Reading time: 5 Minutes
MWi Hack:
- The next time something hurts during training, don’t make the call in the moment. Check it the next morning instead. The current Achilles tendinopathy clinical guideline uses three criteria: pain at or below 5 out of 10 during the session, no flare the following day, and no disruption to your sleep. Meet all three and the load was right, so repeat it. Miss one and you drop the load rather than stopping altogether. One check, once a day. It replaces guessing with a number.
MWi Summary:
- An updated systematic review in the Journal of Orthopaedic and Sports Physical Therapy, published August 2025, found no clear advantage either way between painful and pain-free exercise for musculoskeletal pain. Pain during exercise does not have to be avoided for people to improve.
- That finding cuts in both directions. Driving into serious pain buys nothing, and shutting down all movement because something hurts costs a great deal.
- The revised Achilles tendinopathy clinical practice guideline, published in JOSPT in 2024, sets the monitoring standard at pain no higher than 5 out of 10 during exercise, no next-day flare, and no disruption to sleep.
- The 24-hour check is the real test. Pain or morning stiffness the same or better the next day means the load was tolerated. Higher means the last session was too much.
- Judge it over weeks, not days. Load going up while pain drops or holds steady is the program working. Load going up while pain climbs is not.
- Tendons are the clearest case against resting it out. Twenty days of bed rest cut tendon stiffness by about a third in human studies, and ninety days cut it by more than half. Loading every third day during that ninety days held the loss to 37 percent instead of 58.
Push Through It
Every service teaches the same reflex. Pain is information you override. You finish the ruck, you finish the season, you do not go to sick call for something that will probably resolve, and you certainly do not end up on profile over it.
The reflex exists for a reason. But it produces two failures, and only one gets talked about. The first is obvious: the person who trains straight through something that needed attention and turns a manageable problem into a lasting one. The second gets less attention and is far more common after service. Someone felt a thing hurt, decided that meant damage, and stopped. Months later they are weaker, stiffer and in more pain than when they started. Nobody wrote that one up as an injury.
What the Evidence Says
Researchers have been asking a narrow version of this for years: if you exercise with musculoskeletal pain, should the exercise be allowed to hurt? A 2017 systematic review found a small advantage for programs that permitted pain, but only in the short term, with no clear winner at medium or long range. The updated review, published in JOSPT in August 2025 and covering trials through May 2024, landed somewhere more useful: the difference between painful and pain-free programs is unclear, and pain during exercise does not need to be avoided for symptoms and function to improve.
That is not permission to hammer yourself. It says pain during exercise is not by itself evidence of harm. It removes the fear that any discomfort means stop. It does not make more pain better.
The 24-Hour Rule
The most useful test is not what you feel during the set. It is what you feel the next morning.
If pain and morning stiffness are the same as before, or better, the tissue handled what you asked of it and you can do that again. If pain is up, the last session was above what it could take, and the correction is to reduce the load rather than quit the exercise. The guideline adds a third check that is easy to overlook: if it is costing you sleep, the load is too high whatever the pain score said.
This matters because during a session almost everyone misreads the signal. Adrenaline, momentum and the person next to you all argue for continuing. The next morning has no such interest.
Judge It Over Weeks
One session tells you little. A month tells you almost everything, in three patterns.
Load going up while pain drops toward nothing is the ideal. Load going up while pain stays low and steady is acceptable, and describes most people managing something long-standing. Load going up while pain also climbs means the program is wrong, and that is the point to change it or get it looked at.
A 2025 trial in Gulf War veterans is a good picture of the acceptable version. Sixteen weeks of whole-body resistance work, tailored and progressed deliberately slowly to avoid flares. Strength improved, and nobody had to be pain-free to get there.
Tendons Punish Rest
The most common version of this in our community is a tendon. Achilles, patellar, shoulder. Rucking, running and load carriage produce them at rates the civilian population does not match, and the old advice was to rest until it settled.
That advice was wrong, and tendons are the tissue where it is most clearly wrong. A tendon maintains its structure by being loaded. Remove the load and the stimulus disappears, and the tissue starts giving back capacity almost immediately. In human studies, twenty days of bed rest cut tendon stiffness by roughly a third. Ninety days cut it by more than half.
The same research points at the fix. In that ninety-day study, participants who did resistance work every third day finished with a 37 percent loss instead of 58. Not nothing, but a fraction of the damage, from an amount of loading that is well short of training.
One more thing to unlearn. For years the prescription was eccentric work, the slow lowering phase, and nothing else. The 2024 guideline no longer treats eccentric-only loading as superior: isometric holds early, concentric and eccentric together through the middle, faster loading at the end. If you were handed a sheet of heel drops years ago and it did not work, the prescription has moved on.
When This Does Not Apply
All of this is about familiar training aches and long-standing complaints, not a new injury.
Sudden sharp pain, swelling, a joint that gives way, numbness, or being unable to put weight on something are not load-management problems. They are reasons to be evaluated, and the rule for those is the opposite of the one above. Do not wait until morning.
Resource
VA Pain Management, Opioid Safety, and PDMP (va.gov/PAINMANAGEMENT/Veteran_Public). The VA’s own hub for managing pain, built around approaches that are not medication: physical therapy, movement, and complementary treatments. It is the closest thing to an official answer to the question this article asks, it is written for Veterans and the public rather than clinicians, and it carries the VA’s own guidance on when to escalate to care. Free and open, no sign-in.
