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Determination of both the time constant of v̇O 2 and Δv̇O 2 /Δ W from a single incremental exercise test: validation and repeatability
Author(s) -
Wisén Anita G. M.,
Wohlfart Björn
Publication year - 2004
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2004.00555.x
Subject(s) - medicine , repeatability , statistics , mathematics
Summary A single incremental cycle exercise test including a steady‐state load, combined with respiratory gas exchange, was performed with the objective of determining the time constant ( o 2 ) and the amount of oxygen required at each load ( o 2 /Δ W ) by using a novel equation. The protocol was validated using four exercise tests at different constant loads and conventionally fitted mono‐exponential functions to determine o 2 , and interpolation of o 2 versus load to determine o 2 /Δ W . No significant differences were seen between the means of either o 2 or o 2 /Δ W determined with the two protocols. The correlation coefficient was 0·62 for o 2 and 0·48 for o 2 /Δ W . The absolute differences (2 SD) were 11·6 s for o 2 and 1·1 ml min −1 W −1 for o 2 /Δ W . The equations were compared in the same steady‐state test and good agreement of o 2 was obtained ( R = 0·99). The 5–6‐week repeatability (incremental test) was evaluated. No statistical differences were seen between the mean of the repeated tests. The difference between the tests (2 SD) were 20 s for o 2 and 1·2 ml min −1 W −1 for o 2 /Δ W . In conclusion, o 2 and o 2 /Δ W can be determined from a single incremental test. The validation showed an acceptable agreement, although the variations in absolute values were not negligible. This could partly be explained by the natural day‐to‐day variation and fluctuations in incoming raw data. The test–retest variation in absolute values was considerable, which must be taken into account when using o 2 and o 2 /Δ W for evaluation of aerobic function.