Why Muscles Grow Bigger Without More Muscle Power
Muscle fiber hypertrophy in response to 6 weeks of high-volume resistance training in trained young men is largely attributed to sarcoplasmic hypertrophy
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When strong young guys lift weights a lot for 6 weeks, their muscle fibers get bigger, but not because they add more muscle-building proteins. Instead, the inside fluid and energy-making parts of the cell grow more.
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Systematic Reviews & Meta-Analyses
Max 100Randomized Controlled Trials
Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
Max 44Case Reports & Case Series
Max 30Expert Opinion & Narrative Reviews
Max 539 / 72
Evidence Score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When strong young guys lift weights a lot for 6 weeks, their muscle fibers get bigger, but not because they add more muscle-building proteins. Instead, the inside fluid and energy-making parts of the cell grow more.
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Systematic Reviews & Meta-Analyses
Max 100Randomized Controlled Trials
Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
Max 44Case Reports & Case Series
Max 30Expert Opinion & Narrative Reviews
Max 539 / 72
Evidence Score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Publication
Authors
Haun CT, Vann CG, Osburn SC, Mumford PW, Roberson PA, Romero MA, Fox CD, Johnson CA, Parry HA, Kavazis AN, Moon JR, Badisa VLD, Mwashote BM, Ibeanusi V, Young KC, Roberts MD
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Claims (8)
Even the muscles that are built for endurance can get bigger—like, over 10% bigger—if you do the right kind of strength training for a few months. This goes against what people used to think.
When young guys who already work out do a lot of high-volume weight training for 6 weeks, their muscles grow mostly because of fluid and non-contracting parts inside the muscle cells, not because they’re building more of the actual muscle-building proteins — and this change sticks around for over a week after they stop training.
When young guys who already work out do a lot of high-rep weight training for a short time, their muscles get bigger but their energy-producing parts actually become less dense, meaning bigger muscles don’t always mean more energy factories inside them.
Lifting heavy weights for six weeks changes specific proteins in the muscles of fit young men. This suggests their muscles are switching to a way of making energy that doesn't require oxygen.
After young guys stop intense weight training, their muscle proteins stay low for over a week, suggesting it's not just temporary swelling or soreness.