The Validity and Reliability of a Tire Pressure-Based Power Meter for Indoor Cycling

• Main Authors: Nicholas J. Fiolo, Hai-Ying Lu, Chia-Hsiang Chen, Philip X. Fuchs, Wei-Han Chen, Tzyy-Yuang Shiang
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Series: Sensors
• Subjects: SRM; cycling technology; validation; tire pressor sensor
• Online Access: https://www.mdpi.com/1424-8220/21/18/6117

The purpose of this study was to evaluate the validity and reliability of a tire pressure sensor (TPS) cycling power meter against a gold standard (SRM) during indoor cycling. Twelve recreationally active participants completed eight trials of 90 s of cycling at different pedaling and gearing combinations on an indoor hybrid roller. Power output (PO) was simultaneously calculated via TPS and SRM. The analysis compared the paired 1 s PO and 1 min average PO per trial between devices. Agreement was assessed by correlation, linear regression, inferential statistics, effect size, and Bland–Altman LoA. Reliability was assessed by ICC and CV comparison. TPS showed near-perfect correlation with SRM in 1 s (<i>r</i>_s = 0.97, <i>p</i> < 0.001) and 1-min data (<i>r</i>_s = 0.99, <i>p</i> < 0.001). Differences in paired 1 s data were statistically significant (<i>p</i> = 0.04), but of a trivial magnitude (<i>d</i> = 0.05). There was no significant main effect for device (F(1,9) = 0.05, <i>p</i> = 0.83, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi mathvariant="sans-serif">η</mi><mi>p</mi><mn>2</mn></msubsup></mrow></semantics></math></inline-formula> = 0.97) in 1 min data and no statistical differences between devices by trial in post hoc analysis (<i>p</i> < 0.01–0.98; <i>d</i> < 0.01–0.93). Bias and LoA were −0.21 ± 16.77 W for the 1 min data. Mean TPS bias ranged from 3.37% to 7.81% of the measured SRM mean PO per trial. Linear regression SEE was 7.55 W for 1 min TPS prediction of SRM. ICC_3,1 across trials was 0.96. No statistical difference (<i>p</i> = 0.09–0.11) in TPS CV (3.6–5.0%) and SRM CV (4.3–4.7%). The TPS is a valid and reliable power meter for estimating average indoor PO for time periods equal to or greater than 1 min and may have acceptable sensitivity to detect changes under less stringent criteria (±5%).