Is soreness a sign of a good workout?
No: soreness tracks novelty and eccentric loading, not growth.
You can get very sore from a new exercise or a lot of lowering work, and you can grow steadily for months with little soreness once your muscles are used to the training. Track load, reps and sets instead; those tell you whether you are progressing.
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- Damas, F. et al. (2016). Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage. J Physiol 594(18). Early responses dominated by muscle damage did not track later growth.
- Schoenfeld, B.J. & Contreras, B. (2013). Is postexercise muscle soreness a valid indicator of muscular adaptations? Strength Cond J 35(5). Argues directly against using DOMS as a progress marker.