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# Investigating critical torque estimation in untrained participants

Antonin Le Corre, Nicolas A Turpin, Jérémie Begue, Antoine Mariani,

Nathan Caron, Georges Dalleau

► To cite this version:

Antonin Le Corre, Nicolas A Turpin, Jérémie Begue, Antoine Mariani, Nathan Caron, et al. Investigating critical torque estimation in untrained participants. 20ième congrès de l'ACAPS REIMS 2023, Oct 2023, REIMS, France. hal-04558519

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Submitted on 26 Apr 2024

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# Investigating critical torque estimation in untrained participants

Antonin Le Corre a, Nicolas A. Turpin a, Jérémie Begue a, Antoine Mariani a, Nathan Caron a, Georges Dalleau a
a Laboratoire IRISSE - EA 4075, UFR des Sciences de l'Homme et de l'Environnement, Université de La Réunion, 117 rue du Général Ailleret, 97430 Le Tampon, Île de La Réunion

## Introduction

During an all-out test, **peak torques decrease exponentially and reach a plateau called Critical Torque (CT)**, due to an accumulation of fatigue [1]. Both central and peripheral fatigue can be quantified by changes in Voluntary Activation level (VA%) and the Potentiated Torque amplitudes (PTa) [2, 3]. It has been shown that **PTa decrease exponentially during an all-out** [4] but, the plateau is not always **clearly identifiable**. We observed that **PTa could re-increase at the all-out end in some participants** (group A, fig.1) suggesting pacing strategies or neuromuscular recovery. While pacing strategies are difficult to prevent and biases CT estimation in untrained adults, it seems fundamental to **adjust CT estimation for these untrained participants**.

<figure><img src="image_1.png" /><figcaption>Figure 1</figcaption></figure>

**We aimed to test and compare different methods of estimating CT, to reduce estimation bias in untrained adults**

## Methods

* **34 untrained adults** performed an all-out test with the plantar flexors.

* Participants with an **extremum point** (fig.1) in **PTa kinetic** were **allocated to group A** (n=14; 31,21±9,69 yrs.) and **the others to group B** (37,70±14,20 yrs.).

* PTa and VA% were evaluated every 30s.

* Four critical torque (CT) estimation methods were compared:

* the **average of the last 30s** (CT<sub>end-test</sub>)

* the **asymptote of an exponential fit** (CT<sub>exp</sub>) in iMVCs kinetic

* the **minimum of a quadratic fit** (CT<sub>quad</sub>) in iMVCs kinetic

* a **method of extrapolation** (CT<sub>extrap</sub>) between the variations in PTa and the variations in iMVC (fig.2).

<figure><img src="image_2.png" /></figure>

## Discussion

* The presence of **recovery significantly influences CT estimation**, even though torque kinetics do not differ between groups.

* In untrained participants, **CT<sub>end-test</sub>** should be preferred and **CT<sub>exp</sub>** should be avoided.

* Extrapolation method should be further investigated.

* It seems necessary to adjust the all-out test so that it is less dependent on the participant's maximum voluntary contraction abilities.

## References

[1] M. Burnley, *Journal of applied physiology*, (2009)

[2] P.A. Merton, *The Journal of Physiology*, (1954)

[3] M. Burnley, A. Vanhatalo, A.M Jones, *Journal of applied physiology*, (2012)

[4] Morel B, Lapole T, Liotard C, et Hautier C, *Frontiers in Physiology* (2019)

<figure><img src="image_3.png" /><figcaption>Figure 2</figcaption></figure>

## Results

Both group had similar iMVCs (p=0,39) and VA% (p=0,41) kinetics during allout, but group **A** had **lower PTa on averages during the test** (p=0,02). A group × method interaction (p<0,001) indicated that **CT<sub>extrap</sub> was underestimated for group A** (-4,6% iMVC) **and overestimated for group B** (+4,8%) compared to **CT<sub>end-test</sub>** (fig.3). Furthermore, **CT<sub>exp</sub> was underestimated compared to the other methods** (p<0,002) for both groups (fig.3).

<figure><img src="image_4.png" /><figcaption>Figure 3</figcaption></figure>

## Acknowledgements

The authors would like to thank Léo Le Corre for the graphic illustration. A National Research Grant from the University of La Réunion (from the European Regional Development (FEDER) supported this work.
# Investigating critical torque estimation in untrained participants

Antonin Le Corre a, Nicolas A. Turpin a, Jérémie Begue a, Antoine Mariani a, Nathan Caron a, Georges Dalleau a
a Laboratoire IRISSE - EA 4075, UFR des Sciences de l'Homme et de l'Environnement, Université de La Réunion, 117 rue du Général Ailleret, 97430 Le Tampon, Île de La Réunion

## Introduction

During an all-out test, **peak torques decrease exponentially and reach a plateau called Critical Torque (CT)**, due to an accumulation of fatigue [1]. Both central and peripheral fatigue can be quantified by changes in Voluntary Activation level (VA%) and the Potentiated Torque amplitudes (PTa) [2, 3]. It has been shown that **PTa decrease exponentially during an all-out** [4] but, the plateau is not always **clearly identifiable**. We observed that **PTa could re-increase at the all-out end in some participants** (group A, fig.1) suggesting pacing strategies or neuromuscular recovery. While pacing strategies are difficult to prevent and biases CT estimation in untrained adults, it seems fundamental to **adjust CT estimation for these untrained participants**.

<figure><img src="image_2.png" /><figcaption>Figure 1</figcaption></figure>

We aimed to test and compare different methods of estimating CT, to reduce estimation bias in untrained adults

## Methods

* **34 untrained adults** performed an all-out test with the plantar flexors.

* Participants with an **extremum point** (fig.1) in **PTa kinetic** were **allocated to group A** (n=14; 31,21±9,69 yrs.) and **the others to group B** (37,70±14,20 yrs.).

* PTa and VA% were evaluated every 30s.

* Four critical torque (CT) estimation methods were compared:

* the **average of the last 30s** (CT<sub>end-test</sub>)

* the **asymptote of an exponential fit** (CT<sub>exp</sub>) in iMVCs kinetic

* the **minimum of a quadratic fit** (CT<sub>quad</sub>) in iMVCs kinetic

* a **method of extrapolation** (CT<sub>extrap</sub>) between the variations in PTa and the variations in iMVC (fig.2).

<figure><img src="image_3.png" /></figure>

## Discussion

* The presence of **recovery significantly influences CT estimation**, even though torque kinetics do not differ between groups.

* In untrained participants, **CT<sub>end-test</sub>** should be preferred and **CT<sub>exp</sub>** should be avoided.

* Extrapolation method should be further investigated.

* It seems necessary to adjust the all-out test so that it is less dependent on the participant's maximum voluntary contraction abilities.

## References

[1] M. Burnley, *Journal of applied physiology*, (2009)

[2] P.A. Merton, *The Journal of Physiology*, (1954)

[3] M. Burnley, A. Vanhatalo, A.M Jones, *Journal of applied physiology*, (2012)

[4] Morel B, Lapole T, Liotard C, et Hautier C, *Frontiers in Physiology* (2019)

## Results

Both group had similar iMVCs (p=0,39) and VA% (p=0,41) kinetics during allout, but group **A** had **lower PTa on averages during the test** (p=0,02). A group × method interaction (p<0,001) indicated that **CT<sub>extrap</sub> was underestimated for group A** (-4,6% iMVC) **and overestimated for group B** (+4,8%) compared to **CT<sub>end-test</sub>** (fig.3). Furthermore, **CT<sub>exp</sub>** was **underestimated compared to the other methods** (p<0,002) for both groups (fig.3).

<figure><img src="image_4.png" /><figcaption>Figure 3</figcaption></figure>

## Acknowledgements

The authors would like to thank Léo Le Corre for the graphic illustration. A National Research Grant from the University of La Réunion (from the European Regional Development (FEDER) supported this work.

<figure><img src="image_5.png" /><figcaption>Figure 2</figcaption></figure>

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UNIVERSITÉ DE LA RÉUNION
IRISSE
INGÉNIERIE
DE LA SANTE, DU SPORT
ET DE L'ENVIRONNEMENT

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UR

UNIVERSITÉ
DE LA RÉUNION

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