The relevance of the respiratory quotient (RQ) and lactate for the determination of the impaired earning capacity status

Project No. FF-FB 0128


completed 10/2007


Spiroergometry is frequently used in patients with occupational diseases of the lung and the respiratory tract. Spiroergometry results are well established for early detection of reduced exercise capacity. Therefore this spiroergometry is recommended in the "Reichenhaller Merkblatt". The study examines if the analysis of lactate in the blood of patients with occupational diseases of the lung and the respiratory tract is useful for the determination of the earning capacity status.


The respiratory quotient (RQ) depends on a lot of factors and is an appropriate reference parameter for the anaerobic and aerobic threshold. The examination of the lactate in the capillary blood is a common method in the sports medicine to determine the exercise capacity. In this study the value of lactate in the blood should be compared to the RQ as standardized method in patients with occupational diseases of the lung and the respiratory tract.


Computer-aided spirometry has proven to be a reliable method for estimation of an MdE (reduced earning capacity) in occupational medicine. The determination of the anaerobic threshold by use of the respiratory quotient (RQ) as a parameter of cardiopulmonary performance has been established. The RQ is dependent on numerous factors. Similar to analyses used in sports medicine, the lactate levels in capillary blood can be used as an additional parameter for diagnostic measurement of the anaerobic threshold (AS).
The RQ and lactate levels are valuable parameters for the determination of cardiopulmonary performance capability, and are important in establishing the MdE in occupational medicine. Lactate determination is a simple, practical, and inexpensive way of estimating the performance capabilities of patients with diagnosed occupational diseases. Ergometric methods that take into account both aspects should be considered optimal.

Last Update:



Financed by:
  • Deutsche Gesetzliche Unfallversicherung e.V. (DGUV)
Research institution(s):
  • Universität Giesssen

-cross sectoral-

Type of hazard:



occupational disease

Description, key words:

lactate, respiratory tract, diseases of the lung, impairment of earning capacity