effect of resistance training volume with inertial flywheel on muscle adaptations in untrained men

Conditions: Resistance Training; Eccentric Exercise Training

Summary: 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.

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.

Eligibility criteria:
inclusion criteria: 1. self-reported levels of speaking, writing and understanding portuguese; 2. availability to participate in the research (initial meeting, initial and final tests, data collection); 3. have not been performing traditional resistance exercises for at least 6 months (untrained subjects); 4. have no previous experience with inertial flywheel devices; 5. answer no to all questions on the physical activity risk questionnaire - par-q; 6. have no medical contraindication of any kind. exclusion criteria: 1. have a history of recent osteomyoarticular injury; 2. have uncontrolled chronic diseases; 3. surgical procedures scheduled during interventions; 4. do not have the flexibility to adapt their diet to the guidelines offered during collection; 5. use medications or supplements that may interfere with the result, acting as an intervening variable.

Keywords: randomized clinical trial flywheel resistance training hypertrophy maximum voluntary isometric contraction