# Rein tensions and stirrup forces in horse riding: new reference values based on a large database

Eléna Pycik, Sophie Biau, Benoit Pasquiet, Agnès Olivier

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Eléna Pycik, Sophie Biau, Benoit Pasquiet, Agnès Olivier. Rein tensions and stirrup forces in horse riding: new reference values based on a large database. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16181. hal-05191733v2

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# Rein tensions and stirrup forces in horse riding: new reference values based on a large database

Eléna Pycik*, Sophie Biau, Benoit Pasquiet, Agnès Olivier

Institut Français du Cheval et de l'Equitation, Plateau technique de Saumur,
Saumur, France

* Corresponding author: elena.pycik@ifce.fr

Received date: 04/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** horse-rider, database, rein tensions, stirrup forces

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

## 1. Introduction

In horse riding, riders communicate with horses through aids: hands, legs and seat. It is possible to evaluate the aids through rein tensions and stirrup forces.

According to a review (Dumbell et al., 2018), rein tensions range from 6.9 to 43 N at walk, 10.8 to 51 N at trot and 1.5 to 104 N at canter. Studies show high variability and a lack of consistency in participants, tools and treatments description. Stirrup forces are less studied but the same applies. Marlin et al. (2022) were the first to study both rein tensions and stirrup forces at multiple gaits in advanced level riders (n=8).

Small-scale studies are common in equestrian research due to the difficulty of accessing horses and riders managed under the same conditions, at the risk of overestimating an effect (Hackshaw, 2008). Larger-scale studies are needed to explore the factors contributing to aids variability, linked to the rider (sex, weight, height, level, laterality), the horse (sex, genetics, level) and the performance (gait, movement, tack).

This study aims to describe rein tensions and stirrup forces at different gaits with a large database collected on hundred experienced horses and riders in the context of sport performance analysis, including all assumed influencing factors. Further analysis could examine the link between symmetry and rider laterality, how this varies with expertise, or any potential sex differences.

## 2. Methods

### 2.1 Population

The database includes 271 experienced horse-rider pairs (amateur 2 level and higher).

### 2.2 Acquisition system

Rein tensions and normal stirrup forces were recorded at 256 Hz by transducers and acquisition boxes (Shimmer3 Bridge Amplifier+ Unit, Shimmer Sensing, Ireland), integrated on a composite material in the rein or into the stirrup arm as described by (Biau et al., 2024).

### 2.3 Protocol

Most of the pairs performed filmed straight lines either on the track or on the middle line of the arena at medium walk, working trot (rising and sitting), working left and right canter (normal seat and forward seat).

### 2.4 Treatment

Exclusion criteria removed pairs who: (1) did not perform straight lines; (2) did not wear a general-purpose saddle and a snaffle bridle; (3) appeared more than once, or whose horse or rider appeared individually more than three times.

25 meters straight lines were identified in the video. One passage per pair at each gait was analysed with Matlab and R software. Mean±SD and 25th, 50th and 75th quartiles of mean and coefficient of variation (CoV) rein tensions and stirrup forces were examined according to left-right side (Wilcoxon test) per gait.
<table><caption>**Table 1.** Mean rein tensions (N) and stirrup forces (N/kg), and CoV (%), at each gait.</caption><thead><tr><th></th><th>Gait</th><th>LR</th><th>RR</th><th>LS</th><th>RS</th></tr></thead><tbody><tr><td rowspan="10">Mean</td><td rowspan="2">W</td><td>8±4</td><td>8±4</td><td>1.0±0.3</td><td>1.3±0.5</td></tr><tr><td>5,8,10</td><td>6,8,10</td><td>0.8,1.0,1.3</td><td>1.0,1.2,1.5</td></tr><tr><td rowspan="2">RT</td><td>12±6</td><td>13±6</td><td>2.3±0.4</td><td>2.5±0.5</td></tr><tr><td>8,11,15</td><td>9,12,16</td><td>2.1,2.3,2.5</td><td>2.2,2.5,2.7</td></tr><tr><td rowspan="2">ST</td><td>16±7</td><td>16±8</td><td>1.2±0.3</td><td>1.3±0.4</td></tr><tr><td>10,16,20</td><td>10,14,20</td><td>0.9,1.1,1.4</td><td>1.0,1.2,1.5</td></tr><tr><td rowspan="2">nRC</td><td>20±10</td><td>21±9</td><td>1.8±0.5</td><td>1.8±0.7</td></tr><tr><td>13,19,24</td><td>14,20,27</td><td>1.4,1.8,2.0</td><td>1.4,1.8,2.2</td></tr><tr><td rowspan="2">nLC</td><td>20±9</td><td>20±9</td><td>1.7±0.5</td><td>2.1±0.8</td></tr><tr><td>13,18,26</td><td>14,19,26</td><td>1.4,1.6,2.0</td><td>1.5,2.0,2.4</td></tr><tr><td rowspan="2">fRC</td><td>19±12</td><td>18±10</td><td>3.9±0.8</td><td>3.7±0.8</td></tr><tr><td>10,15,22</td><td>11,16,26</td><td>3.3,3.9,4.3</td><td>3.1,3.5,4.1</td></tr><tr><td rowspan="2">fLC</td><td>18±9</td><td>17±8</td><td>3.4±0.7</td><td>4.2±0.9</td></tr><tr><td>11,17,22</td><td>11,16,22</td><td>3.0,3.4,3.8</td><td>3.6,4.2,4.6</td></tr><tr><td rowspan="10">CoV</td><td rowspan="2">W</td><td>75±49</td><td>65±21</td><td>32±18</td><td>28±18</td></tr><tr><td>55,68,80</td><td>53,62,72</td><td>23,29,36</td><td>19,26,33</td></tr><tr><td rowspan="2">RT</td><td>69±23</td><td>64±16</td><td>92±17</td><td>89±17</td></tr><tr><td>54,67,78</td><td>54,62,73</td><td>81,92,103</td><td>78,89,101</td></tr><tr><td rowspan="2">ST</td><td>68±18</td><td>66±15</td><td>75±14</td><td>74±14</td></tr><tr><td>56,67,76</td><td>55,64,77</td><td>66,74,81</td><td>63,77,82</td></tr><tr><td rowspan="2">nRC</td><td>80±22</td><td>72±16</td><td>67±12</td><td>63±13</td></tr><tr><td>65,78,93</td><td>61,70,82</td><td>59,67,74</td><td>55,63,72</td></tr><tr><td rowspan="2">nLC</td><td>76±19</td><td>75±16</td><td>62±11</td><td>65±15</td></tr><tr><td>63,74,89</td><td>63,77,87</td><td>54,61,70</td><td>55,65,77</td></tr><tr><td rowspan="2">fRC</td><td>73±24</td><td>71±26</td><td>76±14</td><td>70±16</td></tr><tr><td>56,71,86</td><td>54,68,83</td><td>67,75,86</td><td>60,67,75</td></tr><tr><td rowspan="2">fLC</td><td>70±23</td><td>75±25</td><td>67±14</td><td>79±14</td></tr><tr><td>52,68,82</td><td>57,71,86</td><td>58,65,74</td><td>71,80,87</td></tr></tbody></table>

Mean±SD and 25th, 50th and 75th quartiles of mean and CoV for rein tensions and stirrup forces are presented. W=Walk, RT/ST=rising/sitting trot, nRC/nLC=normal seat right/left canter, fRC/fLC=forward seat right/left canter, LR/RR=left/right rein, LS/RS=left/right stirrup.

### 3. Results and discussion

128 pairs were included in the analysis (Fig. 1): 101 riders (62±9 kg, 170±8 cm, 24±7 years, 68 women/33 men) and 110 horses.

Data are shown in Table 1. Mean rein tensions align with literature, increasing from walk to canter. CoV offers a new insight for rein tensions consistency, with mean values in the range of 59.8-118.8% (Bohara et al., 2023). Mean and CoV rein tensions at walk, rising trot and normal seat right canter show significant left-right differences (p<0.05) with higher tension in the right rein and higher CoV in the left.

Mean and CoV stirrup forces show significant left-right differences (p<0.05). At walk and trot, mean values are higher in the right stirrup and CoV in the left (except for sitting trot, no CoV difference). At canter, both values are higher on the external stirrup (except for normal seat right canter, no mean difference).

This initial description of the database show left-right differences. As the database contains metadata on the horse, the rider and the performance, as well as kinematics data (not presented here), these differences will be further analysed in relation to symmetry indices. In the longer term, this kind of aids analysis could lead to improvements in training, tack development or health prevention.

<figure><img src="image_2.png" /><figcaption>**Figure 1.** Measure selection flow chart.</figcaption></figure>
## 4. Conclusions

The originality of our study is the acquisition of reference values (rein tensions and stirrup forces) from a large and expert database at different gaits in the context of sport performance analysis. Left-right differences per gait are present but the database will enable new large-scale aids analysis to better understand horse-rider interaction.

## Conflict of Interest Statement

None.

## Contributor Roles

EP: Investigation, Data curation, Formal analysis, Software, Writing – original draft. SB: Conceptualization, Supervision, Methodology, Writing – review & editing. BP: Software, Writing – review & editing. AO: Conceptualization, Project administration, Supervision, Writing – review & editing.

## Funding

We thank Institut Français du Cheval et de l'Equitation for funding.

## References

* Biau, S., Leblanc, M., Pycik, E., Pasquiet, B., & Huet, B. (2024). Biomechanical characterization of preparation for airs above the ground: A mixed approach. *Animals*, *14*(189), 1–16. https://doi.org/10.3390/ani14020189

* Bohara, G., Lancaster, B., & Randle, H. (2023). The effect of elastic reins on rein tension and performance in dressage horses. *Journal of Veterinary Behavior, 59*, 53–66. https://doi.org/10.1016/j.jveb.2022.11.012

* Dumbell, L., Lemon, C., & Williams, J. (2018). A systematic literature review to evaluate the tools and methods used to measure rein tension. *Journal of Veterinary Behavior, 29*, 77–87. https://doi.org/10.1016/j.jveb.2018.04.003

* Hackshaw, A. (2008). Small studies: Strengths and limitations. *European Respiratory Journal, 32*(5), 1141–1143. https://doi.org/10.1183/09031936.00136408

* Marlin, D. J., Fisher, M., Fisher, D., & Mackechnie-Guire, R. (2022). Stirrup and rein forces do not show left-right differences in advanced dressage riders and horses. 11th International Conference on Equine Exercise Physiology, Uppsala, Sweden. *Comparative Exercise Physiology, 18*(6), 81. https://doi.org/10.3920/cep2022.s1