How to Heal a Back Injury - Acute and Sub-Acute Phases

Stages of Healing

Senior woman being examined by physical therapist.
Vertebral compression fractures can cause sharp back pain. lightwavemedia

Neck and back injury healing goes through stages - each with their own characteristics. Different things are happening at the injury site in each unique phase; this means that your exercise choice and activity level will likely vary depending on how long it's been since you've injured yourself.

The good news is there are only 3 stages you really need to know about when you are healing a first back injury.


How to Heal a Back Injury - The Acute Stage

Also called the inflammatory stage, the acute stage occurs at the time of the injury, and usually continues for up to almost a week. During the acute stage, symptoms of inflammation, which include redness, swelling, pain at rest and loss of function will likely occur.

The inflammation and pain during this first phase is caused by chemicals that are released into the area in response to the damaged tissues.  These chemicals are meant to immobilize the region in order to help it heal.  But they can also cause pain and serve as a part of a feedback mechanism that signals swelling to continue.

Scar tissue also begins to form during the inflammatory stage.

During the acute stage, rest and gentle movement, along with physical therapy and anti-inflammatory drugs are generally recommended.

The Sub-Acute Stage

The sub-acute phase is marked by new growth of connective tissue and capillaries (to help repair damaged structures) and  decreased inflammation.

Scar tissue continues to grow during this time, as well.

In this stage your tissues are still very fragile, so placing stress on the injured area is best limited to a therapist's or doctor's skilled hands.

Most physical therapists recommend that you begin with gentle movement during the sub-acute phase - with the intent of gradually building up to exercise.

 Mild isometric exercise might be appropriate. Because activity is restricted at this point, your muscles may be weak. This can be addressed with specific, low-intensity exercises.

The sub-acute phase follows the acute phase and depending on the type of tissue that was injured (i.e., tendons vs muscles, where tendons have less blood supply and therefore will likely heal more slowly,) usually lasts between 10 and 17 days.


Kisner and Colby Therapeutic Exercise, Foundations and Techniques, 1st ed.

Bryand, Michael, MD. Wound Healing Clinical Symposia, Vol. 29 No. 3 1977, CIBA Pharaceutical Company.

The Chronic Stage

During the chronic stage of healing a back injury, the inflammation goes away entirely.  The new collagen fibers that are laid down to form scar tissue are quite strong, and the wound becomes smaller.  During the chronic stage of healing a back injury, pain associated with the injury tends to be limited to the end reaches of the joint range of motion.

The first 10 weeks of the chronic phase are prime for doing exercises that help remodel the fibers so, as much as possible, they function the way they normally did before you were injured.

(This prime time may also include a bit of the later part of the sub acute phase.)

Why should you care about doing exercises during this special 10 week period?  Because otherwise, you may permanently lose some of your ability to move and function in your daily life.  After about 10 weeks, something in the chemistry of the  scar tissue changes, and the only way at that point to re-acquire the strength and flexibility your joint needs to be healthy and keep you moving along in life is with surgery or by getting manual release treatment from a physical therapist.  But doing exercises during this 10 week period that are prescribed by your therapist allows you to positively influence your back healing - sooner and more thoroughly.

Related: Tips for Sticking with Your Back Exercise Program

During this time the scar tissue can be remodeled by the stresses placed on it by the exercises you do. This means that the activities and exercises the injured part is taken through will affect where scar tissue fibers (and therefore their strength) will be located.

That is why getting exercise instruction from a physical therapist is crucial for healing.  An adjunct treatment that may also help during this phases is massage therapy.

But the chronic stage of healing, which begins after 21 days, doesn't end after that 10 week prime time.  Actually, it may continue for quite some time.

And even after the special 10 weeks has past, continuing with your exercises will continue to make you stronger, more flexible, as well more functional and pain free.


Kisner and Colby Therapeutic Exercise, Foundations and Techniques, 1st ed.

Bryand, Michael, MD. Wound Healing Clinical Symposia, Vol. 29 No. 3 1977, CIBA Pharaceutical Company.

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