Bed rest Flashcards
Review of the effect of bed rest and how PA affects bed rest
How does bed rest affect MSK function?
Causes atrophy after just a couple days of immobility
Why does atrophy occur?
Polypeptide synthesis is decreased (by ~50%), and muscle pp breakdown increases because of changes in: muscle cell signalling; gene expression at mRNA and pp levels; polypeptide biochemistry; proteasome and protease activity
What muscle groups experience greatest muscle atrophy?
Muscles for standing and walking
How does bed rest affect skeleton function?
Causes loss of bone mineral density
Why does loss of bone mineral density occur?
Bones not performing normal weight-bearing functions, leading to deterioration of cartilage and muscles shortening
How does a short bed rest affect CV function?
Increased heart rate, decreased blood volume (decreased blood O2 carrying capacity, plasma volume, and RBC mass), decreased cardiac output
How does a long bed rest affect CV function?
Blunted vasodilator function, cardiac atrophy, decreased peripheral O2 diffusing capacity
What is the relationship between VO2max and time spent in bed rest?
Linear relationship; 0.3% decrease in VO2max/day; 0.008l/min/day
How is prestudy VO2max related with change in VO2max after a period of bedrest?
Inversely associated
How do you minimise negative effects of bed rest?
Physical therapy (ASAP, within 48 hours), orthostatic pressure gradients, exercise training
What are the effects of physical therapy for bed rest?
Decreases ICU and hospital stays, increases number of ventilator-free days, increases peripheral and respiratory muscle strength, increases physical function, increases function status and quality of life
What are the implications of a microgravity environment?
Experience decreased loading, decreased hydrostatic gradients, and altered neurovestibular system
What does decreased loading cause?
Muscle atrophy, decreased mineral density, altered metabolism
What does decreased hydrostatic pressure cause?
Decreased CV load, as blood no longer pooled in lower limb, so heart does not have to work against gravity, causing heart to be weaker when return to Earth
