Injured? There’s almost always a work around to continue some kind of exercise.
If you have a knee injury, focus on hip hinging exercises to continue to fire your lower body muscles without inflaming the knee.
You may also train the uninjured side with single leg movements (like quad extensions, ham curls etc) to take advantage of ‘reciprocal innervation’. This means that there will be some bilateral firing of the nerves.
While impact exercises like running may be out, you can likely ride a stationary bike & do KB swings to get your heart rate up.
Here are just a few of the exercises you can do…
•Romanian deadlift (RDL) both single & double leg
•glute bridges & variations
•donkey kicks & variations
•fire hydrant variations
•leg lifts (not pictured)
•calf raises (not pictured)
What have I missed?