"To rest or not to rest" - that is NOT the question
Many injuries require some degree of off-loading. However, there are few where complete and total rest is indicated. Getting the load right is one of the most important factors in recovering from musculoskeletal injury. But for most injuries, total load (as in volume and intensity) is far less important than the TYPE of load.
Here are a few examples.
Tendons tolerate complete rest at least as poorly as they tolerate sustained overuse. Degenerative tendons require regular non-aggravating loads to stimulate repair. They are more tolerant of continuous load than a brief spike in load. Put simply, tendons are easily aggravated when they are asked to behave like a spring. Think jumping versus cycling. Cycling can require very high loads in terms of magnitude and volume but the sustained, non-springy nature of the load is tolerated much better than the springy impulsive load of jumping.
Bone fractures in areas under compressive load generally heal far better than fractures in areas subjected to tensile loads. The anterior tibial cortex (more tensile load) has a high rate of delayed or non-union whereas the posterior cortex (higher compressive load) is extremely resilient. The superior neck of femur is far more problematic than the inferior aspect for the same reasons. Bone that is off-loaded too aggressively for too long risks the development of “disuse osteopaenia” (which is transient low bone strength) and often stress fractures occur. The key to healing stress injuries in bone is understanding the optimal load for the location and grade of injury.
I can’t think of a single condition where the type of loading is more critical yet so difficult to get exactly right. Osteitis pubis is an extremely complicated syndrome that results from excessive sheering force across the pubic symphysis. There are conflicting agendas in resting enough from aggravating activities to allow the inflammation and bone stress to settle down at the symphysis but exercising enough to strengthen the muscles that maintain stability across the joint. Far too often rest is too aggressive and the loss of strength severely aggravates the problem. But going into detail about ‘O.P.’ is an entire blog for another day.