Torque Regulation Is Influenced by the Nature of the Isometric Contraction

Philipp Bauer; João Sá Gomes; João Oliveira; Paulo Santos; Pedro Pezarat-Correia; João R Vaz

doi:10.3390/s23020726

Torque Regulation Is Influenced by the Nature of the Isometric Contraction

Sensors (Basel). 2023 Jan 9;23(2):726. doi: 10.3390/s23020726.

Authors

Philipp Bauer^{1

2}, João Sá Gomes^{1

2}, João Oliveira¹, Paulo Santos¹, Pedro Pezarat-Correia¹, João R Vaz^{1

2}

Affiliations

¹ Centro Interdisciplinar de Performance Humana (CIPER), Neuromuscular Research Lab, Faculty of Human Kinetics, University of Lisbon, 1495-751 Lisbon, Portugal.
² Interdisciplinary Research Centre Egas Moniz (CiiEM), Egas Moniz School of Health & Science, 2829-511 Almada, Portugal.

Abstract

The present study aimed to investigate the effects of a continuous visual feedback and the isometric contraction nature on the complexity and variability of force. Thirteen healthy and young male adults performed three MVCs followed by three submaximal isometric force tasks at a target force of 40% of their MVC for 30 s, as follows: (i) push isometric task with visual feedback (P_visual); (ii) hold isometric task with visual feedback (H_visual); (iii) hold isometric task without visual feedback (H_non-visual). Force complexity was evaluated through sample entropy (SampEn) of the force output. Force variability was analyzed through the coefficient of variation (CV). Results showed that differences were task-related, with P_visual showing higher complexity (i.e., higher SampEn) and decreased variability (i.e., lower CV) when compared with the remaining tasks. Additionally, no significant differences were found between the two hold isometric force tasks (i.e., no influence of visual feedback). Our results are promising as we showed these two isometric tasks to induce different motor control strategies. Furthermore, we demonstrated that visual feedback's influence is also dependent on the type of isometric task. These findings should motivate researchers and physiologists to shift training paradigms and incorporate different force control evaluation tasks.

Keywords: entropy; force control; nonlinear analysis; variability.

MeSH terms

Entropy
Feedback, Sensory
Humans
Isometric Contraction* / physiology
Male
Muscle, Skeletal* / physiology
Torque

Grants and funding

J.R.V. and P.P.-C. were partly supported by the Fundação para a Ciência e Tecnologia under grant number UIDB//2020 to CIPER–Centro Interdisciplinar para o Estudo da Performance Humana (unit:447).