Training with peak resistance at stretched or shortened muscle lengths produces similar muscle growth when range of motion is identical.
Original: We Need to Talk About Jeremy Ethier’s New Study
Evidence shows muscle growth is not significantly different when peak resistance occurs at longer versus shorter muscle lengths within the same range of motion.
Quick Answer
The new study found no significant difference in muscle growth between training with a resistance challenge biased toward longer muscle lengths versus shorter muscle lengths. Both conditions used identical exercises, range of motion, volume, and intensity, but varied only in where peak torque occurred during the movement. This suggests that for muscle hypertrophy, the location of peak difficulty within a full range of motion does not significantly impact results.
Claims (10)
1. New lifters might grow more from stretching muscles than experienced lifters, but we don’t know for sure because most studies use beginners.
2. If you only do part of a movement but stretch the muscle more during that part, you might grow more than doing the full movement if the full movement doesn’t stretch the muscle much.
3. Where you feel the most resistance during a workout doesn't change how much your muscles grow, as long as you move through the same range.
4. Holding a muscle stretched while pushing against something still makes it grow more than holding it short, even if you don’t move.
5. When a muscle crosses two joints, stretching it at one joint makes it longer overall, which can make it grow more when you exercise it.
6. Stretching your muscles during exercise helps, but working out hard, doing enough reps, and showing up regularly matter way more.
7. When you stretch your triceps by raising your arms overhead and then extend your elbows, your triceps grow more than when you don’t stretch them.
8. Some muscles might respond differently to how you stretch them during exercise, depending on how they’re built.
9. Moving your muscles through their full stretch and contraction makes them grow more than only doing part of the movement, especially at the stretched end.
10. When you curl with your arms behind you, your biceps stretch more and grow more than when you curl with your arms in front.
Key Takeaways
- •Problem: People thought training muscles when they’re stretched out (longer length) might grow more than when they’re squeezed (shorter length), but this wasn’t proven.
- •Core methods: Chest flies, reverse flies, hip extensions, lateral raises, each performed with two different resistance patterns: one where it’s hardest at the start (muscle stretched) and one where it’s hardest at the end (muscle shortened).
- •How methods work: Machines were set so one side felt hardest at the beginning of the movement (muscle at longest length), and the other side felt hardest at the end (muscle at shortest length), but both sides moved through the exact same range.
- •Expected outcomes: Both sides grew the same amount—no difference in muscle size between training with peak difficulty at long vs. short muscle lengths.
- •Implementation timeframe: Results were seen after 10 weeks of training twice per week.
Overview
The problem addressed is whether training muscles at longer versus shorter lengths—defined by where peak resistance occurs within a full range of motion—affects muscle hypertrophy. The solution preview is that a within-subject study using Prime Fitness machines to create opposing resistance profiles (lengthened-bias vs. shortened-bias) found no significant difference in muscle growth, suggesting that peak torque location alone does not drive hypertrophy when total range of motion, volume, and intensity are matched.
Key Terms
How to Apply
- 1.Use a machine like Prime Fitness that allows independent resistance profiles for each side of the body, or replicate the setup with adjustable resistance curves on cable machines.
- 2.Perform chest flies, reverse flies, hip extensions, and lateral raises with two different resistance settings: one side set to provide peak resistance at the start of the movement (long muscle length), the other side set to provide peak resistance at the end of the movement (short muscle length).
- 3.Ensure both sides use identical total range of motion, tempo (controlled), and rest periods (2 minutes between sets).
- 4.Train each exercise with 4–5 sets per session, 8–12 repetitions per set, to momentary muscular failure, adjusting weight each set to stay in the target rep range.
- 5.Continue this protocol twice per week for 10 weeks, measuring muscle size changes (e.g., via DEXA or ultrasound) on both sides to compare growth.
After 10 weeks of training, muscle growth (cross-sectional area or volume) will be statistically similar between the side trained with peak resistance at longer muscle lengths and the side trained with peak resistance at shorter muscle lengths.
Additional Links
Claims (10)
1. New lifters might grow more from stretching muscles than experienced lifters, but we don’t know for sure because most studies use beginners.
2. If you only do part of a movement but stretch the muscle more during that part, you might grow more than doing the full movement if the full movement doesn’t stretch the muscle much.
3. Where you feel the most resistance during a workout doesn't change how much your muscles grow, as long as you move through the same range.
4. Holding a muscle stretched while pushing against something still makes it grow more than holding it short, even if you don’t move.
5. When a muscle crosses two joints, stretching it at one joint makes it longer overall, which can make it grow more when you exercise it.
6. Stretching your muscles during exercise helps, but working out hard, doing enough reps, and showing up regularly matter way more.
7. When you stretch your triceps by raising your arms overhead and then extend your elbows, your triceps grow more than when you don’t stretch them.
8. Some muscles might respond differently to how you stretch them during exercise, depending on how they’re built.
9. Moving your muscles through their full stretch and contraction makes them grow more than only doing part of the movement, especially at the stretched end.
10. When you curl with your arms behind you, your biceps stretch more and grow more than when you curl with your arms in front.
Related Content
Claims (10)
When resistance is applied such that peak torque occurs at either the longest or shortest muscle length during a movement with identical total range of motion, muscle hypertrophy is not significantly different between conditions.
Training muscles through a full range of motion or lengthened partials produces greater hypertrophy than training through shortened partials, particularly in distal muscle regions.
Total training volume, training intensity, and consistency are more significant determinants of muscle hypertrophy than the specific muscle length at which training occurs.
Exercises that position biarticulate muscles at longer lengths (via joint angle manipulation) produce greater hypertrophy in those biarticulate muscle heads compared to exercises that place them at shorter lengths.
Curling exercises that position the shoulder in extension (lengthening the biceps) produce greater hypertrophy in the biceps brachii compared to exercises that position the shoulder in flexion (shortening the biceps).