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Reliability of Power Settings of the Wahoo KICKR Power Trainer After 60 Hours of Use

DOI:10.1123/ijspp.2016-0732
Authors:
Emma Zadow at La Trobe University
Emma Zadow
Cecilia M Kitic at The University of Queensland
Cecilia M Kitic
Sam Shi Xuan Wu at Swinburne University of Technology
Sam Shi Xuan Wu
James Fell at University of Tasmania
James Fell
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Abstract

Purpose: The purpose of this study was to assess the reliability of power output measurements of a Wahoo KICKR Power Trainer (KICKR) on two separate occasions, separated by fourteen months of regular use (~1 h per week). Methods: Using the KICKR to set power outputs, powers of 100-600W in increments of 50W were assessed at cadences of 80, 90 and 100rev.min(-1) which were controlled and validated by a dynamic calibration rig (CALRIG). Results: A small ratio bias of 1.002 (95%rLoA: 0.992-1.011) was observed over 100-600W at 80-100rev.min(-1) between Trial 1 and Trial 2. Similar ratio biases with acceptable limits of agreement were observed at 80rev.min(-1) (1.003 (95% 0.987-1.018)), 90rev.min(-1) (1.000 (95%rLoA: 0.996-1.005)) and 100rev.min(-1) (1.002 (95%rLoA: 0.997-1.007)). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) for mean power (W) between trials was 1.00 (95%CI: 1.00-1.00) with a typical error (TE) of 3.1W and 1.6% observed between Trial 1 and Trial 2. Conclusion: When assessed at two separate time points fourteen months apart, the KICKR has acceptable reliability for combined power outputs of 100-600W at 80-100rev.min(-1), reporting overall small ratio biases with acceptable limits of agreement and low TE. Coaches and sports scientists should feel confident in the measured power output by the KICKR over an extended period of time when performing laboratory training and performance assessments.
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Abstract
Purpose: The purpose of this study was to assess the reliability of power output measurements
of a Wahoo KICKR Power Trainer (KICKR) on two separate occasions, separated by fourteen
months of regular use (~1 h per week). Methods: Using the KICKR to set power outputs,
powers of 100-600W in increments of 50W were assessed at cadences of 80, 90 and
100rev.min-1 which were controlled and validated by a dynamic calibration rig (CALRIG).
Results: A small ratio bias of 1.002 (95%rLoA: 0.992-1.011) was observed over 100-600W at
80-100rev.min-1 between Trial 1 and Trial 2. Similar ratio biases with acceptable limits of
agreement were observed at 80rev.min-1 (1.003 (95% 0.987-1.018)), 90rev.min-1 (1.000
(95%rLoA: 0.996-1.005)) and 100rev.min-1 (1.002 (95%rLoA: 0.997-1.007)). Intraclass
correlation coefficients (ICC) with 95% confidence intervals (CI) for mean power (W) between
trials was 1.00 (95%CI: 1.00-1.00) with a typical error (TE) of 3.1W and 1.6% observed
between Trial 1 and Trial 2. Conclusion: When assessed at two separate time points fourteen
months apart, the KICKR has acceptable reliability for combined power outputs of 100-600W
at 80-100rev.min-1, reporting overall small ratio biases with acceptable limits of agreement and
low TE. Coaches and sports scientists should feel confident in the measured power output by
the KICKR over an extended period of time when performing laboratory training and
performance assessments.
Keywords: reproducibility, power, ergometry, training

Supplementary resource (1)

reliability of power settings of the KICKR after 60 h of use
Data
May 2017
Emma Zadow · Cecilia M Kitic · Sam Shi Xuan Wu · James Fell
... Since development of the laboratory-based 3MT in 2006, the availability of accurate and reliable power-measuring devices for use during indoor cycle training has increased dramatically (Hoon et al. 2016;Zadow et al. 2016Zadow et al. , 2018. As the 3MT only requires accurate measurement of power output and time, it is theoretically possible that the 3MT could be used by athletes in remote settings using personal equipment without supervision for quantification of MMSS and W′. ...
... The sub-group of participants completing the validity phase of the study used either a Wahoo Kickr (N = 9, Wahoo Fitness, Atlanta, USA) or Tacx Neo 2 T (N = 1, Garmin ® , KS, USA) to measure power output. The reliability and validity of the Wahoo Kickr has been established (Hoon et al. 2016;Zadow et al. 2016Zadow et al. , 2018, whereas the Tacx Neo 2 T has to our knowledge not been validated in research; however, the data from this individual participant support credible reliability within this study (within-subject coefficient of variation for V O 2 during 5-8 min of the standardised warm-up in the validity trials, 2.5%). ...
A three-minute all-out test performed in a remote setting does not provide a valid estimate of the maximum metabolic steady state
Article
Full-text available
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... All cyclists used the same bike (2017 Roubaix One. 3 size 56; Fuji, Taichung, Taiwan) mounted on a cycle ergometer (KICKR; Wahoo Fitness, Atlanta, GA) considered to be valid and reliable. 22,23 Saddle position was individually adjusted, and measures were noted for replication. The bike was equipped with a crank-based power meter (SRAM S975; SRM, Jülich, Germany), from which power output and cadence were recorded. ...
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... After conclusion of the resting measure, subjects performed a five-minute, self-selected warm-up on their stationary bike. Athletes performed bicycle VO2max testing with their racing bicycles attached to a stationary ergometer (Zadow et al. 2018). Wattage was controlled via Bluetooth. ...
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Thesis
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  • Apr 2018
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... Thus, for a cycle trainer or power meter to be useful in a research setting it must have similar qualities of measurement. Different researchers have tested the validity of other mobile ergometers such as Tacx Fortius (Peiffer and Losco, 2011), KICKR Power Trainer (Zadow et al., 2017;Zadow et al., 2016), LeMond Revolution (Novak et al., 2015), and Elite Axiom Powertrain (Bertucci et al., 2005a), as well as other mobile power meters, including PowerTap Hub (Bertucci et al., 2005b;Bouillod et al., 2016;Gardner et al., 2004) and Garmin Vector (Bouillod et al., 2016;Nimmerichter et al., 2017;Novak and Dascombe, 2016). It should be noted that the SRM, as the reference power meter, is also affected by some measurement error. ...
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Caveats and Recommendations to Assess the Validity and Reliability of Cycling Power Meters: A Systematic Scoping Review
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Article
  • Aug 2016
Mobile power meters provide a valid means of measuring cyclists’ power output in the field. These field measurements can be performed with very good accuracy and reliability making the power meter a useful tool for monitoring and evaluating training and race demands. This review presents power meter data from a Grand Tour cyclist’s training and racing and explores the inherent complications created by its stochastic nature. Simple summary methods cannot reflect a session’s variable distribution of power output or indicate its likely metabolic stress. Binning power output data, into training zones for example, provides information on the detail but not the length of efforts within a session. An alternative approach is to track changes in cyclists’ modelled training and racing performances. Both critical power and record power profiles have been used for monitoring training-induced changes in this manner. Due to the inadequacy of current methods, the review highlights the need for new methods to be established which quantify the effects of training loads and models their implications for performance.
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Validity of Power Settings of the Wahoo KICKR Power Trainer
Article
Purpose: The purpose of this study was to assess the validity of power output settings of the Wahoo KICKR Power Trainer (KICKR) using a dynamic calibration rig (CALRIG) over a range of power outputs and cadences. Methods: Using the KICKR to set power outputs, powers of 100-999W were assessed at cadences (controlled by the CALRIG) of 80, 90, 100, 110 and 120rpm. Results: The KICKR displayed accurate measurements of power between 250-700W at cadences of 80-120rpm with a bias of -1.1% (95%LoA: -3.6-1.4%). A larger mean bias in power were observed across the full range of power tested, 100-999W 4.2% (95%LoA: -20.1-28.6%), due to larger biases between 100-200W and 750-999W (4.5%, 95%LoA:-2.3-11.3% and 13.0%, 95%LoA: -24.4-50.3%), respectively. Conclusion: When compared to a CALRIG, the Wahoo KICKR Power Trainer has acceptable accuracy reporting a small mean bias and narrow limits of agreement in the measurement of power output between 250-700W at cadences of 80-120rpm. Caution should be applied by coaches and sports scientists when using the KICKR at power outputs of <200W and >750W due to the greater variability in recorded power.
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Statistical-Methods For Assessing Agreement Between 2 Methods Of Clinical Measurement
Article
  • Apr 2010
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
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Accuracy of the Velotron Ergometer and SRM Power Meter
Article
  • Feb 2009
The purpose of this study was to determine the accuracy of the Velotron cycle ergometer and the SRM power meter using a dynamic calibration rig over a range of exercise protocols commonly applied in laboratory settings. These trials included two sustained constant power trials (250 W and 414 W), two incremental power trials and three high-intensity interval power trials. To further compare the two systems, 15 subjects performed three dynamic 30 km performance time trials. The Velotron and SRM displayed accurate measurements of power during both constant power trials (<1% error). However, during high-intensity interval trials the Velotron and SRM were found to be less accurate (3.0%, CI=1.6-4.5% and -2.6%, CI=-3.2--2.0% error, respectively). During the dynamic 30 km time trials, power measured by the Velotron was 3.7+/-1.9% (CI=2.9-4.8%) greater than that measured by the SRM. In conclusion, the accuracy of the Velotron cycle ergometer and the SRM power meter appears to be dependent on the type of test being performed. Furthermore, as each power monitoring system measures power at various positions (i.e. bottom bracket vs. rear wheel), caution should be taken when comparing power across the two systems, particularly when power is variable.
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Dynamic calibration of mechanically, air- and electromagnetically braked cycle ergometers
Article
In this study we measured the accuracy of the following types of cycle ergometer against the criterion of a dynamic calibration rig (DCR): 35 friction-braked (Monark), 5 research-grade air-braked (Repco) and 5 electromagnetically braked (2 Siemens, 1 Elema-Schonander, 1 Ergoline, 1 Warren E. Collins). Monark ergometer power outputs over the range 58.9-353.2 W significantly (P < 0.001) underestimated those registered by the DCR with mean accuracies of 91.7-97.8%. The least accurate individual reading for each of the six up-scale (0-353.2 W) power outputs ranged from 81.6 to 91.6%; corresponding down-scale (353.2-0 W) accuracies were 85.1-92.5%. A hysteresis effect was furthermore evident for this ergometer in that up-scale measurements were significantly (P < 0.05) greater than down-scale ones. In addition, when the oldest [mean (SD): 11.3 (2.3) years old] and newest [1.4 (0.8) years old] eight ergometers were compared, the latter were significantly (P < 0.05) more accurate over the range 117.7-294.3 W. Apart from the two lowest power outputs of 47 W (62.2-96.0% accuracy) and 127 W (88.0-97.7% accuracy), the individual up-scale and down-scale accuracies of the Repco ergometers ranged from 98.0 to 104.2% for power outputs of 272.7-1137.8 W and the means were not significantly different from those of the DCR. There was also no evidence of hysteresis. Except for the initial power output of 50 W (40 rev/min: 83.8-99.2% accuracy; 60 rev/min: 93.2-122.6% accuracy), the individual accuracies of the electromagnetically braked ergometers ranged from 89.3 to 101.4% over the up-scale range of 100-400 W, and none of the means were significantly different from those of the DCR. The variability of individual errors for the preceding data emphasises that all cycle ergometers should be validated against the criterion of a DCR if accurate power outputs are required.
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