I'd think 48 hours is plenty of time for muscles to rebuild given the right diet.
Not to argue, but this really does depend on how far you tear down the muscle. If you train to failure, or near failure with many sets (4x10, for example) you will not recover in 48 hours unless you are in the prime of your life (18-22 maybe) and are a special person or have special medications
🙂DDDD)
I know a heavy deadlift session would take over a week to recover from where my strength levels are back to where they were before I did the set. I did 315 for 12 reps, not even failure and I was sore for about 5 days. Now, DOMS is also debated heavily, but most agree it is the tearing of the muscle fibres as it generally hits the eccentric portion of the lift, where the tears are likely to happen. Thus, I think it is fair to say that if you still have DOMs, you are not recovered.
With that said, trainign through DOMs can also train the body to recover faster and adapt faster. So, this is one of those chicken or egg thigns.
I know for Neck training, there was some research that suggested most men gained pre-workout strength back in their necks from 72 hours to 1 week depending on the guy. The neck has plenty of bloodflow, so it would heal faster than pretty much any other muscle group. If the neck takes between 72 horus and 1 week, it is safe to assume that would also apply other muscle groups. Just throwing this out there.