Objective: 

The aims of this study were to compare the accuracy of Conconi and V-Slope methods used in Anaerobic threshold (AT) estimation and also determine the validity of a new method based on work rate divided to heart rate ratio (i.e. modifying Conconi method) on AT estimation.

Methods: 

Twenty trained male subjects (19±0.7 yr, 61.3±1.7 kg) have participated to the study after giving signed written informed consents, which were approved by the local ethical committee. Each subject performed an incremental exercise test (15 W/min) using an electromagnetically braked cycle ergometer. Ventilatory and gas exchange parameters were evaluated breath-by-breath. The heart rate was recorded as beat-by-beat. AT estimated using V-Slope, heart rate plotted versus work load and also heart rate divided to work rate plotted versus VO2. A paired t- test was used to evaluate the values.

Results: 

Heart rate-work rate relationships were observed as linear increases in 15 subjects, left side deflection in 3 subjects (associated with the V-slope break point) and right side deflection in 2 subjects. The work rate to heart rate ratio showed a clear break point in all subjects and closely associated with the V-slope break point: 1.89±0.03 L/min vs 1.92±0.04 L/min (p=0.2).

Conclusions: 

In conclusion, absent of break point in heart rate work rate relationship (75%) and extremely low percent of association in AT estimation between Conconi and V-slope method (15%) may reduce reliability of Conconi test. Thus, caution should be taken by investigators especially when making important decision for patients and sports training. However, work rate to heart rate ratio could provide easy and reliable AT estimation.