this volume unit, a suction section ensures that with each breath part of the breathing air is sucked off and analyzed with regard to the oxygen or carbon dioxide content. This results in the aforementioned measured variables, which form the basis for the calculation of all other parameters.

If spiroergometry is carried out in the form of a step test, the lactate concentration is usually determined as well. This combination gives you valuable additional hints. This is also because the individual aerobic and anaerobic thresholds determined by the lactate concentration do not correspond directly with the spirometrically determined ventilatory thresholds. The combination of the measuring methods gives us 4 important measuring points, allowing a more comprehensive assessment of your performance. Above all, the training areas can be validated in this way. When performing a performance diagnosis, you should always make sure that the training areas are not standardized through a percentage distribution. It makes no sense to always maintain the same percentage of a training range for the different requirement profiles of the sports. For each athlete, the training areas must be interpreted individually from the results of a diagnosis.

From the V-Slope and the 9-field graphics

In addition, oxygen uptake (VO2) and carbon dioxide (VCO2) are measured. Both values ​​continue to increase under load - but at different speeds. If these two parameters are plotted on the time axis, conclusions about ventilatory thresholds can be drawn from the curve. There are several ways to determine thresholds in spirometry. Established methods include the V-Slop method and the Aquarius curves. (2) These methods are used to determine the ventilatory threshold (AT = anaerobic threshold) and the respiratory compensation point (RCP). The ventilatory threshold from spirometry theoretically corresponds to the aerobic threshold from the lactate level test, although it is also referred to as "anaerobic threshold". The respiratory compensation point corresponds to the anaerobic threshold of the lactate test. Depending on the protocol, however, the thresholds from lactate test and spirometry differ slightly in practice. Therefore, the experience of the test leader is important for a good quality evaluation. For this reason, the interpretation of such a test is also very difficult and requires a lot of experience.

In the form of the 9-field graphic according to Wassermann these and other values ​​are plotted graphically. With the help of a few fields, the individual threshold values ​​and the results of lactate diagnostics can be additionally checked and verified.

A good evaluation software allows for a manual correction by the diagnostician. So one can combine the individual experiences with the calculation methods. In addition to the mentioned parameters, the already mentioned respiratory quotient (RQ) is an important calculation parameter. From this it is possible to draw conclusions about the type of energy supply. A value below 1 means that less CO2 is exhaled than O2 can absorb. If the values ​​are between 0.75 and 0.8, it is assumed that the energy is mainly provided by the aerobic fat oxidation. (3) If the RQ reaches values ​​above 1, the anaerobic carbohydrate metabolism dominates. However, there are also theories that values ​​above 1 at the high stress levels are rather an indication that training was too intense and the body needs a regeneration phase. This assumption is interesting, especially when long-distance triathletes have very high scores, although the basic stamina was predominantly trained.

Benefit from the advantages of spiroergometry!

The large number of measured and calculated parameters allows you to see how complex such an evaluation is. That's why you should be careful to select a specialist. You recognize him by informing you in detail about the test variants before a test. Your own athletic ambitions and training condition should be taken into account in the evaluation and interpretation of the data. There are various methods for determining the thresholds, and the ventilatory thresholds represent other points in the test process compared to those in the case of pure lactates. Flat rate and fixed evaluations indicate that the software has spatulated the data out automatically.

Now that you have learned a lot about the procedure and the contents of spiroergometry, you have to ask yourself the question, which advantages can arise for you. It is important that your trainer has the opportunity to protect the ventilatory thresholds with the spirometry via the 9-field graphic. In combination with the thresholds determined by the lactate concentration, the training zones can be exactly limited. In a pure lactate level test, the limits of your training areas are usually set only at a fixed percentage of thresholds. Fewest diagnosticians have the necessary experience and take the trouble to consider, in addition to this fixation on the thresholds, the entire kinetics of the curve in their interpretation. With spirometry, one can clearly define the upper limit of the basic endurance range through reactions in the measured values. A direct assignment of an intensity level to the associated metabolic area is easier. This applies to all intensities and so also to the threshold training. For determining your training areas, spirometry can give you direct additional information. In addition, parameters such as the respiratory equivalent can make the training adjustments in the aerobic metabolic area very sensitive. In addition to the possibility to best secure the relevant parameters for performance diagnostics and training control by means of ergospirometry, further important pulmonary findings can be obtained. On the basis of the characteristic of the breathing depth and the respiratory rate with increasing load possibly existing obstructive or restrictive restrictions in the respiration can be diagnosed. Increased breathing resistance has a strong performance-limiting effect and is not uncommon among endurance athletes.

Practical tips

- Spiroergometry should be well prepared.

- 2 days before a test you should train only regenerative.

- Carbohydrate-rich diet in the days before a test is important.

- Do not plan more than 2-3 tests per year.

- Do not let the training areas derive from the VO2max.

- The lactate thresholds and the ventilatory thresholds help to determine your training areas exactly.

Dennis Sandig MA, Research Assistant at the Julius-Maximilians-University Würzburg and Doctoral Student at the University of the Saarland; Co-founder of iQ athletik GmbH

Sebastian Mühlenhoff MA, Head of the Performance Diagnostics Department at iQ athletik GmbH and is Sport Science Coordinator of the Hessian Cyclist Association (HRV)


1. Wilmore, J. & Costill, D. (2004) Physiology of Sport and Exercise. Champaign: Human Kinetics

Hollmann, W. et al. (2006), Spiroergometry. Stuttgart: Schattauer

3. Schurr, S. (2007), Performance Diagnostics - The Lactate Performance Test and its Alternatives. Norderstedt: Books on Demand GmbH


DNA (deoxyribonucleic acid) - the substance in the nucleus that carries genetic information.

Spiroergometry (also ergo-spirometry) - Measuring the respiratory gases on an ergometer with the help of a breathing mask

Capillary blood - Blood from the finest blood vessels, which represents a balanced ratio of venous and arterial parts. For example, it is taken from the earlobe or from the fingertip.

Respiratory quotient - the RQ represents the ratio of oxygen uptake and carbon dioxide abatement.

Respiratory Equivalent - The amount of air that must be inhaled or exhaled to absorb 1 liter of O2 or to exhale CO2.

Further articles:

Individual performance diagnostics and training control for recreational athletes

Tests for runners

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