John Barban answers the question on training if your muscles are sore. The short answer is that “it depends”.
Cliff notes from his post:
- Range of motion test: If you can’t perform movements with a regular full range of motion, take another day off.
- Strength test: If you can’t hit your normal rep range for the first set or two of a lift, then wait another day before training.
- Soreness on a scale of 1-10: You should aim to be at a 4-5 before you train. If you are an 8-10 precieved soreness, then wait a day or two before training.