Where you hold your muscle workout changes how it grows
Differential changes in muscle architecture and neuromuscular fatigability induced by isometric resistance training at short and long muscle-tendon unit lengths.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
People did leg exercises holding their muscle stretched out vs. bunched up for 8 weeks. One way made muscle fibers longer; the other made them thicker and angled. Neither way made people much less tired, but the changes in muscle shape were linked to how tired they felt.
Surprising Findings
Increased fascicle length (from stretching) correlated with *worse* fatigue resistance (r = -0.568), while increased pennation angle (from shortening) correlated with *better* fatigue resistance (r = 0.739).
Common belief: longer muscle fibers = more endurance. But here, longer fibers were linked to *faster* fatigue. Meanwhile, the angled structure (often seen as just for force production) showed a strong link to endurance.
Practical Takeaways
If you want to maximize muscle architecture changes, try isometric holds at both long and short lengths—stretching for fiber length, shortening for pennation angle.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
People did leg exercises holding their muscle stretched out vs. bunched up for 8 weeks. One way made muscle fibers longer; the other made them thicker and angled. Neither way made people much less tired, but the changes in muscle shape were linked to how tired they felt.
Surprising Findings
Increased fascicle length (from stretching) correlated with *worse* fatigue resistance (r = -0.568), while increased pennation angle (from shortening) correlated with *better* fatigue resistance (r = 0.739).
Common belief: longer muscle fibers = more endurance. But here, longer fibers were linked to *faster* fatigue. Meanwhile, the angled structure (often seen as just for force production) showed a strong link to endurance.
Practical Takeaways
If you want to maximize muscle architecture changes, try isometric holds at both long and short lengths—stretching for fiber length, shortening for pennation angle.
Publication
Journal
Journal of applied physiology
Year
2020
Authors
R. Akagi, Avery Hinks, Geoffrey A. Power
Related Content
Claims (6)
Doing 8 weeks of strength training with your muscle either stretched or bunched up doesn’t make you much better at resisting fatigue — the improvement is very small and not clearly real.
Doing strength exercises with your muscle stretched out for 8 weeks can make the muscle fibers longer, but doing them with your muscle bunched up doesn’t change their length.
Doing strength exercises with your muscle bunched up for 8 weeks can make the muscle fibers angle more sharply, which might help them generate more force.
When people train with their muscles bunched up, the more their muscle fibers angle upward, the longer they can keep pushing hard before getting tired.
When people train with their muscles stretched out, the longer their muscle fibers get, the more quickly they tire out during repeated efforts.