House of Hypertrophy
Training with peak resistance at stretched or shortened muscle lengths produces similar muscle growth when range of motion is identical.
Evidence shows muscle growth is not significantly different when peak resistance occurs at longer versus shorter muscle lengths within the same range of motion.
We checked the science
our breakdown of the video
10 claims, each mapped to its moment in the video
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.
Strong evidence from clinical studies backs this claim.
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.
Not enough evidence yet — take this with caution.
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.
Evidence points in both directions — no clear conclusion yet.
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.
Strong evidence from clinical studies backs this claim.
When you curl with your arms behind you, your biceps stretch more and grow more than when you curl with your arms in front.
Evidence contradicts this claim.
When people lift weights through a full motion vs. just part of the motion, the muscles might look like they grow more in one case—but that could just be because the weight feels heavier at different points, not because the muscle is stretched more. So we can’t be sure if stretching the muscle is what’s causing the growth.
Multiple causal studies (randomized trials and reviews) support this claim.
Holding a muscle stretched while pushing against something still makes it grow more than holding it short, even if you don’t move.
Evidence points in both directions — no clear conclusion yet.
Some muscles might respond differently to how you stretch them during exercise, depending on how they’re built.
Not enough evidence yet — take this with caution.
Resistance training with muscles stretched further may lead to different muscle growth outcomes in people who are new to training versus those who are experienced, but there is not enough reliable data yet to know for sure.
Multiple causal studies (randomized trials and reviews) support this claim.
The amount of training, how hard you train, and how regularly you train have a greater impact on muscle growth than whether your muscles are stretched or shortened during exercise.
Multiple causal studies (randomized trials and reviews) support this claim.
Key Takeaways
Summary
Based on the video transcript only.
- 1Problem: 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.
- 2Core 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).
- 3How 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.
- 4Expected outcomes: Both sides grew the same amount—no difference in muscle size between training with peak difficulty at long vs. short muscle lengths.
- 5Implementation timeframe: Results were seen after 10 weeks of training twice per week.
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