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Completed

NCT Number: NCT06924060

EFFECT OF RESISTANCE TRAINING VOLUME WITH INERTIAL FLYWHEEL ON MUSCLE ADAPTATIONS IN UNTRAINED MEN

Muscular strength is essential for health and quality of life, impacting body composition, balance, locomotion, functional independence, and mental health. Resistance training (RT) is the primary way to increase strength and muscle hypertrophy. Traditionally, RT programs rely on gravity, which can limit muscle activation, especially during the eccentric phase of movement. To improve outcomes, it is important to include methods that intensify muscle work during this phase.

Flywheel resistance Training (FWRT) was developed to increase overload during the eccentric phase by harnessing the energy generated during the concentric phase and applying it to the eccentric phase. This type of training has shown positive results in several studies, improving strength, hypertrophy, jump performance, aerobic endurance, agility, and running economy.

However, there are still no studies that define how the variables of FWRT should be effectively prescribed. Properly adjusting these variables can optimize muscle adaptations and improve physical fitness and health indices. Therefore, in this study, the number of sets will be evaluated to investigate whether a higher number of sets can lead to greater muscle adaptations.

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Key information

Conditions

Resistance Training Eccentric Exercise Training Hypertrophy Pathological Conditions, Anatomical Pathological Conditions, Signs and Symptoms

Age range

18 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Federal University at Viçosa

Viçosa, Minas Gerais, 36570-900, Brazil

About this study

Thirty young men will be randomly assigned to three groups: 2 sets, 3 sets, and 4 sets of Flywheel Resistance Training (FWRT). The interventions will take place at the Department of Physical Education at the Federal University of Vicosa, with all sessions supervised by certified physical education professionals. Follow-up will be conducted through WhatsApp messages and phone calls. All groups will train twice a week for eight weeks. Participants from all experimental groups will perform FWRT on a multi-leg isoinertial machine targeting both upper and lower body muscles. Each session will include 4 exercises, performed for 8 repetitions, with a 2-minute rest between sets and exercises. Training progression will be adjusted based on the participant's ability to exceed the suggested maximum repetitions with the same mobilized weight. The exercises will target various muscle groups, including leg extensions, leg curls, bicep curls, and triceps french press.

Participants will be evaluated at two points during the training program: pre-intervention and post-intervention. Muscle strength of the upper and lower limbs will be assessed through one-repetition maximum (1RM) tests on a knee extension or elbow flexion machine and through maximum voluntary isometric contraction (MVIC), evaluated with a load cell. The muscle thickness of the knee extensors and elbow flexors will be measured using a B-mode ultrasound. Load control will be monitored through the following scales: Total Quality of Recovery (TQR) and Visual Analog Scale for Delayed Onset Muscle Soreness (VAS-DOM), and after each set, by the Subjective Perception of Effort (OMNI-RES). To ensure adequate protein intake, at the end of each training session, participants will receive a dose of Whey Protein, based on data collected from their initial food recall and determined by a nutritionist. Anthropometric evaluation will include the measurement of: a) body mass using an electronic/digital scale with 100g resolution , and b) height using a millimetric stadiometer. The procedures used for body mass and height measurement will follow the protocols based on the measurement standards of the International Society for the Advancement of Anthropometry.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Self-reported levels of speaking, writing and understanding Portuguese;
  • Availability to participate in the research (initial meeting, initial and final tests, data collection);
  • Have not been performing traditional resistance exercises for at least 6 months (untrained subjects);
  • Have no previous experience with inertial flywheel devices;
  • Answer no to all questions on the Physical Activity Risk Questionnaire - PAR-Q;
  • Have no medical contraindication of any kind.

Exclusion criteria

  • Have a history of recent osteomyoarticular injury;
  • Have uncontrolled chronic diseases;
  • Surgical procedures scheduled during interventions;
  • Do not have the flexibility to adapt their diet to the guidelines offered during collection;
  • Use medications or supplements that may interfere with the result, acting as an intervening variable.

Treatment and study plan

Flywheel Resistance Training with two sets

Behavioral

For each training session, 4 generic exercises will be performed, involving small and large muscle groups (leg extension, leg flexion, biceps curl, triceps french press). They will perform 2 sets of 8 repetitions, with a 2-minute break between exercises and sets. They will perform these exercises at a high intensity (always 10 on the OMNI-RES Scale).

Other names: Flywheel Inertial Training, Eccentric Training

Flywheel Resistance Training with four sets

Behavioral

For each training session, 4 generic exercises will be performed, involving small and large muscle groups (leg extension, leg flexion, biceps curl, triceps french press). They will perform 4 sets of 8 repetitions, with a 2-minute break between exercises and sets. They will perform these exercises at a high intensity (always 10 on the OMNI-RES Scale).

Other names: Flywheel Inertial Training, Eccentric Training

Flywheel Resistance Training with six sets

Behavioral

For each training session, 4 generic exercises will be performed, involving small and large muscle groups (leg extension, leg flexion, biceps curl, triceps french press). They will perform 6 sets of 8 repetitions, with a 2-minute break between exercises and sets. They will perform these exercises at a high intensity (always 10 on the OMNI-RES Scale).

Other names: Flywheel Inertial Training, Eccentric Training

Primary outcomes

  1. Maximum isometric voluntary contraction (upper extremities)

    Time frame: Baseline and after eight weeks

    To evaluate the Maximum isometric voluntary contraction (MIVC) of the upper extremities, a load cell or extensometric cell with a sampling frequency of 1000 Hz will be used.

  2. Maximum isometric voluntary contraction (lower extremities)

    Time frame: Baseline and after eight weeks

    To evaluate the Maximum isometric voluntary contraction (MIVC) of the lower extremities, a load cell or extensometric cell with a sampling frequency of 1000 Hz will be used.

  3. 1 RM test (elbow flexors)

    Time frame: Baseline and after eight weeks

    To perform the one repetition maximum (1RM) test, the load cell will be placed on a Cross Over machine (Scorpions Fitness, Brazil), so that one of its ends is fixed by means of a chain to the lower part of a stirrup-type handle and the other end is fixed to the steel cable, which is subjected to traction when the machine's lever arm is moved. Before performing the test, the device will be adjusted so that the subject's elbow is at a 90° flexion angle.

  4. 1 RM test (knee extension)

    Time frame: Baseline and after eight weeks

    To perform the one repetition maximum test (1RM), the knee extension exercise or elbown flexion will be used on a BH fitness® Nevada Pro-t extension machine. To perform the test, the volunteer will be asked to extend the knee to form an angle of approximately 180° (final position) and return to the initial position.

  5. Muscle power (upper extremities)

    Time frame: Baseline and after eight weeks

    The evaluation of power elbow flexors will be assessed using the same machine used to assess 1RM. The load for assessing power should be used, obtained from the percentage value of 1RM (40%, 60% and 80% of 1RM), so that the subject performs the elbow flexion movement (concentric phase of the movement) at the highest possible speed. The return of the elbow to the initial position will be performed in a controlled manner, with a pause of one to two seconds, to prevent the effect of the accumulated elastic force from interfering with the next execution. A linear position transducer or Encoder will be used, with a sampling frequency of 1000 Hertz to determine the power values. Through this instrument it will be possible to obtain information on average muscle power (MMP) and peak muscle power (PP).

  6. Muscle power (lower extremities)

    Time frame: Baseline and after eight weeks

    The evaluation of lower limb muscle power will be performed using the same knee extension machine used in the exercise sessions, starting from the same initial position (90º of kneeling flexion) and reaching the same final position (180º of knee extension) as the test of 1RM. The load for assessing power should be used, obtained from the percentage value of 1RM (40%, 60% and 80% of 1RM), so that the subject performs the knee extension movement (concentric phase of the movement) at the highest possible speed. The return of the knee to the initial position will be performed in a controlled manner, with a pause of one to two seconds, to prevent the effect of the accumulated elastic force from interfering with the next execution. A linear position transducer or Encoder will be used, with a sampling frequency of 1000 Hertz.

  7. Muscle adaptations

    Time frame: Baseline and after eight weeks

    The muscle thickness of the knee extensors and elbow flexors will be measured using a B-mode ultrasound. Image acquisition will be performed by an experienced and previously trained researcher. The image will be considered suitable for analysis when the muscle-bone and subcutaneous adipose tissue-muscle interfaces are identified. The image will then be saved and analyzed in Image-J by the same experienced evaluator.

Secondary outcomes

  1. Delayed Onset Muscle Soreness

    Time frame: Before each training session during the 8 weeks of intervention

    To assess the history of Delayed Onset Muscle Soreness, the Visual Analog Scale for Delayed Onset Muscle Soreness (VAS-DOM) will be used to identify whether there are changes throughout the intervention for this variable, that is, whether the volunteer gets used to the intervention and feels less pain throughout the sessions.

  2. Subjective Perception of Effort

    Time frame: Before each training session during the 8 weeks of intervention

    To assess the subjective perception of effort, the Subjective Perception of Effort (OMINI-RES) scale will be used, in order to identify whether there are changes throughout the intervention for this variable, that is, whether the volunteer gets used to the intervention and feels a lower perception of effort throughout the sessions.

Sponsors and collaborators

Lead sponsor

Federal University of Vicosa

Other

Registry information

Official study title

EFFECT OS RESISTANCE TRAINING VOLUME WITH INERTIAL FLYWHEEL ON MUSCLE ADAPTATIONS IN UNTRAINED MEN: A RANDOMIZED CLINICAL TRIAL

Acronym: RCT

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Apr 11, 2025
Registry last updated
Aug 6, 2025

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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