It is common for athletes to modify workouts when injured to just use one leg or one arm with different movements. For example, using one leg instead of two on the rower or doing dumbbell snatches all on one side. While this is not wrong to do it is not a method I like or recommend.
And here’s why…
When only training one side, you can develop both movement pattern asymmetries as well as strength asymmetries.
Movement asymmetries: Without intending to, when only pushing or pulling with one side of the body on different movements, you may teach the body to start moving in those types of patterns regularly. For example, with single leg rowing, it is possible your body creates a habit of pushing with that side and not the other. Once you recover and start to row, deadlift, or squat, you may bias the leg you have been using rather than using them equally. Using only one side can also create rotational patterns that were unintended. For example, when doing a snatch, your body rotates slightly through that motion. If you use your right arm consistently with the movement, your body may create new patterns for that direction. These compensated, learned patterns are hard to break once they are created.
Strength asymmetries: Any time you only train one side, you are going to develop strength asymmetries. When you do this when one side is injured, you are making it even more asymmetrical. While these can level out over time when you start using the injured side again, it will take a lot longer to even out than it would have if you would not have trained only one side.
Create new injuries
I have seen quite a few instances of training in this method creating new injuries, more specifically, injuries on the side that was not injured. Only training one side basically creates an overtraining scenario on the side that is being worked. Overtraining situations often result in injuries. Unfortunately, these injuries are not usually noticed immediately, which is why people likely do not see a problem with doing it. These issues are often noticed later, once normal training has resumed. My thoughts on the reason is that you went from training single side to both sides, never giving the non-injured side a rest.
Curious what to do instead? Glad you asked!
Find movements you can keep symmetrical. What that looks for each person will be different based on the injury, but that could include decreasing the range of motion, decreasing the weight, not using the legs (ie: legless rowing, seated ski-erg, seated wall balls), not using the arms (ie: squats instead of thrusters), or completely changing movements
Have specific questions on what you can do? Email them to firstname.lastname@example.org.