How long does it take to start losing muscle if you’ve stopped working out because of injury?
Injury usually puts a muscle to rest—and rest isn’t good for muscles. Research shows that a person at bed rest can lose about 20% of their muscle strength and muscle mass in just one week.
The clinical example we often use is an athlete who’s placed in a knee immobilizer on Friday night for an injury then rechecked on Monday. The circumference of the quad above the knee will have shrunk considerably.
Top tip: If you can move your muscles without pain, do at least a few minutes of light exercise every day.