Effects of Inter-Set Rest Intervals on Muscle Damage After Flywheel Exercise in Untrained Men (RCT)

Summary

This randomized parallel-group clinical trial will compare the acute effects of three different inter-set rest intervals during a single lower-limb flywheel resistance exercise session in untrained men. Participants will be randomly allocated to one of three groups: 1-minute, 2-minute, or 3-minute inter-set rest interval. The primary outcome will be the change in maximal voluntary isometric contraction of the knee extensors 48 hours after exercise. Secondary outcomes will include mechanical variables during the exercise session, countermovement jump performance, knee flexor maximal voluntary isometric contraction, muscle soreness, pressure pain threshold, range of motion, ultrasound-derived muscle thickness and echo intensity, perceived exertion, perceived discomfort, perceived recovery status, creatine kinase, and lactate dehydrogenase.

Conditions

• Exercise-induced Muscle Damage

Interventions

BEHAVIORAL

Flywheel resistance exercise with 1-minute inter-set rest

Participants will perform a single lower-limb flywheel resistance exercise session using a 1-minute inter-set rest interval. The session will include squat, Romanian deadlift, knee extension, and knee flexion exercises. Each exercise will be performed for 4 sets of 2 preparatory repetitions followed by 8 valid repetitions, using the same flywheel inertia, exercise order, and execution instructions across all groups. Participants will be instructed to perform the concentric phase as fast as possible and to brake the eccentric phase during the final portion of the movement. The interval between exercises will be standardized at 3 minutes.

BEHAVIORAL

Flywheel resistance exercise with 2-minute inter-set rest

Participants will perform a single lower-limb flywheel resistance exercise session using a 2-minute inter-set rest interval. The session will include squat, Romanian deadlift, knee extension, and knee flexion exercises. Each exercise will be performed for 4 sets of 2 preparatory repetitions followed by 8 valid repetitions, using the same flywheel inertia, exercise order, and execution instructions across all groups. Participants will be instructed to perform the concentric phase as fast as possible and to brake the eccentric phase during the final portion of the movement. The interval between exercises will be standardized at 3 minutes.

BEHAVIORAL

Flywheel resistance exercise with 3-minute inter-set rest

Participants will perform a single lower-limb flywheel resistance exercise session using a 3-minute inter-set rest interval. The session will include squat, Romanian deadlift, knee extension, and knee flexion exercises. Each exercise will be performed for 4 sets of 2 preparatory repetitions followed by 8 valid repetitions, using the same flywheel inertia, exercise order, and execution instructions across all groups. Participants will be instructed to perform the concentric phase as fast as possible and to brake the eccentric phase during the final portion of the movement. The interval between exercises will be standardized at 3 minutes.

Sponsors & Collaborators

• Federal University of Vicosa

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

40 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-06-30

Primary Completion

2026-07-31

Completion

2026-07-31

Countries

• Brazil

Study Locations