A portable intensity guidance system for fitness training based on non-invasive detection of the lactate threshold

Daily moderate activity reduces markedly several population diseases. Still many persons do not perform any regular physical activity. Many persons quit because they exercise at too low intensity that does not give result, or at too high intensity that is not comfortable. By exercising at an established adequate workload, optimal for the individual, the person can see results of the training and the quitting behavior can be changed. In sport at top level, the lactate threshold is used as a guideline for adequate workload, and to see changes in fitness. The lactate threshold is generally established by blood tests. The aim of this project has been to evaluate a new method and a low cost sensor system, LACTA, that can identify the lactate threshold by analyzing the amount of Carbon dioxide in respiratory air, and to explore the value of the system when promoting physical activity of non-regularly active persons. LACTA is based on an electro acoustic sensor and needs no calibration by the user. The threshold found using LACTA correlates to the threshold established by blood analyses. LACTA is easy to use and each person can perform the test without help. The aim of the present study was to evaluate a new LACTA prototype without humidity and temperature diluting filter.