Muscle Hypertrophy: Effective Repetitions vs. Total Volume
Date of Award
Master of Science in Exercise Science
Progressive overload is a concept in resistance training design where training volume (volume = weight x repetitions x time x distance) is increased over time to illicit neuromuscular and hypertrophic adaptations. However, intensity (the percentage of effort relative to maximum effort) is an often overlooked limitation of training volume. To address the limitation, the theory of effective repetitions describes a degree of intensity needed to be attained before repetitions start creating any measureable amount of hypertrophy adaptation. In this study, the effective repetitions are estimated to begin at an RPE of 6.
This study aims to analyze the relationship between hypertrophy adaptations and the stimulus, a combination of total training volume and intensity via rate of perceived exertion (RPE) to the quadriceps using the leg extensions exercise for resistance-trained young men. The stimulus in one leg will change by increasing the number of repetitions performed in the prescribed number of sets to achieve a predetermined RPE that increases each week, whereas the same number of total repetitions (to keep the training volume constant) spread out over more sets to maintain a stagnant baseline RPE throughout the sets will be prescribed in the control leg. This study will compare the effects of these progressive overload protocols on lower body muscle hypertrophy over a 9-week study period.
Sixty four participants with at least two years of consistent and recent lower body resistance training experience will be randomly assigned to one of four protocol groups (PG) (16 participants per group): A low (5 sets) or high (8 sets) volume group, both with a low intensity (5-8 RPE) and high intensity (7-10 RPE) group. A progressing RPE Effective Repetitions vs. Total Volume 3 structure will be used in the PG legs, while the control group (CG) legs will be maintaining baseline RPE of 5 or 7 in the other leg over as many sets as are needed to equate for the volume of the first leg from session to session. Participants will perform their respective resistance training protocols using single-leg, machine leg extensions twice per week. Prior to the start of and immediately following the protocol, lab tests will be conducted utilizing 15 repetition maximum tests on the leg extension machine with EMG readings to measure muscle activity after ultrasound readings are taken to measure the muscle thickness of the quadriceps.
The protocol will provide insight on the effective repetitions concept as it pertains to young resistance trained men over a 9 week period. A 9 week study period is a fairly typical medium duration hypertrophy cycle that should provide enough time to indicate potential longer term hypertrophy effects and influences on fatigue accumulation. The effective repetitions theory as a determinant of muscle hypertrophy could change the landscape of programming to account for the minimum effective stimulus, maximum recoverable stimulus, and mediate overtraining to achieve optimal hypertrophic responses.