Introduction and aims: In order to determine
a person’s physical capacity, spiroergometric
assay of the respiratory quotient
(RQ) is a common tool in occupational medicine.
Our aim in the present study was to determine
whether the use of the blood lactate
concentration, which is common in sports
medicine, can also be validated for determination
of performance loss in patients.
Methods: During spiroergometric tests on
744 patients with different diseases, mostly
of the lungs and airways, both the respiratory
(RQ = 1) and the metabolic anaerobic threshold
(blood lactate concentration = 4 mmol/L)
were determined.
Results: The work capacity ranged between
25 and 150 watt with a mean value of 100 watt.
About 40 % of the individuals examined exceeded
the respiratory threshold and the
metabolic anaerobic threshold. There were
no significant differences between patients
with various categories of diseases. Although
the respiratory anaerobic threshold was exceeded
at an average work capacity approximately
25 watts lower, the two parameters
were relatively well correlated (r = 0.75).
Discussion and conclusions: Because of the
conceivable confounding factors in the determination
of both the respiratory threshold
and the metabolic anaerobic threshold,
an assessment using a combination of both
methods can be regarded as optimum.