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Int J Sports Med
DOI: 10.1055/a-2719-7934
Training & Testing

Equating Unilateral and Bilateral Half-Squat Loads: Neuromuscular and Kinetic Analysis

Authors

  • Gian Mario Migliaccio  ‡

    1   Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Rome Open University, Rome, Italy

  • Enzo Iuliano  ‡

    2   Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italy

  • Pietro Picerno  ‡

    3   Department of Engineering, University of Sassari, Sassari, Italy

  • Drazen Cular 

    4   Faculty of Kinesiology, University of Split, Split, Croatia (Ringgold ID: RIN74422)
    5   Einstein, Startup for Research, Development, Education, Trade and Services, Split, Croatia
    6   European Institute for Talents, Education, Research & Development, Split, Croatia

  • Goran Kuvacic 

    4   Faculty of Kinesiology, University of Split, Split, Croatia (Ringgold ID: RIN74422)

  • Ghazi Racil 

    7   Department of Biological Sciences, Higher Institute of Sport and Physical Education of Gafsa, Gafsa, Tunisia
    8   Research Unit (LR 23JS01) “Sport Performance, Health & Society” Higher Institute of Sport and Physical Education of Ksar Said, Tunis, Tunisia

  • Carmen Ene-Voiculescu 

    9   Faculty of Physical Education and Sport, Ovidius University of Constanta, Constanta, Romania

  • Luca Russo  ‡

    2   Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italy

  • Wissem Dhahbi  ‡

      Research Unit: Sport Sciences, Health and Movement, High Institute of Sport and Physical Education of Kef, University of Jendouba, Kef, Tunisia
    11   Training Department, Police College, Qatar Police Academy, Doha, Qatar

  • Johnny Padulo  ‡

    12   Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy (Ringgold ID: RIN9304)

This research was supported by the Croatian Science Foundation under Project Grant No. [IP-2024-05-8340] and by the Faculty of Kinesiology, University of Split, Institutional Project Grant “Health, Longevity & Sport (HeLoS).” All grants contributed to different aspects of the study in compliance with the funding regulations.

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Abstract

This study aimed to develop predictive equations for unilateral (1-leg) half-squat exercise loads that would elicit equivalent neuromuscular activation, velocity, and force outputs as bilateral (2-leg) half-squat exercise loads. Twelve male soccer players (age 22.9±1.8 y, stature 1.8±0.1 m, and body mass 76.5±6.2 kg) performed both 1-leg and 2-leg half-squats using a Smith-machine. Surface electromyography of vastus lateralis and vastus medialis, barbell velocity and force outputs were measured across incremental loads. Linear regression analyses were conducted to develop predictive equations for 1-leg loads that would match 2-leg exercise outcomes. Three predictive equations were developed: (1) Equivalent muscle activation: 1-leg external load=50% of 2-leg external load –2 kg (r=0.923–0.997, p<0.05). (2) Equivalent barbell velocity: 1-leg external-load=71% of 2-leg external load –17.6 kg (r= –0.916 to 0.994, p<0.05). (3) Equivalent force-output: 1-leg external load=41% of 2-leg external load – 28 kg (r=0.937–0.998, p<0.05). This preliminary investigation provides initial predictive equations for equating unilateral and bilateral half-squat exercises, though validation on independent populations remains necessary. These tools enable practitioners to estimate equivalent loads between exercise modalities using a single one-repetition maximum assessment, facilitating targeted training and rehabilitation program development through accurate load prescription and performance comparisons. Further research is needed to validate these equations on large population and in different sports.

Keywords

Electromyography - load-velocity relationship - neuromuscular fatigue - strength assessment - neuromuscular profiling - functional longevity


Publication History

Received: 10 July 2025

Accepted after revision: 07 October 2025

Article published online:
24 November 2025

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