Directional Asymmetry of Crossover Neuromuscular Fatigue Following Unilateral Handgrip Exercise in Adults and Prepubertal Children.

Overview

1. Tunisian Research Laboratory “Sport Performance Optimisation”, National Center of Medicine and Science in Sports, Tunis 1003, Tunisia
2. Research Unit (UR22JS01) “Sport Sciences, Health and Movement”, High Institute of Sport and Physical Education of Kef, University of Jendouba, Le Kef 7100, Tunisia; (W.D.); (M.B.)
3. Training Department, Police College, Qatar Police Academy, Doha 7157, Qatar
4. Physical Education and Sports Teaching Department, Faculty of Sports Sciences, Atatürk University, Erzurum 25240, Türkiye
5. Department of Physical Education and Sport, Faculty of Sciences, Physical Education and Informatics, National University of Science and Technology Politehnica Bucharest, Pitesti University Center, 060042 Pitesti, Romania
6. Research Laboratory LR19SP01, Physical and Rehabilitation Department, Sahloul Hospital of Sousse, Sousse 4054, Tunisia
7. Research Laboratory LR19SP01, Faculty of Medicine of Sousse, University of Sousse, Sousse 4002, Tunisia
8. Research Laboratory LR12SP09 ‘Heart Failure’, Faculty of Medicine ‘Ibn el Jazzar’ of Sousse, Farhat HACHED University Hospital, University of Sousse, Sousse 4002, Tunisia
9. Department of Physiology and Functional Explorations, Farhat HACHED University Hospital, Sousse 4002, Tunisia
10. CRCI (Centre de Recherche et Collaboration Innovative), UPSAT-Sousse, University Central Group, Tunis 1002, Tunisia

Abstract

Background and Objectives: This study investigated whether crossover neuromuscular fatigue following unilateral handgrip exercise exhibits directional asymmetry, testing whether dominant-limb fatigue produces greater contralateral performance decrements than non-dominant-limb fatigue in adults and pre-peak-height-velocity children. Materials and Methods: Thirty-three healthy, right-handed males (16 adults: 22.5 ± 1.6 years; 17 pre-peak-height-velocity boys: 11.2 ± 0.8 years, maturity offset −2.2 ± 0.4 years) completed three counterbalanced experimental sessions (48–72 h apart): dominant-arm fatigue, non-dominant-arm fatigue, and control. The fatigue protocol consisted of 20 consecutive 6 s maximal voluntary isometric handgrip contractions. Primary outcomes were percentage changes in maximal voluntary isometric contraction of the contralateral limb across handgrip, elbow flexor, and elbow extensor muscle groups. Results: The experimental condition explained approximately 64% of crossover variance in adults (ηp2 = 0.650, ηG2 = 0.421) and children (ηp2 = 0.638, ηG2 = 0.448; both p < 0.001). Dominant-limb fatigue elicited substantially greater contralateral decrements than non-dominant-limb fatigue in adults (−11.00% vs. −3.92%, dz = −1.07) and children (−12.71% vs. −3.08%, dz = −1.33), representing 2.5- to 3.5-fold greater transfer efficiency (both p < 0.001). Age-group comparisons revealed no differences in crossover susceptibility (p = 0.627, ηp2 = 0.008), with equivalence testing confirming developmental invariance. Crossover effects extended to heterologous proximal muscles without magnitude differences (p > 0.13). Conclusions: Crossover fatigue (contralateral performance decrement following unilateral exercise) exhibited directional asymmetry, with dominant-limb protocols eliciting 2.5- to 3.5-fold greater contralateral decrements. This pattern aligns with asymmetric transcallosal inhibitory projections demonstrated in prior transcranial magnetic stimulation studies, though direct neurophysiological confirmation was not obtained. Functional equivalence between pre-peak-height-velocity children and adults indicates that interhemispheric transfer mechanisms achieve operational maturity before peak height velocity. Extension to heterologous muscles implicates supraspinal mechanisms. The findings establish normative parameters for clinical populations with compromised transcallosal integrity.

Reproduced under the paper's license (CC BY), from the paper cited above.

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Data

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• figshare:31290073, at figshare; found in “Data Availability Statement”

Data Availability Statement

De-identified raw data are available in the Figshare repository (https://doi.org/10.6084/m9.figshare.31290073). Complete analysis code (Python 3.11.6), session information, package versions, and de-identified raw data are additionally archived in the Open Science Framework repository (https://osf.io/5y872 (accessed on 25 February 2026); DOI: https://doi.org/10.17605/OSF.IO/WDSQG). No data or code pertinent to reproducing the reported analyses are withheld.

Reproduced under the paper's license (CC BY), from the paper cited above.

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Version 1, 30 September 2026: the first record

Recorded: type, language, journal, volume, issue, pages, dates, 7 authors, 11 keywords, 11 MeSH terms, 55 references.

Cite

This paper

Othman, A. B., Dhahbi, W., Bessifi, M., Ceylan, H. İ., Stefanica, V., Moncer, R., & Ben Saad, H. (2026). Directional Asymmetry of Crossover Neuromuscular Fatigue Following Unilateral Handgrip Exercise in Adults and Prepubertal Children. Medicina (Kaunas, Lithuania), 62(3), 471. https://doi.org/10.3390/medicina62030471

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