Why Aging Muscles Shrink — And How to Stop It
In a Nutshell
Aging muscles paradoxically overactivate mTOR, the growth signal, which blocks autophagy and causes junk buildup, leading to sarcopenia despite higher growth cues—suppressing mTOR (as shown in fly and mouse studies) restores muscle quality and function. Exercise spikes mTOR short-term for growth but lowers chronic overactivation long-term, rejuvenating muscles molecularly while enabling inter-organ signaling for broader health benefits like higher NAD levels. Key strategies: resistance training, ample protein, 5g daily creatine monohydrate, 0.5g sarcosine, 1.5-2g omega-3s, and 500-1000mg oleuropein to combat muscle loss.
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Muscle loss with age affects mobility, metabolic health, and independence. Advice is to build muscle, lift weights, eat protein. Paradox: in aging muscle, the build and grow signal is higher, yet muscle shrinks.
Chapter 1: Aging muscle paradox, new findings, why they make sense. Chapter 2: How exercise makes muscles young while building them. Chapter 3: Muscles are much more than mechanical. Chapter 4: High-yield strategies for muscle health with aging.
References, extra nuance in Stay Curious Metabolism newsletter.
Paper in Proceedings of the National Academy of Sciences.
mTOR is a protein complex that positively regulates growth pathways, the big red go button for growth, critical for building muscle.
In aging muscle and sarcopenia (age-related muscle wasting), mTOR activity is higher, not lower. Older adults show higher mTOR expression.
Paradox: older muscles slam the muscle growth button but waste away.
mTOR promotes growth but suppresses cellular recycling (autophagy), which clears damaged proteins and dysfunctional components.
Chronically elevated mTOR stalls cleanup, causing accumulation of molecular junk, dysfunctional proteins, increased biomarkers of cellular senescence.
mTOR is a double-edged sword: promotes growth, blocks renewal. In aging muscle, chronic mTOR overactivation leads to quality deterioration; molecular damage overpowers growth, muscles waste away.
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