Use of a Time-based V-slope Method for Determination of Anaerobic Threshold
DOI:
https://doi.org/10.51224/SRXIV.551Keywords:
cardiopulmonary exercise testing, coefficient of repeatability, dAbstract
Three methods are commonly used for the determination of anaerobic threshold (AT): v-slope (VS), ventilatory equivalent (VEQ), and end-tidal (ET). For VS, VCO2 is plotted against VO2 (x-axis), and for VEQ and ET, each variable is plotted against elapsed time (x-axis). As these data points do not correspond to the same y-axis, these three methods cannot be directly compared. Purpose: To devise a way to construct a time-based VS graph. Methods: A new index, d, was created by subtracting VO2 from VCO2 and plotting the value against time. The d-AT was determined as the first ascending break point on the d graph. A database of 127 subjects (age: 51±21, 66 healthy subjects, 20 treated for cardiovascular risk factors, and 41 with cardiac disease) who underwent maximal symptom-limited exercise was used to assess the utility of this approach for detecting AT. Each of the four AT methods, employed independently and blinded to each other, were compared. Additionally, the reliability of each method was assessed using Altman’s level of agreement (coefficient of repeatability, CR). Results: The mean AT (mL/min) and its determination rate by d, VS, VEQ, and ET were 857±414 (90%), 939±407 (91%), 946 ±176 (74%), and 862±379 (79%), respectively (d/ET versus VS/VEQ, p<0.001). CR values (mL/min) were 117, 115, 152, and 175, respectively. AT determination by combining all three graphs (d, VEQ, ET) simultaneously did not improve CR but did reveal a delayed or suppressed ventilatory response (VEQ) in 48 subjects. Conclusions: The time-based v-slope, d-AT, was equivalent to v-slope method in AT determination rate and repeatability. One major advantage was that d-AT could graphically delineate different VCO2 and ventilation responses to exercise.
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Copyright (c) 2025 Hirotaka Nishijima, Kazuyuki Kominami, Toko Katsuragawa, Masatoshi Akino (Author)
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