Effect of Lung Disease on Muscles

• Effect of Lung Disease on Muscles - These are CT scans of the mid-thigh:

  • muscle atrophy
  • increase in adipose (fat tissue

  
• Effect of Lung Disease on Muscles - This is a graph of the relationship between exercise capacity (6MWD) and disease severity (FEV1% predicted):

  • increase in FEV1 = slight increase in 6 minute walk distance
  • levels off
  • large variation in results of the same FEV1 score compared to distance

  
• Effect of Lung Disease on Muscles:

  • Lower limb muscles especially the quadriceps are affected
  • Preservation of upper limb strength
  • Majority of research has been done in COPD
  • Likely similar effects in other respiratory diseases
  • change from type 1 muscles fibres to type 2 - increase in fatigue
  • mitochondrial dysfunction - low energy, increase in fatigue
• Effect of Lung Disease on Muscles: Mechanism - poorly understood:

  • Disuse and deconditioning
  • Inflammation
  • Malnutrition
  • Oxidative stress - due to mitochondrial dysfunction
  • Hypoxia
  • Hypercapnia
  • Steroids
  • Low levels of anabolic hormones and growth factors
  • Vitamin D deficiency
• Effect of Lung Disease on Muscles: Cycle of Inactivity:

  1. breathlessness
  2. inactivity
  3. muscle weakness
  4. inefficient muscles
  5. cardiovascular deconditioning (leads back to breathlessness)
• Effect of Lung Disease on Muscles: Impact

  • Breathlessness
  • Difficulties doing activities of daily living (ADL)
  • Physical inactivity
  • Exercise intolerance
  • Poor quality of life
  • Premature mortality