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Test-Retest Reliability and Minimum Detectable Change Using the K4b2: Oxygen Consumption, Gait Efficiency, and Heart Rate for Healthy Adults During Submaximal Walking
Journal article   Open access   Peer reviewed

Test-Retest Reliability and Minimum Detectable Change Using the K4b2: Oxygen Consumption, Gait Efficiency, and Heart Rate for Healthy Adults During Submaximal Walking

Benjamin J Darter, Kelly M Rodriguez and Jason M Wilken
Research quarterly for exercise and sport, Vol.84(2), pp.223-231
06/01/2013
DOI: 10.1080/02701367.2013.784720
PMID: 23930548
url
https://www.ncbi.nlm.nih.gov/pmc/articles/4023251View
Open Access

Abstract

Purpose: Oxygen consumption (VO 2 ; mLO 2 /kg/min), gait efficiency (GE; mlO 2 /kg/m) and heart rate (HR; beats per minute) are measures of physiological gait performance. However, the collection device, procedures for data normalization, and biological factors can affect measurement variability. The purpose of this study was to determine the test-retest reliability and minimum detectable change (MDC) for VO 2 , GE, and HR with the K4b 2 at submaximal walking speeds in healthy young adults. A second purpose was to determine if net measures improved reproducibility. Method: Twenty-two participants completed 2 identical treadmill tests on separate days at submaximal walking speeds from 0.71 m/s to 1.65 m/s. Results: Intraclass correlation coefficient (ICC) values for gross VO 2 , gross GE, and HR were greater than .85 for all walking speeds. Associated MDC values were approximately 7% to 10% for gross VO 2 and GE, and approximately 9% to 12% for HR. ICC values for resting VO 2 were lower, with MDC values approaching 25%. Subtracting out resting values to derive net VO 2 and GE values produced ICC values below .76 for the 2 slowest speeds but ICC values greater than .83 for the faster speeds. MDC values for net VO 2 and GE were up to 20% for the slowest speeds. Conclusions: The results demonstrate metabolic cost can be assessed reliably using the K4b 2 during submaximal walking and that gross measures are more reliable than net measures. Furthermore, changes at self-selected speeds exceeding 1.0 mLO 2 /kg/min in gross VO 2 and 0.01 mLO 2 /kg/m in gross GE can be considered a true change in walking performance.
reproducibility of results gait exercise test

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