Lengthened partial repetitions elicit similar muscular adaptations as full range of motion repetitions during resistance training in trained individuals.
Level 2 - randomized trial
Within-participant randomized controlled trial
PubMed 39959841 · doi:10.7717/peerj.18904
What was done
Thirty healthy, resistance-trained participants completed an 8-week upper-body resistance training program (2 sessions per week, 4 exercises per session, 4 sets per exercise). In a within-participant design, each participant's upper extremities were randomly assigned to either lengthened partial repetitions (LPs) or full range of motion (ROM), with all other training variables matched between limbs. Muscle hypertrophy of the elbow flexors and extensors was measured via B-mode ultrasonography at 45% and 55% of humeral length. Muscle strength-endurance was assessed using a unilateral 10-repetition-maximum (10-RM) lat pulldown test under both partial and full ROM conditions. Data were analyzed using Bayesian posterior distributions and Bayes factors.
What was found
Both muscle thickness changes and unilateral lat pulldown 10-RM improvements were similar between lengthened partials and full ROM conditions. Results showed point estimates close to zero, with Bayes factors ranging from 0.16 to 0.30, providing moderate support for the null hypothesis of equal improvement across interventions. Exact numerical values for baseline and post-intervention muscle thickness measurements and 10-RM loads were not reported in the abstract.
Why it matters
This study indicates that lengthened partial repetitions provide comparable upper-body hypertrophic and strength-endurance adaptations to full range of motion training, reinforcing the importance of loading the muscle in its lengthened position.
Limits
The sample size was small (n = 30) and the intervention duration was relatively brief (8 weeks). The study examined only upper-body musculature in resistance-trained individuals, so findings may not generalize to lower-body training or untrained populations. Raw numerical adaptation values were not provided in the abstract.
Cited by
- supports Partial repetitions performed specifically in the lengthened position produce similar muscle hypertrophy to full range of motion exercises.