Ammonia threshold--comparison to lactate threshold, correlation to other physiological parameters and response to training.

During standard graded exercise, blood lactate and blood ammonia levels increase in parallel and the two thresholds appear at the same relative intensity. The first part of this study aimed at comparing ammonia threshold to lactate threshold with five different graded exercise protocols. A significant difference between the two thresholds was found only in the continuous protocol with 4-min steps in which ammonia threshold appeared at a higher intensity than lactate threshold. The second part of the study investigated the correlation of ammonia threshold to some common physiological measurements. Correlation was significant with lactate threshold, ventilation threshold and endurance time. No correlation was found the anaerobic power, anaerobic capacity measurement and peak VO2. Ammonia threshold was also studied before and after endurance training and sprint training. The 8-week endurance training program was able to delay the appearance of ammonia threshold, but not the 8-week sprint training program. Findings in this study demonstrate that ammonia threshold is a physiological parameter that should be recognized and has potential to be applied for the evaluation of exercise capacity and the effectiveness of endurance training programs.