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ORIGINAL RESEARCH article

Front. Physiol.
Sec. Exercise Physiology
Volume 15 - 2024 | doi: 10.3389/fphys.2024.1531926
This article is part of the Research Topic Acute and Chronic Physiological Adaptations to Resistance Exercises Across Various Populations: Mechanisms and Practical Applications View all articles

The Effects of Eccentric Phase Tempo in Squats on Hypertrophy, Strength, and Contractile Properties of the Quadriceps Femoris Muscle

Provisionally accepted
Filip Kojic Filip Kojic 1Danimir Mandic Danimir Mandic 1Sasa Duric Sasa Duric 2*
  • 1 Faculty of Education, University of Belgrade, Belgrade, Serbia
  • 2 American University of the Middle East, Kuwait City, Kuwait

The final, formatted version of the article will be published soon.

    The aim of the present study was to investigate the effects impact of eccentric phase squat tempo in squats on hypertrophy, strength, and contractile properties of the quadriceps femoris (QF) muscle. Eighteen participants (10 males and 8 females, age 24.00 ± 1.70 years) with no resistance training (RT) experience in the last 8 months were randomized into two groups, each following a 7-week squat resistance training (RT) protocol with either a fast eccentric (FE, 1 s eccentric/0 s isometric/1 s concentric/0 s isometric) or slow eccentric (SE, 4 s eccentric/0 s isometric/1 s concentric/0 s isometric) tempo. The training intensity (60-70% RM), the number of sets (3-4), and the rest intervals (120 s) were consistent in both groups. The study measured changes in quadriceps cross-sectional area (CSA), one-repetition maximum (1RM) strength, and muscle contractile properties such as contraction time (Tc) and radial displacement (Dm), using tensiomyography (TMG). An ANCOVA model with baseline values as covariates was used to examine between-group differences. Results showed significant strength gains in both groups, with the SE group achieving greater 1RM increases (effect size [ES] = 1.60 vs. 0.99, p < 0.05).CSA increased for all QF muscles; however, the SE group exhibited significantly higher hypertrophy in the vastus lateralis (ES = 1.74 vs 1.37, p < 0.05). TMG analysis revealed decreased Dm in the rectus femoris for both groups (p < 0.05), while Tc significantly (ES = 1.33, p < 0.01) increased in the SE group. indicating increased muscle stiffness. Moreover, Tc significantly (p < 0.01) increased in the SE group, suggesting adaptations favoring slow-twitch fiber hypertrophy. These findings suggest that slower eccentric tempo in RT may optimize vastus lateralis hypertrophy and enhance strength while promoting muscle fiber-type specificity, contributing to the understanding of eccentric training's role in muscle adaptation.

    Keywords: tensiomiography (TMG), Contraction time, Radial displacement, Vastus lateralis, cross-cectional area (CSA), One-repetition maximum (1RM)

    Received: 21 Nov 2024; Accepted: 24 Dec 2024.

    Copyright: © 2024 Kojic, Mandic and Duric. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Sasa Duric, American University of the Middle East, Kuwait City, Kuwait

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