# Validation of Inertial Measurement Units and Force Plates in Measuring Jump Height during a Counter Movement Jump

Iris Willaert, Alix Renaud-Roy, Kevin Roux, Julien Clément

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Iris Willaert, Alix Renaud-Roy, Kevin Roux, Julien Clément. Validation of Inertial Measurement Units and Force Plates in Measuring Jump Height during a Counter Movement Jump. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16169. hal-05191721v2

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# Validation of Inertial Measurement Units and Force Plates in Measuring Jump Height during a Counter Movement Jump

Iris Willaert<sup>a</sup>, Alix Renaud-Roy<sup>b</sup>, Kevin Roux<sup>b</sup>, Julien Clément<sup>a, b*</sup>

<sup>a</sup> École de technologie supérieure, Montréal (ÉTS), Canada

<sup>b</sup> Institut National du Sport du Québec, Montréal, Canada

* Corresponding author: julien.clement@etsmtl.ca

Received date: 03/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** IMU, sport performance, jump height, countermovement, wearable sensors

© 2025 The Authors
Licence CC-BY 4.0
Published by Société de Biomécanique

## 1. Introduction

Countermovement jumps (CMJs) are widely used to assess lower limb strength and neuromuscular fatigue in athletes (Gathercole et al., 2013). Metrics derived from CMJs, such as jump height, flight time, and peak velocity, are essential for assessing sport-specific performance (Anicic et al., 2023). Traditionally, force plates have been employed to measure these metrics during CMJs due to their high accuracy and reliability. However, their lack of portability limits their use in competition venues or field settings. Wearable sensors, particularly Inertial Measurement Units (IMUs), have emerged as viable alternatives, offering greater portability and affordability. Numerous studies have demonstrated that IMUs can accurately estimate jump-related metrics such as jump height (MacDonald et al., 2017). Commercially available devices such as Enode Pro (Blaumann & Meyer-Sports Technology UG, Germany) and Output Sport (Output Sports, Ireland) have gained popularity to measure CMJs metrics. But despite a strong correlation with 3D motion capture (MoCAP) systems, the Enode Pro consistently underestimated jump height during CMJs (Puljic et al. 2024). Similarly, the Output Sports sensor showed only acceptable validity for jump height assessment compared to reference systems (Comyns et al., 2023). This study aims to confirm these results by comparing the accuracy and sensitivity of the two IMUs in measuring CMJ height and validate them against a gold-standard motion capture system.

## 2. Methods

Twenty-nine elite speed skaters (15 males, 14 females) participated in this study. Inclusion criteria required absence of lower-limb injuries and unrestricted gym training capacity. Ethical approval was granted by ÉTS, and written consent was obtained. The experiment lasted a total of 10 minutes. The Enode Pro (1000 Hz) was taped on a waistband (placed on the lower back L4-L5) and the Output Sports sensor (1024 Hz) was taped on top of the right foot per manufactures instructions. Reference measurements were obtained using a Polaris Spectra optical system (60 Hz) tracking a rigid body on the waistband, along with two force plates: a stationary AMTI (1000 Hz) and a portable PASCO (1000 Hz) plate stacked for concurrent data collection. A Panasonic high-speed video camera (60 Hz) was used to capture the moment of take-off during each jump. Each athlete performed five consecutive CMJs with their hands placed on their hips. Jump height was calculated as the difference between take-off and peak vertical position of the rigid body. In addition to intraclass correlation coefficients (ICC) for reliability, the smallest worthwhile change (SWC) and typical error (TE) were calculated to assess each device's sensitivity, with SWC/TE ratios greater than 1 indicating sufficient sensitivity to detect meaningful performance changes. A Linear Mixed Model (LMM) was used to evaluate differences in jump height across various devices, with the Polaris Spectra set as the reference level.
## 3. Results and discussion

An overview of the results can be found in Table 1. Figure 1 presents Bland-Altman plots comparing Enode Pro and Output Sports to the Polaris Spectra, illustrating measurement bias and variability for each device. The LMM revealed a significant main effect for the Enode Pro device on jump height (SE = 0.55, t(686) = 10.92, p = 0.001) compared to the Polaris Spectra. In contrast, no significant differences were observed for the Output Sports (Standard Error (SE) = 0.55, t(686) = -1.89, p = 0.058), PASCO (SE = 0.55, t(686) = 0.06, p = 0.98), or AMTI (SE = 0.55, t(686) = -0.29, p = 0.99). Both force plates provided accurate estimates of jump height and sensitivity relative to the reference system.

The Enode Pro demonstrated good reliability (ICC = 0.96), consistent with previous findings (Puljic et al., 2024). However, it significantly overestimated jump height compared to the Polaris Spectra. It demonstrated a SWC of 1.41 cm and a TE of 1.76 cm (SWC/TE = 0.80), suggesting limited sensitivity to detect small but meaningful changes in jump height. The Output Sports sensor also showed acceptable reliability (ICC = 0.80), but failed to register certain CMJs, resulting in missing data. It showed an SWC of 1.78 cm and a TE of 3.88 cm (SWC/TE = 0.46), further indicating limited sensitivity. In addition, it exhibited a much higher standard deviation (±13.27 cm) than other devices (±6.5–7.2 cm), indicating greater measurement variability. This contrasts with previous findings (Comyns et al., 2023), which reported no such inconsistencies and acceptable validity for jump height assessment. The CMJs were performed with a natural technique with the sensor placed on the foot (manufacturer's guidelines), which may have introduced greater foot motion variability, contributing to greater variability and reduced accuracy.

<table><caption>**Table 1.** Jump height analysis across devices.</caption><thead><tr><th>Device</th><th>Jump height (cm)</th><th>ICC</th><th>SWC (cm)</th><th>TE</th><th>SWC/TE</th></tr></thead><tbody><tr><td>Polaris Spectra</td><td>38.22 (± 6.80)</td><td>0.99</td><td>1.38</td><td>1.21</td><td>1.14</td></tr><tr><td>Enode Pro</td><td>44.28 (± 7.20) †</td><td>0.96</td><td>1.41</td><td>1.76</td><td>0.80</td></tr><tr><td>Output Sports</td><td>35.22 (± 13.27)</td><td>0.80</td><td>1.78</td><td>3.88</td><td>0.46</td></tr><tr><td>PASCO</td><td>38.30 (± 6.60)</td><td>0.99</td><td>1.37</td><td>0.96</td><td>1.44</td></tr><tr><td>AMTI</td><td>38.08 (± 6.72)</td><td>0.98</td><td>1.36</td><td>1.05</td><td>1.29</td></tr></tbody></table>

† means significant difference compared to the Polaris spectra p<0.05.

<figure><img src="image_3.png" /><figcaption>**Figure 1.** Bland-Altman plots comparing Enode Pro (A) and Output Sports (B) to Polaris Spectra.</figcaption></figure>

## 4. Conclusions

While both IMUs offer practical advantages in terms of portability and ease of use, their performance in this study highlights insufficient sensitivity to detect meaningful changes in performance. These findings question the reliability of both devices for field application, especially in elite sport settings where even a 1 cm difference can be meaningful.

## Acknowledgements

The authors would like to thank Short Track Speed Skating Team Canada for their availability.

## Conflict of Interest Statement

None.

## Contributor Roles

IW: Methodology, Data analysis, Writing original draft; KR: Project administration, Data curation, Supervision; ARR: Project administration, Data curation, Supervision; JC: Methodology, Funding acquisition, Supervision, Validation, Writing-review & editing.

## Funding

This work was funded by the Research, Innovation and Dissemination Program of the Institut national du sport du Québec (Montréal, QC, Canada).

## References

Anicic, Z., Janicijevic, D., Knezevic, O. M., Garcia-Ramos, A., Petrovic, M. R., Cabarkapa, D., & Mirkov, D. M. (2023). Assessment of countermovement jump: What should we report? *Life, 13*(1), 190. https://doi.org/10.3390/life13010190
Comyns, T. M., Murphy, J., & O'Leary, D. (2023). Reliability, usefulness, and validity of field-based vertical jump measuring devices. *The Journal of Strength & Conditioning Research*, 37, 1594. https://doi.org/10.1519/JSC.0000000000004436

Gathercole, R., Sporer, B., Stellingwerff, T., & Sleivert, G. (2015). Alternative countermovement-jump analysis to quantify acute neuromuscular fatigue. *International Journal of Sports Physiology and Performance*, 10, 84–92. https://doi.org/10.1123/ijspp.2013-0413

MacDonald, K., Bahr, R., Baltich, J., Whittaker, J. L., & Meeuwisse, W. H. (2017). Validation of an inertial measurement unit for the measurement of jump count and height. *Physical Therapy in Sport*, 25, 15–19. https://doi.org/10.1016/j.ptsp.2016.12.1001

Puljić, D., Karavas, C., Mandroukas, A., & Stafylidis, A. (2024). Validity of the Enode Sensor and My Jump 3 App for assessing countermovement jump performance. *Applied Sciences*, 14(24), 11989. https://doi.org/10.3390/app142411989