Broken legs and ankles heal better if you walk on them within weeks

from https://www.outsideonline.com/health/training-performance/fo...

    ... After a heroic research effort that took 2.5 years and 500,000 euros, he and his colleagues had managed to shepherd a large group of frail, elderly subjects through a six-month strength-training program. Those who had taken a daily protein supplement managed to pack on an impressive 2.9 pounds of new muscle. Success! Old people could be strong!

    ... On his phone was a photo one of his students had just sent him of a large plate stacked high with bulging cubes of raw beef. In total, there were 3.1 pounds of beef—a graphic visualization of the muscle lost in just one week by subjects of a bed-rest study the student had just completed.

    “I usually put this in more obscene language,” van Loon says, “but you can mess up a lot more in one week than you can improve in six months of training.”

Some good videos on Starting Strength of what they have done for older people: https://www.youtube.com/watch?v=ekJOT0kn5vs (Such as the 86 year old lady in the video).

> In total, there were 3.1 pounds of beef—a graphic visualization of the muscle lost in just one week by subjects of a bed-rest study the student had just completed.

This is significantly out of line with other research I've seen. Marusic et al. (2021) meta-analysis[1] found an average muscle loss of ~2% after 5 days. It did not report average absolute muscle loss, but the average person has about 1/3 of bodyweight as muscle, so at an average weight of ~180 pounds, that would represent 1.2 pounds of muscle loss in a ~week, not 3.1 pounds.

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC8325614/

The meta-analysis study you cite suggests 2% loss @ 5 days and 5% loss at 10 days at the knee extensor muscles.

Notice that percentage loss is more than double for a doubling of bedrest time. It's not linear.

You're suggesting that muscle loss at the knee extensor is the same percentage for the rest of the body.

from the full text of the bedrest study mentioned in the outsideonline.com article - muscle loss was measured via DXA scan. see https://diabetesjournals.org/diabetes/article/65/10/2862/350...

    After 1 week of bed rest, participants lost 1.4 ± 0.2 kg (range: 0.6 to 2.8 kg) lean tissue mass (Fig. 1A) (P < 0.01), representing a 2.5 ± 0.4% loss of lean tissue mass.