Baumgartl P, Aigner A
Wien Med Wochenschr. 1985 May 31;135(9-10):241-4.
In endurance sports heart frequency at the aerobic threshold (2 mmol/l lactate) is recommended for extensive training and heart rate at the anaerobic threshold (4 mmol/l lactate) for intensive training. Both values could be estimated by means of exercise tests in the laboratory as well as in the field. However for training-recommendations only data estimated on a specific exercise procedure should be used.