Journal of Applied Physiology · Oct 22, 2026

Effects of ageing on fatigue resistance and neuromuscular control of the trunk extensor muscles during isokinetic contractions

By Parrella M, Arvanitidis M, Borzuola R et al.

Trunk extensor endurance is important for preserving spinal function and physical independence with ageing. However, little is known about trunk extensor endurance during dynamic tasks and the associated neuromuscular responses in older adults. This study compared trunk extensor endurance and the spatial distribution of lumbar erector spinae (LES) activity in 20 young and 20 healthy older adults during an isokinetic concentric trunk extension task performed at 35% of maximal voluntary contraction until voluntary exhaustion. High-density surface electromyography signals were recorded bilaterally from the LES. Endurance was quantified as the total number of repetitions completed. Normalised root mean square (RMSnorm), mean power frequency (MNF), centroid coordinates of the RMS map (mediolateral, x; craniocaudal, y), entropy, and coefficient of variation (CoV) of torque were calculated over five epochs (0, 25, 50, 75, and 100% of endurance time). Compared with young adults, older adults completed more repetitions (p = 0.012) and exhibited higher torque CoV throughout most of the task (p < 0.001). Regardless of fatigue progression, older adults exhibited higher RMSnorm values bilaterally, with a left-right asymmetry in LES activation (p = 0.021). They also showed a more caudal and medial centroid location (p = 0.022 and p < 0.001, respectively), and higher entropy in the right LES than young adults (p = 0.004). Healthy older adults demonstrated greater trunk extensor endurance despite reduced torque steadiness, accompanied by alterations in the magnitude and spatial organisation of LES activity, indicating that greater endurance was not associated with superior neuromuscular control in ageing.

doi.org/10.1152/japplphysiol.90066.2026PubMed 42932896Mechanisms