For people who are already trained, lifting weights with muscles stretched out does not result in more muscle growth than lifting with muscles shortened, and it does not result in less muscle growth...
Mechanism
Synthesis from 5 studies
Stretching a muscle under load creates tension that turns on a built-in growth signal inside muscle cells. This signal tells the cells to make more muscle proteins, making the fibers bigger. Whether you stretch the muscle fully or only partially, as long as it's under tension while stretched, the...
Most probable mechanism
When a muscle is stretched under load, the fibers and surrounding structures experience increased tension. This tension triggers a biochemical signal inside the muscle cells that turns on the machinery responsible for building new muscle proteins. The added proteins increase the size of the muscle fibers, leading to growth. This process works just as well whether the muscle is stretched through a full range or only partially, as long as the stretch and tension are maintained.
Muscle fibers are held at or near their longest physiological length during resistance exercise, increasing passive tension in sarcomeres and extracellular matrix.
Elevated mechanical tension activates the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway.
Activated mTORC1 increases ribosomal biogenesis and enhances the rate of muscle protein synthesis.
Net accretion of contractile proteins (actin and myosin) increases muscle fiber cross-sectional area, resulting in measurable hypertrophy.
Less supported by current evidence, but not ruled out
When a muscle is stretched under load, the region closest to the tendon experiences greater strain, which triggers localized protein buildup in that area. This causes uneven growth, with more thickening near the tendon than in the middle of the muscle.
Distal muscle regions experience higher strain gradients during prolonged stretch due to their proximity to tendon insertion points.
Localized mechanical stress increases satellite cell activity and myonuclear accretion in the distal muscle region.
Accumulated protein synthesis in the distal region increases fascicle cross-sectional area, measurable as increased muscle thickness at distal sites.
Evidence from Studies
Supporting (5)
Community contributions welcome
The Effects of Long Muscle Length Isometric versus Full Range of Motion Isotonic Training on Regional Quadriceps Femoris Hypertrophy in Resistance-Trained Individuals.
Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women
Contradicting (0)
Community contributions welcome
Gold Standard Evidence Needed
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