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Glossary

Mechanostat

Defined in topic 6

H.M. Frost's model in which bone remodels itself to the loads placed on it, sensed by cells called osteocytes. The loop runs for life, so bone is lost within months when loading stops.

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Where this comes from

In the reference topic that owns this term

Reference topic 6, The Sitting Disease, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

Hours of walking and carrying, and rest in postures (squatting, kneeling, ground-sitting) that keep leg muscles working.

What it gets

About 7.7 sedentary hours a day for the average American, and too little activity for nearly a third of adults worldwide.

What happens in the gap

Higher blood sugar after meals within hours; lost fitness within weeks; bone loss within months when loading stops, and lighter skeletons over millennia; higher mortality where long sitting meets low activity.

The full card, and the topic behind it

What that chapter recommends

3 of the 7 graded recommendations in Reference topic 6, strongest evidence first. How the grades work.

  1. Break up long sitting

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Every 20-30 minutes, walk for 2-5 minutes; walking beats standing. ●●○ (consistent short trials; long-term benefit unproven)

    Read it in full

  2. Move enough to cancel the chair

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    About 30-40 minutes a day of moderate-to-vigorous activity (measured by motion sensor) weakens the link between long sitting and early death. By questionnaire, 60-75 minutes of moderate activity appears to erase it. ●●○

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  3. Take the stairs

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Climbing more than five flights (about 50 steps) a day was associated with 16-23% lower risk of atherosclerotic cardiovascular disease (disease of clogged arteries) in 458,860 UK adults.

    Read it in full

Related terms

The argument behind this term, its studies and its notes are in Reference topic 6 of the reference library. The book gives the practical version. Get the book.