Up to 5 out of 10 that settles within an hour, no more swelling the next morning, and 3 out of 10 for a growing heelEmerging evidence
Some discomfort during exercise is fine. Aim for pain you would call mild to moderate, no more than about 5 out of 10, that settles within an hour, with no more swelling or stiffness the next morning. If it's worse the next day, do a little less (a smaller range, fewer reps, a lighter band), not nothing.
The exceptions: pain in one spot on a bone should be pain-free, because it could be a stress fracture; burning, tingling or numbness means stop that movement; and if your feet are numb, pain won't warn you, so check your skin after exercise.
If pain climbs day after day, or you notice a warning sign, stop and get it checked. The 5 out of 10 figure is an editorial starting point that matches this site's other pain guides, not a tested rule.
After a sprain, NHS hospital leaflets say the exercises should not increase your pain, and gentle exercise from the first week was safe in a trial: re-injury was 4% with or without it.
Two positions are different. Early on, don't force the foot to turn outwards (pivoting or cutting on a planted foot) or to bend up hard (deep squats or lunges, with the knee pushed far over the toes): that's how the injury happens, and the rehab review avoids both until the second phase, then moves through the full range gently.
Move on by milestones, not dates: walking without crutches and with little discomfort; then jogging and hopping without pain or giving way; then sport drills at game speed with little or no pain. After surgery, your team's limits on weight and movement come first.
This site's suggested rule: pain during exercise up to 5 out of 10, back to its usual level by the next morning, and not creeping up week on week. If it is worse the next morning, lighten the load for a few sessions rather than stopping.
Bending the ankle up under load (squats, lunges, stairs, the knee-to-wall rock, landings, plié): stay short of the sharp pinch at the front of the ankle. A stretch in the back of the calf is fine; a pinch at the front is not. Let the depth come back over weeks (our suggestion).
NHS Lothian's Royal Hospital for Children and Young People says pain during activities should be no more than 3 out of 10, where 0 is no pain and 10 is severe pain. A little discomfort during the exercises is normal as long as it settles after stopping, and on the way back to sport, a little pain is OK if it settles quickly after exercise.
Check during sport, straight after and the next morning, and if the heel is sorer the next day, cut back for a few days (both our suggestions). A Cambridge NHS leaflet adds that the pain may take longer to settle if your child keeps playing, and children's physiotherapists suggest a complete break for a while only if pain stays severe.
For football (our suggestion, built on the rules above, the brace and balance trials and the return-to-play advice of the AAOS and the AOSSM): judge each session or match by the ankle during it, that evening and the next morning. Up to about 5 out of 10 that settles within an hour, with no more swelling the next morning, is fine for strength, balance and running drills. Hops, cuts, tackles and shooting come back only when they cause little or no pain and no giving way, as the milestones above say; wear the brace or tape for training and matches after a sprain. A growing player's heel keeps to 3 out of 10 during play. One spot on a bone that hurts, a roll that swells fast, a snap at the back of the heel or a hot, red ankle isn't a pain-rule question: see the warning signs.
Sources 61, 62, 47, 63, 34, 31, 58, 46, 88, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 76, 77
