Mixed
Step reduction (SR) to <1,500 steps/day for two weeks causes significant declines in muscle protein synthesis (MPS), leg lean mass, and insulin sensitivity in older adults, with incomplete recovery upon return to habitual activity.
If you are older, do not underestimate the impact of even mild inactivity, such as reducing your steps to under 1,500 per day for a couple of weeks due to illness or weather. This causes your muscles to stop building protein and your blood sugar control to worsen. Crucially, your body may not fully bounce back to its previous state even after you start moving normally again. To protect your muscle, try to maintain your usual step count even during minor illnesses or bad weather, or use countermeasures like light resistance exercise and high-quality protein.
Consistent with the concept of muscle disuse-induced 'anabolic resistance'... work from our laboratory has shown consistent reductions in MPS in response to 2 weeks of SR of varying degrees (750–1500 steps per day)... with rates reduced 13–26% from baseline... the reduced rates of MPS seen during inactivity were not recovered following 2 weeks of return to habitual activity.
Why this rating
Based on multiple controlled human studies (McGlory, Breen, Oikawa) cited in the review, though the paper itself is a review.
Source
The Impact of Step Reduction on Muscle Health in Aging: Protein and Exercise as Countermeasures
Sara Y. Oikawa et al. · Frontiers in Nutrition · 2019
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