The Conconi Test - Searching for the Deflection Point

The Conconi Test (CT) is an incremental exercise test characterized by stages of equal intensity. For analysis speed (S) and HR (heart rate) are used. The deflection point of the HR/S graph marks the point where the linear relation between S and HR changes to a curvilinear one. As Conconi stated HR at deflection point represents anaerobic threshold (AT) value. Purpose of this study was to extend our previous research dealing with reliability and validity aspects of CT. Material and Methods: During 10 years (2007-2017) we tested 2 500 subjects using Conconi protocol. Tested were mainly football players and smaller number of runners (long distance and cross country) different ages and fitness level. Some subjects were tested repeatedly during the years. Initial speed of the running treadmill test was determined in the range of 10 to 12 km·h-1, according subjects age and fitness level. Speed was increased gradually every 150 m of 0.5 km·h-1 to the maximum speed when further increases were impossible. HR was recorded at every 150 meters. From a graphical representation dependence HR on increasing running speed we tried to find apparent diversion from the curve of linearity, labeled by Conconi as "deflection point" (DP). Simultaneously respiration values were recorded. From these respiration data we determined the ventilatory threshold (VT2) as a metabolic marker of the onset of blood lactate accumulation. Results: We found 6 types of response HR to increasing speed. a) regular DP; b) linear regression r ≥ 0.98 - no DP; c) linear regression r < 0.98 - no DP; d) inversion character of deflection point; e) DP not corresponding with value of ANP; f) more than one DP. As an AT predictor compared with VT2, Conconi test overestimated this value (0.5 km·h-1). Conclusion: Using of Conconi test as a predictor of ANP has a limitation. ANP values determined by CT are overestimated (0.5 km·h-1). Test stability of CT is very low and there is evidence that DP is not 100% repeated physiology phenomena.