{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T15:56:38Z","timestamp":1785426998534,"version":"3.56.0"},"reference-count":44,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T00:00:00Z","timestamp":1776643200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Open Access Publishing Fund of Leipzig University"},{"id":[{"id":"https:\/\/ror.org\/03s7gtk40","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Inertial measurement units (IMUs) present promising avenues for performance diagnostics in skateboarding, yet systematic validation of their accuracy and applicability remains limited. This study validates the commercially available Spinnax Freak IMU system in the context of skateboarding, with a focus on selected trick detection and classification, distance measurement, maximal horizontal speed, maximal vertical height of the skateboard and airtime during a jump trick. A total of 23 skateboarders (4 females, 19 males; 27.4 \u00b1 10.9 years) participated in this study. Validation methods included comparisons with established reference systems such as laser ranging for maximal horizontal speed (LAVEG), 2D video analysis for maximal vertical height of the skateboard (Kinovea), light barrier measurements for airtime detection (OptoJump Next), and a fixed metric reference (10 m) for rolling distance measurements. The evaluation was supported by statistical analyses including mean absolute error (MAE), root mean-square error (RMSE), mean absolute percentage error (MAPE), t-tests, Bland\u2013Altman plots, linear regression, and ICC(3,1). The Spinnax Freak system demonstrated high validity in detecting trick events and in providing distance measurements that were statistically equivalent to the reference. Trick classification, maximal horizontal speed, maximal vertical height of the skateboard and airtime showed substantial errors, indicating that these outputs are not reliable for biomechanical interpretation at this point. These findings highlight both the potential and the current constraints of single-sensor setups for field-based motion capture in skateboarding. Future developments should prioritize algorithmic refinement, improved temporal resolution, and optimized event classification to enhance measurement accuracy and expand applicability in biomechanical analysis and automated training documentation in skateboarding.<\/jats:p>","DOI":"10.3390\/s26082537","type":"journal-article","created":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T13:22:47Z","timestamp":1776691367000},"page":"2537","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Validity of a Commercially Available Inertial Measurement Unit for Artificial Intelligence-Based Trick Detection and Kinematic Performance Assessment in Skateboarding"],"prefix":"10.3390","volume":"26","author":[{"given":"Birte","family":"Scholz","sequence":"first","affiliation":[{"name":"Institute for General Training and Movement Sciences, Faculty of Sports Science, Leipzig University, 04109 Leipzig, Germany"},{"name":"Department of Engineering and Industrial Design, Magdeburg-Stendal University of Applied Sciences, 39110 Magdeburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-1340-258X","authenticated-orcid":false,"given":"Niklas","family":"Noth","sequence":"additional","affiliation":[{"name":"Institute for Applied Training Science, 04109 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2159-7785","authenticated-orcid":false,"given":"Maren","family":"Witt","sequence":"additional","affiliation":[{"name":"Institute for General Training and Movement Sciences, Faculty of Sports Science, Leipzig University, 04109 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6822-5201","authenticated-orcid":false,"given":"Olaf","family":"Uebersch\u00e4r","sequence":"additional","affiliation":[{"name":"Department of Engineering and Industrial Design, Magdeburg-Stendal University of Applied Sciences, 39110 Magdeburg, Germany"},{"name":"Institute for Applied Training Science, 04109 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,20]]},"reference":[{"key":"ref_1","unstructured":"IOC (2016). Tokyo-2020-Olympic-Programme-Commission-Report, Olympic World Library."},{"key":"ref_2","unstructured":"IOC (2025, October 31). Skateboard: Olympische Geschichte, Regeln, Letzte Neuigkeiten und kommende Events f\u00fcr den Olympischen Sport. Available online: https:\/\/www.olympics.com\/de\/sportarten\/skateboarding\/."},{"key":"ref_3","unstructured":"IOC (2025, October 30). Los Angeles 2028 Olympics: IOC Approves Surfing, Skateboarding, and Sport Climbing for Games. Available online: https:\/\/www.olympics.com\/en\/news\/surfing-skateboarding-sport-climbing-approved-los-angeles-la2028-games."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1399","DOI":"10.1007\/s40279-024-02032-1","article-title":"Skating into the Unknown: Scoping the Physical, Technical, and Tactical Demands of Competitive Skateboarding","volume":"54","author":"Diewald","year":"2024","journal-title":"Sports Med."},{"key":"ref_5","unstructured":"Heter, J., and Simpson, J.T. (2025). Skateboarding and Philosophy: Essays Concerning the Life of the Grind, McFarland."},{"key":"ref_6","unstructured":"Gr\u00e4tz, F. (2025, November 23). DRIV Skateboarding. Available online: https:\/\/rtk.skateboarding.sport-iat.de\/skateboarding#c5490."},{"key":"ref_7","unstructured":"Worldskate (2025, September 23). Los Angeles 2028 Judging Criteria-V5. Available online: https:\/\/skateboardgb.org\/wp-content\/uploads\/2025\/08\/Los-Angeles-2028-Judging-Criteria-V5-1.pdf."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Palazzo, L., Suglia, V., Grieco, S., Buongiorno, D., Brunetti, A., Carnimeo, L., Amitrano, F., Coccia, A., Pagano, G., and D\u2019Addio, G. (2025). A Deep Learning-Based Framework Oriented to Pathological Gait Recognition with Inertial Sensors. Sensors, 25.","DOI":"10.3390\/s25010260"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"296","DOI":"10.1016\/j.orthtr.2019.06.001","article-title":"Measuring biomechanical loads and asymmetries in junior elite long-distance runners through triaxial inertial sensors","volume":"35","author":"Fleckenstein","year":"2019","journal-title":"Sports Orthop. Traumatol."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Uebersch\u00e4r, O., Riedl, M., Fleckenstein, D., and Falz, R. (2026). Effects of Acute Altitude, Speed and Surface on Biomechanical Loading in Distance Running. Sensors, 26.","DOI":"10.3390\/s26010276"},{"key":"ref_11","first-page":"11236","article-title":"Quantitative analysis of athlete performance in artistic skating using IMU, and machine learning algorithms","volume":"2021","author":"Kumar","year":"2021","journal-title":"Des. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Wesely, S., Hofer, E., Curth, R., Paryani, S., Mills, N., Uebersch\u00e4r, O., and Westermayr, J. (2025). Artificial Intelligence for Objective Assessment of Acrobatic Movements: Applying Machine Learning for Identifying Tumbling Elements in Cheer Sports. Sensors, 25.","DOI":"10.20944\/preprints202502.1406.v1"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Gorges, T., Davidson, P., Boeschen, M., Hotho, A., and Merz, C. (2024). IMU airtime detection in snowboard halfpipe: U-Net deep learning approach outperforms traditional threshold algorithms. Sensors, 24.","DOI":"10.3390\/s24216773"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Groh, B.H., Fleckenstein, M., and Eskofier, B.M. (2016, January 14\u201317). Wearable trick classification in freestyle snowboarding. Proceedings of the IEEE 13th International Conference on Wearable and Implantable Body Sensor Networks (BSN), San Francisco, CA, USA.","DOI":"10.1109\/BSN.2016.7516238"},{"key":"ref_15","unstructured":"Groh, B.H., Kautz, T., Schuldhaus, D., and Eskofier, B.M. (2015, January 10\u201313). IMU-based trick classification in skateboarding. Proceedings of the 21st ACM SIGKDD Conference on Knowledge Discovery and Data Mining, Sydney, Australia."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1590\/2446-4740.04717","article-title":"Development of a skateboarding trick classifier using accelerometry and machine learning","volume":"33","author":"Russomano","year":"2017","journal-title":"Res. Biomed. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Abdullah, M.A., Ibrahim, M.A.R., Shapiee, M.N.A.B., Mohd Razman, M.A., Musa, R.M., and Abdul Majeed, A.P.P. (2020). The classification of skateboarding trick manoeuvres through the integration of IMU and machine learning. Intelligent Manufacturing and Mechatronics (SympoSIMM 2019), Springer.","DOI":"10.1007\/978-981-13-9539-0_7"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e680","DOI":"10.7717\/peerj-cs.680","article-title":"The classification of skateboarding tricks via transfer learning pipelines","volume":"7","author":"Abdullah","year":"2021","journal-title":"PeerJ Comput. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.pmcj.2017.05.007","article-title":"Classification and visualization of skateboard tricks using wearable sensors","volume":"40","author":"Groh","year":"2017","journal-title":"Pervasive Mob. Comput."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Hassan, M.H.A., Muhamed, A.M.C., Mohd Ali, N.F., Choon Lian, D.K., Yee, K.L., Safii, N.S., Yusof, S.M., and Mohamad Fauzi, N.F. (2020). The Classification of Skateboarding Trick Manoeuvres: AK-Nearest Neighbour Approach. Enhancing Health and Sports Performance by Design (MoHE 2019), Springer.","DOI":"10.1007\/978-981-15-3270-2"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2006","DOI":"10.1080\/14763141.2021.1990384","article-title":"Automatic temporal event detection of the Ollie movement during skateboarding using wearable IMUs","volume":"23","author":"Hu","year":"2024","journal-title":"Sports Biomech."},{"key":"ref_22","first-page":"17543371221110424","article-title":"Test-retest reliability of customised inertial measurement units (IMUs) in evaluating skateboarding related manoeuvres","volume":"239","author":"Musa","year":"2022","journal-title":"Proc. Inst. Mech. Eng. Part P J. Sports Eng. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"807","DOI":"10.1007\/s001120170107","article-title":"Perzentile f\u00fcr den Body-mass-Index f\u00fcr das Kindes- und Jugendalter unter Heranziehung verschiedener deutscher Stichproben","volume":"149","author":"Wabitsch","year":"2001","journal-title":"Monatsschr. Kinderheilkd."},{"key":"ref_24","unstructured":"Spinnax GmbH (2025, November 04). Spinnax-der Skateboard Tracker. Available online: https:\/\/www.spinnax.com\/sensor\/."},{"key":"ref_25","unstructured":"Skatedeluxe GmbH (2025, July 24). The National May Marius 8.125\u2033 Skateboard Deck (Multi). Available online: https:\/\/www.skatedeluxe.com."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1519\/JSC.0b013e3181ccb18d","article-title":"Validity and reliability of Optojump photoelectric cells for estimating vertical jump height","volume":"25","author":"Glatthorn","year":"2011","journal-title":"J. Strength Cond. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"761","DOI":"10.1519\/JSC.0b013e31825dbcc5","article-title":"Concurrent validity of vertical jump performance assessment systems","volume":"27","author":"Castagna","year":"2013","journal-title":"J. Strength Cond. Res."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Villalon-Gasch, L., Penichet-Tomas, A., Olaya-Cuartero, J., and Jimenez-Olmedo, J.M. (2023). Criterion Validity and Reliability of the Compact Infrared-Based Photocell ADR Jumping to Estimate Vertical Jump. Appl. Sci., 13.","DOI":"10.3390\/app13053151"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Khemiri, A., Negra, Y., Ceylan, H.\u0130., Hajri, M., Njah, A., Hachana, Y., Y\u0131ld\u0131z, M., Bayrakdaro\u011flu, S., Muntean, R.I., and Attia, A. (2025). Concurrent Validity of the Optojump Infrared Photocell System in Lower Limb Peak Power Assessment: Comparative Analysis with the Wingate Anaerobic Test and Sprint Performance. Appl. Sci., 15.","DOI":"10.3390\/app151910741"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"\u0160tuhec, S., Planj\u0161ek, P., Ptak, M., \u010coh, M., and Mackala, K. (2022). Application of the Laser Linear Distance-Speed-Acceleration Measurement System and Sport Kinematic Analysis Software. Sensors, 22.","DOI":"10.3390\/s22155876"},{"key":"ref_31","unstructured":"Lehmann, T., Naundorf, F., Seemann-Sinn, A., and Kerner, S. (2023). Long-Term Development of Run-Up Velocity on Vault in Artistic Gymnastics, Steinbeis-Edition."},{"key":"ref_32","first-page":"33","article-title":"Biomechanics of skateboarding: Kinetics of the Ollie","volume":"22","author":"Frederick","year":"2006","journal-title":"J. Appl. Biomech."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"21-00230","DOI":"10.1299\/mej.21-00230","article-title":"Simulation study to elucidate the mechanism of ollie jump in skateboarding","volume":"8","author":"Nakashima","year":"2021","journal-title":"Mech. Eng. J."},{"key":"ref_34","unstructured":"Carlisle, J., Hammer, K., Hingtgen, R., and Martins, G. (2021). Skateboard Tricks and Topological Flips. arXiv."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1590\/S1980-65742014000300009","article-title":"Vertical jump fatigue does not affect intersegmental coordination and segmental contribution","volume":"20","author":"Pereira","year":"2014","journal-title":"Motriz Rev. Educ. Fis."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Stoer, J., and Bulirsch, R. (1992). Introduction to Numerical Analysis, Springer. [2nd ed.].","DOI":"10.1007\/978-1-4757-2272-7"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"113144","DOI":"10.1016\/j.physbeh.2020.113144","article-title":"Validity, reliability and usefulness of smartphone and kinovea motion analysis software for direct measurement of vertical jump height","volume":"227","author":"Pueo","year":"2020","journal-title":"Physiol. Behav."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"12097","DOI":"10.1088\/1757-899X\/342\/1\/012097","article-title":"Biomechanical analysis using Kinovea for sports application","volume":"342","author":"Lee","year":"2018","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_39","unstructured":"Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences, Lawrence Erlbaum Associates Publishers. [2nd ed.]."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/S0140-6736(86)90837-8","article-title":"Statistical methods for assessing agreement between two methods of clinical measurement","volume":"1","author":"Bland","year":"1986","journal-title":"Lancet"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"310","DOI":"10.3758\/s13428-011-0071-2","article-title":"Missing data imputation and corrected statistics for large-scale behavioral databases","volume":"43","author":"Courrieu","year":"2011","journal-title":"Behav. Res. Methods"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.jcm.2016.02.012","article-title":"A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research","volume":"15","author":"Koo","year":"2016","journal-title":"J. Chiropr. Med."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"961","DOI":"10.1080\/14763141.2021.1910334","article-title":"Machine learning in sports science: Challenges and opportunities","volume":"23","author":"Richter","year":"2024","journal-title":"Sports Biomech."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"454","DOI":"10.1007\/s12662-019-00581-6","article-title":"Zur Bestimmung der K\u00f6rperschwerpunkth\u00f6he bei Vertikalspr\u00fcngen","volume":"49","author":"Wank","year":"2019","journal-title":"Ger. J. Exerc. Sport Res."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/8\/2537\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T13:24:12Z","timestamp":1776691452000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/8\/2537"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,20]]},"references-count":44,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["s26082537"],"URL":"https:\/\/doi.org\/10.3390\/s26082537","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,20]]}}}