Training
Do I need to be sore after a workout?
Direct answer
No. Muscle soreness isn't a requirement for an effective workout.
Explanation
When you first start training, return after some time away or introduce something your body isn't used to, you're more likely to experience muscle soreness in the following days.
As you consistently perform similar training, your body adapts and that soreness will often reduce. That doesn't mean the exercise has stopped working or that you need to keep changing your programme just to make yourself sore again.
You can also experience more soreness after increasing your training volume, introducing a new exercise or placing a muscle under stress in a way it isn't currently accustomed to. Again, that tells us you've exposed the muscle to something different, but it doesn't automatically tell us how productive the workout was.
How to apply this
Judge your training primarily by what you're actually doing and how you're progressing, rather than how sore you feel the following morning.
Look at things such as your technique, the effort you're putting into your working sets, the weight and repetitions you're performing and how these progress over time.
Some soreness is completely normal, particularly when your training changes.
It just shouldn't be the target of the workout.