# Balance control mechanisms during hanstands

Thomas Robert, Charlotte Le Mouel, Romain Tisserand

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Thomas Robert, Charlotte Le Mouel, Romain Tisserand. Balance control mechanisms during hanstands. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the., 10.46298/mbj.16214. hal-05191768v2

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Submitted on 23 Oct 2025

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# Balance control mechanisms during hanstands

Thomas Robert<sup>a*</sup>, Charlotte Le Mouel<sup>b</sup>,
Romain Tisserand<sup>c, d</sup>

<sup>a</sup> Univ Lyon, Univ Gustave Eiffel, Univ Claude Bernard Lyon 1, LBMC UMR_T 9406, F-69622 Lyon, France

<sup>b</sup> Sorbonne Université, CNRS, Institut des Systèmes Intelligents et de Robotique, ISIR, F-75005 Paris, France

<sup>c</sup> Université de Poitiers, ISAE-EN SMA, CNRS, PPrime, Poitiers, France

<sup>d</sup> Université de Poitiers, Université de Tours, CNRS, CeRCA, Poitiers, France

* Corresponding author: thomas.robert@univ-eiffel.fr

Received date: 06/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** balance control, handstand, center of pressure, angular momentum

© 2025 The Authors

Licence CC-BY 4.0

Published by Société de Biomécanique

## 1. Introduction

Balance control in standing posture has been widely studied. The majority of studies focused on balance control through the displacement of the center of pressure within the base of support (BoS). Still, balance can also be controlled through alternative mechanisms, such as regulating angular momentum. Hof (2007) introduced a method to quantify the respective contributions of the CoP and angular momentum regulation mechanisms in the overall balance control — the regulation of the whole-body center of mass (CoM) acceleration — during postural tasks. A recent study confirmed that, if the CoP regulation is the dominant strategy in bipedal quiet standing, the contribution of angular momentum regulation overcomes it in more challenging tasks (Tisserand, Plard, & Robert, 2023).

Hanstand resembles a standing posture but appears more challenging in terms of balance control. Several studies considered handstand balance control, but they primarily focused on statistical relations between local variables (joint angles or torques) and the CoM displacement. Results suggest that the regulation of wrist torque (i.e., of the CoP) is associated with successful balance control (Kerwin & Trewartha, 2001). Yet, the relative contributions of the CoP and angular momentum regulation strategies, and their association with successful balance control in handstand, remain to be clarified.

## 2. Methods

### 2.1 Data collection

After giving their informed consent, sixteen young subjects aged between 20 and 33 years participated in this experiment. They had a recreational practice of gymnastics at the university gymnastics association.

Participants were asked to perform multiple handstands during two trials of 3 minutes, and to hold them as long as possible, up to 30 seconds. Participant were free to adopt their preferred stance width (distance between hands). The trajectories of 45 reflective markers placed on anatomical landmarks were recorded using an optoelectronic system (18 cameras) sampling at 200 Hz. Ground reaction forces (GRF) were recorded using force plates sampling at 1000 Hz.

### 2.2 Data processing

The whole-body CoM was obtained using both kinematic data and GRF according to the methodology proposed by Le Mouel (2025). CoM acceleration and CoP were directly obtained from the GRF.

Foot-off and foot-landing, marking the onset and termination of handstands, were identified from ground reaction forces. The handstand was considered from 2 seconds after the foot-off to 2 seconds before the foot landing. The handstands were further analyzed only if they lasted more than 6 seconds. For this analysis, we used the handstand duration as performance criteria.
The CoM acceleration resulted from two contribu-
tions: 1) the regulation of the CoP position relative to the
CoM, and 2) the variation of the angular momentum
around the CoM. Considering the body as a linearized
inverted pendulum with an inertia wheel, the CoM accel-
eration induced by the first mechanisms was computed
as a proportion of the distance between the CoP and
the projection of the CoM on the ground (Hof, 2007).
The relative contribution of the CoP mechanism to the
CoM acceleration (% CoP) was then computed for each
handstand as the linear regression coefficient (Hof, 2007).

3. Results and discussion

Results are presented for the AP direction only. The
relative contributions of the CoP mechanism to the
CoM acceleration (% CoP) are displayed as functions
of the handstand duration in Figure 1.

<figure><img src="image_2.png" /><figcaption>Figure 1. Relative contributions of the CoP mechanism to the CoM acceleration (% CoP) in the AP direction as a function of the handstand duration: one dot per trial, one color per subject.</figcaption></figure>

Overall, relatively large values of %CoP were
observed, with an average of 82%. These are compa-
rable to those observed for quiet standing on both feet
(Tisserand et al., 2023). Yet, a large variability between
handstands can be observed, with participants who tend
to have specific strategies.

Still, high %CoP values seem related to performance:
the longer handstands tend to have a more significant
%CoP (average %CoP of 91% for handstands longer

than 25 seconds), and no trials with small %CoP were
observed for the longest handstands (> 25 seconds).

One may notice that %CoP is above 100% for sev-
eral handstands. Inaccuracies in data measurement
(notably the very small shear forces used to estimate
CoM accelerations) or in the modeling hypotheses
might play a role. Another explanation might come
from the challenging control of segment rotations
during handstands. As a result, angular momentum
variations might have a destabilizing action and act
in opposition to the CoP mechanisms. Such a situa-
tion, very rare in quiet standing, leads to an artificial
increase of the %CoP. This phenomenon would deserve
further investigation. Other limitations are the use of
handstand duration as a performance criterion, as it
is saturated by the instructions to stop the handstand
after about 30 seconds, and the fact that participants
had the same gymnastic background. It would be of
interest to investigate participants from other disciplines
(e.g., breakdance) to see if it might have an impact on
the use of balance control strategies during handstand.

4. Conclusions

This study provided a first estimate of the relative con-
tribution of both balance control mechanisms during
handstands. It confirmed that the regulation of the CoP
is the predominant strategy for the gymnast population
considered.

Conflict of Interest Statement

The authors declare no conflict of interest during this study.

Contributor Roles

TR: Conceptualization, Methodology, Writing original draft, Software; CML: Conceptualization, Funding acquisition, Conceptualization, Data curation, Methodology, Writing- review & editing; RT: Conceptualization, Methodology, Writing- review & editing.

References

Hof, A. L. (2007). The equations of motion for a stand-
ing human reveal three mechanisms for balance.
*Journal of Biomechanics, 40*(2), 451–457. https://doi.
org/10.1016/j.jbiomech.2005.12.016

Kerwin, D. G., & Trewartha, G. (2001). Strategies for maintaining a handstand in the anterior-posterior direction. *Medicine and Science in Sports*
and *Exercise*, 33(7), 1182–1188. https://doi.org/10.1097/00005768-200107000-00016

Le Mouel, C. (2025). Improved accuracy of the whole body Center of Mass position through Kalman filtering. *Peer Community Journal*, 5. https://doi.org/10.24072/pcjournal.510

Tisserand, R., Plard, J., & Robert, T. (2023). Relative contributions of postural balance mechanisms reveal studying the CoP displacement alone may be incomplete for analysis of challenging standing postures. *Gait & Posture, 101*, 134–137. https://doi.org/10.1016/j.gaitpost.2023.02.011