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Body System

Muscle

Strength, recovery, and skeletal muscle performance.

Last reviewed
July 2026
Version
1.0
Review cadence
Annually

Overview

Skeletal muscle powers movement, but it is also a metabolic organ — a store for glucose, a driver of insulin sensitivity, and a key determinant of strength, independence, and healthy aging.

Why it matters

Muscle mass and strength predict function and mortality, and both decline with age unless actively maintained. Preserving muscle is one of the highest-yield investments in healthspan.

Start Here

New to this? Read these first

  1. FoundationResistance TrainingWhy strength training is one of the highest-yield things you can do for lifelong health.
  2. ConditionSarcopeniaAge-related loss of muscle strength and mass
  3. BiomarkerIGF-1The downstream marker of growth-hormone activity
  4. Signal RecordNSAIDsIbuprofen, naproxen, diclofenac — and why there is no safe one
  5. Body SystemBone
Typical Journey

How this usually unfolds

  1. Understand the system
  2. Know the key biomarkers
  3. Learn the common conditions
  4. Apply evidence-based interventions

An orientation to how this topic is typically approached — not medical advice.

Major functions

  • Movement and force production
  • Posture and joint support
  • Glucose disposal and metabolism
  • Protein reserve
  • Heat production

Common conditions

Evidence-based

Prevention

  • Strength train across the lifespan
  • Eat adequate protein
  • Stay active daily
  • Avoid prolonged bed rest
Evidence-based

Improvement strategies

  • Progressive overload resistance training
  • Protein distribution across meals
  • Creatine (well-evidenced)
  • Managing underlying illness
Explore

Explore this system across BioSignal

Related body systems

Related lifestyle interventions

  • Progressive resistance training
  • Adequate protein intake
  • Sufficient total activity
  • Recovery and sleep

Related diagnostics

  • Strength and grip testing
  • Body composition (DXA)
  • Testosterone / IGF-1 (context)
  • VO₂ max

Frequently asked questions

How much protein do I actually need?

Many healthy, active adults do well toward the higher end of common recommendations, distributed across meals. See the Protein Intake Foundation for the evidence.

Is it too late to build muscle in older age?

No. Older adults respond well to resistance training and protein; it's one of the most effective ways to protect independence.

Educational information — not medical advice

Body System hubs orient you across the evidence; they don't diagnose or treat. Interpret your own health with a qualified clinician. See our Medical Disclaimer.

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