The 5 out of 10 rule, the arm-symptom exception, and turning only as far as is comfortableEmerging evidence
For the exercises, this guide uses the neck hub's rule, from NHS inform's neck exercise advice: rate your pain from 0 to 10. During exercise, 0 to 3 is minimal and 4 to 5 is acceptable; 6 or more is too much. If it goes higher, do fewer repetitions, move more slowly or rest longer between movements.
Exercise should not make your neck worse overall. Soreness from a new exercise should ease quickly, and your neck should be no worse the next morning. Stop any exercise that makes your symptoms worse or causes new pain.
Arm symptoms are the exception, as in our neck pain guide: if an exercise sends pain, tingling or numbness further down your arm, or the extra symptoms last more than an hour afterwards, make the movement smaller or leave it out. Stop and get checked for dizziness, double vision, slurred speech, trouble swallowing or any of the warning signs.
In the pool (our suggestion): turn to breathe only as far as is comfortable, using more body roll, and swim backstroke or use a snorkel if you need to.
In the pool, this guide's rule is adapted from one expert commentary written for competitive swimmers coming back after shoulder surgery, so treat it as a sensible guide rather than a tested rule. If the sore area is back to its usual level by the next morning, the next swim can be the same or a little longer.
Soreness that lasts more than an hour after swimming, or into the next day: take a day off swimming, then repeat your last session rather than adding to it. Sore in the warm-up but gone within the first few hundred metres: repeat the same session, and if it comes back during that swim, stop, take 2 days off and come back a little shorter (the protocol cuts 300 yards, about 275 m). Sore in the warm-up and still sore after the first few hundred metres: stop for the day, take 2 days off and come back a little shorter.
Sources 20, 26