The short answer
- First decide whether this needs a person or a plan. A short list of patterns means get it looked at rather than manage it yourself.
- If it is not on that list, you almost certainly do not need complete rest, and complete rest is what most people reach for.
- The question is what dose of running leaves you no worse the next morning. That is usually more than zero.
- Skip the scan. In the first week it mostly finds things that were already there.
- Write down what you did and how it felt the following morning. Three entries will tell you more than three days of worrying.
Something hurt on today's run and now you are on your phone at eleven at night. I know how this goes. Most of the searching you are about to do will not help, so here is the short version of what the first three days are actually for.
First, the sorting question
Before anything else, work out whether this is a plan or a person.
Nothing on that list is common. If none of it applies, you are in ordinary territory and the rest of this page is for you.
What not to do
Stop everything and rest completely. That is the instinct and it is usually wrong.
Tissues need load to adapt. Three weeks of nothing lowers what your body is prepared for, so when you come back the same run is now too much, and the injury that would have taken a fortnight takes two months.
Buy a treatment in the first 48 hours. Almost nothing you can purchase in the panic window changes the trajectory of a running injury.
Get a scan. In the first week it mostly finds things that were there before. Degenerative changes turn up in large proportions of people with no symptoms at all, in knees1 and in spines2, and a finding on a report is not by itself the cause of your pain.
Change five things at once. If you swap your shoes, add three exercises, cut your mileage in half and start stretching, and it improves, you have learnt nothing about which part helped.
The rule that replaces resting
1During the run, it stays at five out of ten or below.
2By the next morning, it is back where it started.
The second rule does almost all the work. A run that hurt a four and is gone by breakfast is a run you can repeat. A run that hurt a two and is still there thirty-six hours later is not, whatever the number was at the time.
This is also why the first 72 hours are less decisive than they feel. You need a couple of runs and a couple of mornings to find your level, and that takes days.
What to actually do
Work out which sessions provoke it most, and edit those first. For most injuries that is not the total distance. Hills, speed and downhills provoke far more than easy flat running, and cutting those keeps more of your week than halving everything does.
Keep the easy running that passes the rule above.
Start the strength work now rather than later. There is no reason to wait for the pain to settle before beginning to raise capacity, and waiting is how people end up rehabbing for three months instead of six weeks.
Write it down. Date, what you did, pain during out of ten, how it felt the next morning. Three entries and a pattern appears.
What the first week is not
The outcome of most running injuries is decided over weeks, by what you do repeatedly, not by what you do in the first 72 hours.
In the trial of runners with kneecap pain, the arm that got education on managing training loads did as well over eight and twenty weeks as the arms that added exercises or gait retraining4. The load plan was doing the work, and a load plan is something you run for months.
So: no, you have not ruined your season by running on it today. And no, doing something dramatic tonight will not rescue it either.
When to stop waiting
Six weeks of genuinely modified running and honest strength work, with no change at all, is the point to ask someone rather than continue.
Getting worse despite doing less is a different signal and does not need six weeks.