The association of reactive balance control and spinal curvature under lumbar muscle fatigue

Erika Zemková; Alena Cepková; José M Muyor

doi:10.7717/peerj.11969

The association of reactive balance control and spinal curvature under lumbar muscle fatigue

PeerJ. 2021 Aug 10:9:e11969. doi: 10.7717/peerj.11969. eCollection 2021.

Authors

Erika Zemková^{1

2}, Alena Cepková³, José M Muyor⁴

Affiliations

¹ Department of Biological and Medical Sciences, Faculty of Physical Education and Sport, Comenius University Bratislava, Bratislava, Slovakia.
² Sports Technology Institute, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Bratislava, Slovakia.
³ Centre of Languages and Sports, Faculty of Mechanical Engineering, Slovak University of Technology, Bratislava, Slovakia.
⁴ Laboratory of Kinesiology, Biomechanics and Ergonomics, Health Research Centre, University of Almería, Almería, Spain.

Abstract

Background: Although low back fatigue is an important intervening factor for physical functioning among sedentary people, little is known about its possible significance in relation to the spinal posture and compensatory postural responses to unpredictable stimuli. This study investigates the effect of lumbar muscle fatigue on spinal curvature and reactive balance control in response to externally induced perturbations.

Methods: A group of 38 young sedentary individuals underwent a perturbation-based balance test by applying a 2 kg load release. Sagittal spinal curvature and pelvic tilt was measured in both a normal and Matthiass standing posture both with and without a hand-held 2 kg load, and before and after the Sørensen fatigue test.

Results: Both the peak anterior and peak posterior center of pressure (CoP) displacements and the corresponding time to peak anterior and peak posterior CoP displacements significantly increased after the Sørensen fatigue test (all at p < 0.001). A lumbar muscle fatigue led to a decrease of the lumbar lordosis in the Matthiass posture while holding a 2 kg load in front of the body when compared to pre-fatigue conditions both without a load (p = 0.011, d = 0.35) and with a 2 kg load (p = 0.000, d = 0.51). Also the sacral inclination in the Matthiass posture with a 2 kg additional load significantly decreased under fatigue when compared to all postures in pre-fatigue conditions (p = 0.01, d = 0.48). Contrary to pre-fatigue conditions, variables of the perturbation-based balance test were closely associated with those of lumbar curvature while standing in the Matthiass posture with a 2 kg additional load after the Sørensen fatigue test (r values in range from -0.520 to -0.631, all at p < 0.05).

Conclusion: These findings indicate that lumbar muscle fatigue causes changes in the lumbar spinal curvature and this is functionally relevant in explaining the impaired ability to maintain balance after externally induced perturbations. This emphasizes the importance for assessing both spinal posture and reactive balance control under fatigue in order to reveal their interrelations in young sedentary adults and predict any significant deterioration in later years.

Keywords: Compensatory postural responses; Endurance of the hip and back extensor muscles; Matthiass test; Perturbation-based balance test; Spinal posture; Sørensen fatigue test.

Grants and funding

This work was supported by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and the Slovak Academy of Sciences (No. 1/0089/20) and the Slovak Research and Development Agency under the contract No. APVV-15-0704. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.