Muscle Hypertrophy, Resistance Training
Conditions
Brief summary
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
Interventions
OTHERLow-load resistance training (30% 1RM)
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.
OTHERHigh-load resistance training (75% 1RM)
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.
Sponsors
Akdeniz University
Selcuk University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
SINGLE (Investigator)
Eligibility
Sex/Gender
MALE
Age
18 Years to 28 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Maximal Dynamic Strength - Estimated One-Repetition Maximum (1RM) Using Submaximal Prediction and Epley Equation | 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. |
| Muscle Thickness (MT) and Cross-Sectional Area (CSA) - Assessed by B-Mode Ultrasonography (LOGIQ S8, GE Healthcare) | 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
| Measure | Time frame | Description |
|---|---|---|
| Muscular Endurance - Repetitions to Volitional Failure at 50% of Estimated 1RM | 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. |
Countries
Turkey (Türkiye)
Outcome results
None listed