Pulled muscle: What does that mean?

Whether is a hamstring, calf or low back, most people have suffered from a "pulled muscle."  But what exactly does that mean?  The medical term muscle "strain" is more commonly used among practitioners, but it is still vague and highly variable.

It would be so much easier to figure out what happened to a muscle if we could just cut someone open and have a look.  But it is kind of frowned upon.  Though there are some techniques such as diagnostic ultrasound and magnetic resonance imaging (MRI) that can aid in the diagnosis of a muscle strain, they can be costly and wait times are often lengthy.  Without imaging, clinicians and practitioners can go by clinical signs and symptoms as well as relying on clinical experience.

Crudely put, a strained (pulled) muscle is a muscle that has undergone some damage.  There are a hand full of grading systems including a more recent "structural" or "functional" grading system, but here is a simplified grading system (it is actually quite old) that can help visualize what is going:

Grade 1 (Minimal): Tear of a few muscle fibers with no fascial damage

Grade 2 (Mild):  Tear of a moderate number of muscle fibers with no fascial damage

Grade 3 (Moderate): Tear of many muscle fibers with partial tear of fascia

Grade 3 Tear including fascia near musculotendinous junction

Grade 4: (Severe):  Complete tear of muscle and fascia

With that being said, a muscle can be strained (or tear) in a number of different spots.  The most common spot for a muscle to tear is the musculotendinous junction (where the muscle meets the tendon).  It is considered the "weak link" in the chain.  It can also be torn in the muscle belly (middle of the muscle) or even at the attachment of the tendon to the bone (called the enthesis).

As you can imagine, it is difficult to come up with a diagnosis (exactly where the muscle is torn) which makes it difficult to come up with a prognosis (length of time for recovery).  For example, a grade 1 muscle strain at the muscle belly may warrant a prognosis of day to day (about a week for recovery with treatment) whereas a grade 1 muscle strain at the musculotendinous junction may require 1-3 weeks of rest and treatment before returning to activity. 

The important thing with muscle injuries is correctly assessing the problem so you can come up with the correct treatment protocol and provide an accurate prognosis for recovery.

Pulled pork is essentially Grade 4 muscle strain!