# Validation of a pole with a force sensor for field studies on Nordic walking

Constance Bisson, Alexandre Adjimi, Khaireddine Ben Mansour, Nasser

Rezzoug

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Constance Bisson, Alexandre Adjimi, Khaireddine Ben Mansour, Nasser Rezzoug. Validation of a pole with a force sensor for field studies on Nordic walking. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16188 . hal-05191740v2

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# Validation of a pole with a force sensor for field studies on Nordic walking

Constance Bissonª, Alexandre Adjimiª,
Khaireddine Ben Mansourᵇ, Nasser Rezzougª*

ª Institut Pprime (Université de Poitiers, CNRS, ISAE-ENSMA), UPR 3346, Poitiers, France

ᵇ Université de Lorraine, DevAH, Nancy, France

* Corresponding author: nasser.rezzoug@univ-poitiers.fr

Received date: 06/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** Nordic walking, force sensor, validation

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

## 1. Introduction

Nordic walking is a popular activity involving a substantial contribution of the upper-limbs due to the use of poles. Studies have demonstrated its physiological, and motor benefits for healthy as well as patients with cancer, depression, obesity or Parkinson disease (Fritschi et al., 2012). To date, there is no consensus on the biomechanics of this activity concerning both spatio-temporal parameters, joint kinematics and loads sharing between the upper and lower limbs (Jensen et al., 2011). Moreover, the vast majority of studies consider laboratory settings which do not reflect field conditions (Ben Mansour et al., 2018). Therefore, the biomechanics of Nordic walking and especially the joint loads on the upper-limb still need to be assessed more thoroughly. To this goal, the use of instrumented poles to record applied forces is mandatory (Lesaffre et al., 2025; Spazla et al., 2024). In this framework, the aim of this study is to validate the data obtained from an instrumented pole with a force sensor in comparison to force platform data in a laboratory setting.

## 2. Methods

### 2.1 Materials

An instrumented pole designed in collaboration with a local manufacturer is used. It is equipped with strain gauges embedded in a test body placed below the pole handle. Force exerted in the longitudinal axis of the pole (Fz) and moments in the transverse plane (Mx and My)

are measured. The force sensor was calibrated by the manufacturer. The pole is also equipped with an IMU that provides its orientation. The sampling rate is 100Hz. The data are transmitted to a receiver via Bluetooth which sends data to a laptop via a USB link. An interface is provided to configure the sensor parameters and manage the data acquisition process. A force platform (Bertec) provides force reference data at 1000Hz down-sampled to 100 Hz. In this study, the IMU is not considered to provide the pole orientation. Instead, a 3 retroreflective markers 3D printed cluster is placed on the pole. An optoelectronic system (Qualisys) defines the reference frames of the pole and the force platform. Both force signals are synchronized by using cross-correlation. The force platform data were projected in the pole reference frame allowing a direct comparison of the Fz forces. No filtering procedure was applied.

### 2.2 Trials description

Static trials consisted in positioning the pole either vertically or at an angle of approximately 30°, followed by the application of a series of five exertions. Each trial was done with and without the rubber tip guard of the pole to assess its effect on the measured forces. Dynamic trials consisted of measuring the applied forces during simulated Nordic walking steps during which the participant took one step forward and then stepped back to take another step forward. This was repeated five times. For each condition 3 to 5 trials were recorded on one participant.
## 2.3 Validation procedure

In order to assess the agreement between both systems, a Bland-Altman procedure was used and systematic bias and limits of agreements were computed. In addition, the coefficient of correlation, the slope and the intercept of the linear regression between both data was computed. These different indicators were averaged for each condition.

## 3. Results and discussion

An example of force recordings for each trial types (static vertical and tilted and gait trial) is presented in Fig.1. Table 1 provides results on the slope, correlation coefficient, bias and limits of agreement from the Bland Altman procedure. The slope of the linear relationship is close to one as well as the correlation coefficient (the p value of the correlation coefficient and the intercept not presented here are almost equal to 0). The maximum bias is 2.54N, the minimum limit of agreement is -6.82N and the maximum is 11.85N. Globally the bias is 0.93N and the lower and upper limits of agreement are -5.15N and 7.01N. In addition, the Bland and Altman plots did not show dependency of the bias on the force amplitudes. These results indicate that the forces measured by the sensor in the pole and those from the force platform are in close agreement.

The greatest biases were obtained during the gait and static trials with a tilted pole and rubber tip guard. These discrepancies may result from force exertion on an inclined pole, which may generate forces orthogonal to the pole's axis, especially when the rubber tip guard is present, as it enables frictional forces.

## 4. Conclusions

The aim of the present work was to validate an instrumented pole with a force sensor to evaluate Nordic walking in field conditions. The results indicate that the data from the pole are in close agreement with those of force platform considered as the gold standard. Future work will focus on validating the data coming from the IMU to allow in field evaluation. Also, the long-term reliability and the effect of ground nature on recorded forces will be investigated.

<figure><img src="image_2.png" /><figcaption>**Figure 1.** Comparison between the force platform and the pole sensor. a. static trial with a vertical pole, b. static trial with tilted pole, c. Simulated Nordic walking trial.</figcaption></figure>

<table><caption>**Table 1.** Validation results for gait and static trials.</caption><thead><tr><th>Trial</th><th>Slope</th><th>R</th><th>Bias</th><th>Lower limit</th><th>Upper limit</th></tr></thead><tbody><tr><td>Gait</td><td>1.081</td><td>0.9936</td><td>0.92</td><td>-6.82</td><td>8.66</td></tr><tr><td>Static</td><td>1.035</td><td>0.9996</td><td>0.94</td><td>-4.45</td><td>6.33</td></tr><tr><td>Tilted</td><td>1.073</td><td>0.9995</td><td>1.89</td><td>-5.47</td><td>9.26</td></tr><tr><td>With tip guard</td><td>1.096</td><td>0.9995</td><td>2.54</td><td>-6.78</td><td>11.85</td></tr></tbody></table>
<table><thead><tr><th>Trial</th><th>Slope</th><th>R</th><th>Bias</th><th>Lower limit</th><th>Upper limit</th></tr></thead><tbody><tr><td>W/o tip guard</td><td>1.050</td><td>0.9996</td><td>1.25</td><td>-4.16</td><td>6.66</td></tr><tr><td>Vertical</td><td>0.997</td><td>0.9996</td><td>-0.02</td><td>-3.44</td><td>3.40</td></tr><tr><td>With tip guard</td><td>1.012</td><td>0.9996</td><td>0.46</td><td>-3.03</td><td>3.96</td></tr><tr><td>W/o tip guard</td><td>0.982</td><td>0.9996</td><td>-0.50</td><td>-3.85</td><td>2.84</td></tr><tr><td>Global results</td><td>1.048</td><td>0.9978</td><td>0.93</td><td>-5.15</td><td>7.01</td></tr></tbody></table>

Underlined results are global. For static trials the mean results are separated in two parts, vertical and tilted pole. Values in italic correspond to the detail of the results with and without tip guard for the vertical and tilted conditions. Bias and limits of agreement are expressed in Newtons.

## Acknowledgements

We wish to thank Arnaud Decatoire, for his aid on the experimental set-up and Romain Tisserand for the Bertec Force-Platform.

## Conflict of Interest Statement

None

## Contributor Roles

CB, AA: Methodology, Data curation, Formal analysis, Software; KBM: Conceptualization, Review & editing; NR: Conceptualization, Methodology, Writing original draft, Funding acquisition, Validation & Supervision.

## Funding

This research was funded by the Nouvelle Aquitaine Regional Council (P-2020-BAFE161), in partnership with the European Union (FEDER/ERDF) and by the Pprime institute.

## References

* Ben Mansour, K., Gorce, P., & Rezzoug, N. (2018). The impact of Nordic walking training on the gait of the elderly. *Journal of Sports Sciences*, 36(20), 2368-2374. https://doi.org/10.1080/02640414.2018.1458396

* Fritschi, J. O., Brown, W. J., Laukkanen, R., & Van Uffelen, J. G. Z. (2012). The effects of pole walking on health in adults: A systematic review. *Scandinavian Journal of Medicine & Science in Sports*, 22(5). https://doi.org/10.1111/j.1600-0838.2012.01495.x

* Jensen, S. B., Henriksen, M., Aaboe, J., Hansen, L., Simonsen, E. B., & Alkjær, T. (2011). Is it possible to reduce the knee joint compression force during level walking with hiking poles? *Scandinavian Journal of Medicine & Science in Sports*, 21(6). https://doi.org/10.1111/j.1600-0838.2010.01241.x

* Lesaffre, R., Wallard, L., Henry, P., & Blandeau, M. (2025). Validation of on-board algorithms for detecting walking events during Nordic walking. *Multidisciplinary Biomechanics Journal*, 1, 427-429. https://doi.org/10.46298/mbj.14559

* Szpala, A., Winiarski, S., Kołodziej, M. Jasiński, R., Lejczak, A., Kałka, D., Lorek, K., Bałchanowski, J., Wudarczyk, S., Woźniewski, & M. Pietraszewski, B. (2024) Effects of nordic walking training on gait and exercise tolerance in male ischemic heart disease patients. *Sci Rep*, 14, 11249. https://doi.org/10.1038/s41598-024-62109-9