For intensive care patients the return to normal life is usually along and strenuous journey. In addition to the severity of the underlying disease, possible comorbidities, sedation and pain management as well as the use of various drugs together with the length of stay in the intensive care unit are factors that strongly influence the course of early rehabilitation and thus the functional outcome. Intensive care patients in particular are exposed to extreme stress during mobilization and often reach their cardiopulmonary stress limit. In order to determine such limits, lactate measurement is used in the performance diagnostics of athletes. In aretrospective study 20intensive care patients were mobilized up to their subjective maximum load capacity during physiotherapy (sitting on the edge of the bed n = 6, standing n = 12 and walking n = 2). The lactate value was determined from the routine arterial blood gas analysis and then an attempt was made to establish acorrelation between the subjectively perceived change in exercise load (Borg CR10) and the changes in lactate measurements. Changes in the sense of an increase in stress occurred in both in the Borg scale and in the lactate measurements. The subjective maximum load capacity increased on average by 4.85points (p = 0.13, 95% confidence interval, CI 4.58-5.12). In addition, asignificant mean increase in lactate by 10.8 mg/dl (p < 0.001, 95% CI 9.73-11.87) was observed. No positive correlation between the load-induced changes in Borg values and the development of lactate values was shown (Pearson correlation: r = 0.123). The subjective load increase in the Borg CR10 observed in all 20intensive care patients included in the study and the associated significant increase in lactate after mobilization, suggest that an efficient load in the sense of atraining-desired supercompensation was achieved through mobilization. The tendency towards acorrelation between the changes in Borg CR10 and the lactate values can be interpreted as an indication that the development of lactate values can also be used in intensive care patients to avoid overloading of patients in early rehabilitation.