Bedrest was the standard prescription in the 1950s. A Cochrane overview of 381 studies points the other way. What that means for a program when something hurts.
In the 1950s the standard medical prescription for a painful back was bedrest. Weeks of it. The logic felt obvious: something hurts, so protect it until it stops hurting.
The research since has gone the other way, comprehensively.
What the evidence says
The largest summary of the question is a Cochrane overview that pulled together 21 systematic reviews on exercise and chronic pain: 381 studies and more than 37,000 people, across conditions from low back pain to arthritis (Geneen et al., Cochrane, 2017). Across those reviews, exercise tended to reduce pain severity and improve physical function. The reported downsides were mostly temporary muscle soreness that settled within weeks.
The fair read on that evidence is that much of it is low quality. Most of the underlying studies were small, most participants had mild to moderate pain, and follow-up periods were short. The effect sizes deserve some caution. What the evidence does not show, anywhere, is that resting a sensitive body makes it more robust.
For acute low back pain specifically, a separate Cochrane review compared the old advice directly against the new. People advised to stay active recovered slightly better, in both pain and function, than people advised to rest in bed (Dahm et al., Cochrane, 2010). The bedrest era ended because the data ended it.
What pain is measuring
Pain is the nervous system's estimate of threat. It is a poor measure of tissue damage, and the amount of pain is a weak guide to the amount of harm. A sensitive shoulder can be a structurally sound shoulder. Sensitivity calls for intelligent loading, and rest on its own rarely provides it.
One thing worth saying plainly. Muscles get pulled reaching for luggage, gardening, and sleeping at a strange angle. A tweak is evidence that you have a body. The people who stay strong for decades still feel things. They keep training around them.
The sensible caveat stands. Sharp pain, numbness, or pain that is not settling deserves proper assessment. Working out what is safe to load, and how, is clinical work.
What this looks like in practice
This is the core of exercise physiology. A cranky shoulder, a tight hamstring, a knee that complains on the stairs: each one gets reported, assessed, and the program gets modified the same session. Pressing moves around a shoulder. Hinging moves around a knee. Training continues while the sensitive part settles, and the rest of the body keeps its momentum.
At ZAR, every program is written and adjusted by an accredited exercise physiologist. Report anything. Working around it is exactly what the programming is for.
References
Geneen LJ, Moore RA, Clarke C, Martin D, Colvin LA, Smith BH. Physical activity and exercise for chronic pain in adults: an overview of Cochrane Reviews. Cochrane Database of Systematic Reviews. 2017. DOI: 10.1002/14651858.CD011279.pub2
Dahm KT, Brurberg KG, Jamtvedt G, Hagen KB. Advice to rest in bed versus advice to stay active for acute low-back pain and sciatica. Cochrane Database of Systematic Reviews. 2010. DOI: 10.1002/14651858.CD007612.pub2