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Effects of deload periods in resistance training on muscle hypertrophy and strength endurance in untrained young men using a randomized within subject design
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  • Published: 24 February 2026

Effects of deload periods in resistance training on muscle hypertrophy and strength endurance in untrained young men using a randomized within subject design

  • Zarife Pancar1,
  • Muhammet Taha Ilhan2,
  • Muhammed Kaan Darendeli3,
  • Burak Karaca3,
  • Mehmet Ali Ikidag4,
  • Ali Muhittin Tasdogan5,
  • Mustafa Sencer Ulema3,
  • Nouf H. Alkhamees6,
  • Sameer Badri Al-Mhanna7,8,9 &
  • …
  • Alexios Batrakoulis10,11 

Scientific Reports , Article number:  (2026) Cite this article

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

This study aimed to investigate the effects of deload periods implemented through reductions in weekly set volume and training frequency at the midpoint and endpoint of an 8-week resistance training (RT) program on muscle hypertrophy and strength-endurance in untrained individuals. 19 untrained young men participated in the study using a within-subject design. Each participant’s legs and arms were randomly assigned to the continuous and deload training conditions. In the continuous condition, unilateral leg extension and biceps curl exercises were performed twice per week for 8 weeks (6–8 sets per exercise, 8–12RM). In the deload condition, a similar training program was followed; however, during weeks 4 and 8, the exercises were performed only once per week with 2 sets per exercise. Muscle thickness was measured with ultrasound, while strength-endurance was assessed with 10-repetition maximum (10RM) testing, pre- and post-intervention. Both conditions produced similar, statistically significant increases in quadriceps/biceps muscle thickness and 10RM (single exception: lateral 30%—deload, p = 0.073). No time × condition interactions were detected for muscle thickness or strength-endurance (p = 0.239–0.955); between-condition effects were small (ηp2 = 0.001–0.076), and all Δ 95% confidence intervals included zero. In conclusion, reducing training volume and frequency at the midpoint and endpoint of an 8-week resistance training program does not appear to hinder adaptations in muscle hypertrophy and strength-endurance in untrained young men.

Data availability

The raw data and materials associated with this study will be publicly available upon acceptance of the Stage 2 manuscript. The statistical analyses and results are already presented in tables and figures within the manuscript. Additionally, the raw data will be deposited in an open-access repository (Open Science Framework—OSF) to ensure transparency and reproducibility. The registration details are available at the following link (Date of registration: 12/01/2025): https://osf.io/6cgpt/?view_only=7a55420f9c0843838b7da349ba26195f. For additional inquiries regarding the data, please contact the corresponding author: (z_pancar@hotmail.com).

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Acknowledgements

The funders have/had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. This study acknowledges the fund support from Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2026R424), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.

Author information

Authors and Affiliations

  1. Department of Physical Education and Sport, Faculty Sport Science, Gaziantep University, 27310, Gaziantep, Turkey

    Zarife Pancar

  2. Department of Coaching Education, Faculty of Sport Sciences, Aydın Adnan Menderes University, 09010, Aydın, Turkey

    Muhammet Taha Ilhan

  3. Department of Physical Education and Sports, Institute of Health Sciences, Gaziantep University, Gaziantep, Turkey

    Muhammed Kaan Darendeli, Burak Karaca & Mustafa Sencer Ulema

  4. Department of Radiology, Faculty of Medicine, SANKO University, 27090, Gaziantep, Turkey

    Mehmet Ali Ikidag

  5. Department of Anesthesiology and Reanimation, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey

    Ali Muhittin Tasdogan

  6. Department of Rehabilitation Sciences, College of Health and Rehabilitation Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia

    Nouf H. Alkhamees

  7. Center for Global Health Research, Saveetha Medical College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Chennai, India

    Sameer Badri Al-Mhanna

  8. Department of Physiology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia

    Sameer Badri Al-Mhanna

  9. Department of Higher Studies, Al-Qasim Green University, Babylon, Iraq

    Sameer Badri Al-Mhanna

  10. Department of Life Sciences, European University Cyprus, Nicosia, Cyprus

    Alexios Batrakoulis

  11. Department of Physical Education and Sport Science, Democritus University of Thrace, Komotini, Greece

    Alexios Batrakoulis

Authors
  1. Zarife Pancar
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  2. Muhammet Taha Ilhan
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  3. Muhammed Kaan Darendeli
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Contributions

ZP, MTİ, EK, contributed to the study concept and study design. BK, MAİ, performed the statistical analysis and data interpretation. AMT, MSU, BK were responsible for the quality control of the data. MKD, MSU, ZP, AB and NHA performed the literature research and data extraction. NHA, SBA, AB, and ZP were responsible for the revision and academic proofreading of the manuscript. NHS, SBA, ZP and AB were responsible for project administration. All authors contributed to the writing of the manuscript and approved the final manuscript.

Corresponding authors

Correspondence to Zarife Pancar or Alexios Batrakoulis.

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Pancar, Z., Ilhan, M.T., Darendeli, M.K. et al. Effects of deload periods in resistance training on muscle hypertrophy and strength endurance in untrained young men using a randomized within subject design. Sci Rep (2026). https://doi.org/10.1038/s41598-026-40612-5

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  • Received: 30 January 2025

  • Accepted: 13 February 2026

  • Published: 24 February 2026

  • DOI: https://doi.org/10.1038/s41598-026-40612-5

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Keywords

  • Resistance training
  • Muscle hypertrophy
  • Strength-endurance
  • Deload
  • Training volume
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