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Completed

NCT Number: NCT07412600

High- and Low-Load Resistance Training

The goal of this clinical trial is to learn whether low-load resistance training performed to muscle failure can produce similar increases in muscle size and strength as high-load resistance training in healthy untrained young adult males.

The main questions it aims to answer are:

Does low-load resistance training (30% of one-repetition maximum) performed to failure increase muscle strength and muscle size to a similar extent as high-load resistance training (75% of one-repetition maximum)?

Are there differences in total training volume between low-load and high-load resistance training programs performed to failure?

Researchers will compare a low-load resistance training group to a high-load resistance training group to determine whether the magnitude of changes in muscle strength and hypertrophy differs between the two approaches.

Participants will:

Be randomly assigned to either a low-load (30% 1RM) or high-load (75% 1RM) resistance training group

Perform supervised leg extension exercises to the point of voluntary muscle fatigue three times per week for 6 weeks

Complete muscle strength testing (one-repetition maximum) before and after the training period

Undergo ultrasound measurements to assess muscle thickness and cross-sectional area of thigh muscles before and after the intervention

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Key information

Conditions

Resistance Training Muscle Hypertrophy

Age range

18 year–28 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Selcuk University

Meram, Konya, 04204, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male sex
  • Age between 18 and 28 years
  • Healthy status as determined by self-report health screening
  • No participation in structured resistance training or lower-limb power training within the previous 12 months
  • Engaging only in recreational physical activity (no systematic lower-body resistance training)
  • Willingness to maintain usual daily routines throughout the study period
  • Agreement to refrain from any structured lower-body resistance training during the 6-week intervention
  • Provision of written informed consent

Exclusion criteria

  • Any current or recent musculoskeletal injury affecting lower-limb function
  • History or presence of cardiovascular disease
  • History or presence of metabolic disorders
  • Resting hypertension (≥140/90 mmHg)
  • Regular tobacco use
  • Use of medications known to affect neuromuscular performance
  • Inability or unwillingness to comply with the training protocol

Treatment and study plan

Low-load resistance training (30% 1RM)

Other

Participants perform unilateral or bilateral leg extension exercise at 30% of their individually determined one-repetition maximum (1RM). Each training session consists of sets performed to volitional muscular failure. Training is conducted three times per week for 6 weeks under direct supervision. Load is adjusted if necessary to maintain the target relative intensity. All repetitions are performed using a controlled movement tempo.

High-load resistance training (75% 1RM)

Other

Participants perform the same leg extension exercise at 75% of their individually determined one-repetition maximum (1RM). As in the LLRT group, sets are performed to volitional muscular failure. Training frequency (three sessions per week), duration (6 weeks), supervision, exercise selection, and movement tempo are identical to the LLRT group.

Primary outcomes

  1. Maximal Dynamic Strength - Estimated One-Repetition Maximum (1RM) Using Submaximal Prediction and Epley Equation

    Time frame: Baseline (Week 0) and immediately after completion of the 6-week intervention (Week 6)

    Maximal strength will be estimated using a submaximal 1RM prediction protocol (8-10 repetitions) following a standardized warm-up. The highest load completed within the target repetition range will be used to calculate 1RM using the Epley equation (1RM = Load × [1 + 0.033 × repetitions]). Results will be expressed in kilograms (kg), with higher values indicating greater strength. Assessed at baseline and Week 4.

  2. Muscle Thickness (MT) and Cross-Sectional Area (CSA) - Assessed by B-Mode Ultrasonography (LOGIQ S8, GE Healthcare)

    Time frame: Baseline (Week 0) and immediately after completion of the 6-week intervention (Week 6)

    Muscle thickness (cm) and cross-sectional area (cm²) of the rectus femoris and vastus intermedius will be assessed using B-mode ultrasonography (LOGIQ S8, GE Healthcare, 2-8 MHz linear probe). Three images per site will be averaged for analysis. Higher values indicate greater muscle hypertrophy. Measurements performed at baseline and post-intervention by a blinded assessor.

Secondary outcomes

  1. Muscular Endurance - Repetitions to Volitional Failure at 50% of Estimated 1RM

    Time frame: Baseline (Week 0) and immediately after completion of the 6-week intervention (Week 6)

    Muscular endurance will be assessed by performing repetitions to volitional failure at 50% of baseline 1RM. The total number of completed repetitions will be recorded. Results expressed as repetition count, with higher values indicating greater endurance. Assessed at baseline and post-intervention.

Sponsors and collaborators

Lead sponsor

Akdeniz University

Other

Collaborators

  • Selcuk University

Registry information

Official study title

High- and Low-Load Resistance Training to Failure Result in Similar Muscular Adaptations in Untrained Young Males

Important dates

Study start
2021
Primary completion
2022
Study completion
2022
First posted
Feb 17, 2026
Registry last updated
Feb 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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