There seems to be much confusion about the differences between a strain and a sprain. Both have to do with soft tissues, which makes it easy to see how they can sometimes get mixed up. Properly identifying what (and how severe) the injury is will ultimately set yourself up for success when rehabilitating that injury. While improperly doing so can be detrimental to both your short- and long-term health.

 

Strain ∨ Sprain:

A strain refers to the: overuse, overexertion, or overstretching of the muscle-tendon unit. Simply put this means that strains are caused by a sudden overstretching of the muscle, or by an extreme contraction of the muscle against resistance.

A sprain refers to severe: stress, stretching, or tearing of a ligament. These conditions are generally met when a trauma-related sudden twist / wrenching motion goes beyond a joints normal range.

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Seems straight-forward, right..? Why then are they mixed up so often? This is really dependent on who is writing / giving the descriptions of each. Each person will have variations as to what is actually affected. Because of this inconsistency, people who have no real experience or knowledge of health care or how the body works (see: most of the internet) will just regurgitate the misinformation – which in turn creates this unpleasant cycle of misinformation.

I will often see older studies and textbooks refer to a tendon related injury as a sprain or strain interchangeably. Newer texts will occasionally do this as well, but most will acknowledge in the end that it should be referred to as a strain-injury. This is because sprains are overwhelmingly used by health care professionals to describe ligament-related injuries. Still.. there will be individuals who say a sprain can also be used to describe any soft tissue, including joint capsules.

Please don’t let the above confuse you; just stick to the simplified: strains are injuries regarding muscles, while sprains refer to ligament injuries.

Both injuries follow the same type of grading system:

Grade 0 (normal)

Grade 1 (first-degree; mild injury)

Grade 2 (second-degree; moderate injury)

Grade 3 (third-degree; severe injury)

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The rest of this post will have two main categories:

1. strains – going a little bit more into what they mean, and also explaining the grades of them

2. sprains – going a little bit more into how they are caused, but focusing on explaining the grades of them

If you would like to find out about the most common areas and types of strains or sprains that occur, you will be able to find a short summary at the bottom of this post. Alternatively you can visit here for a more comprehensive breakdown.

 

Strains:

First, what is a muscle-tendon (aka musculotendinous) unit? This simply means anything to do with a muscle, but it can be explained as more of an umbrella term for the: muscle belly, tendons, where the previous two things meet and blend together (the musculotendinous junction), and each tendons osseous / calcified attachments [onto bone]. This is all to say that you should change how you think of what a muscle is, where a muscle should be thought of as that entire muscle-tendon unit.

A strain can occur quite quickly, as described earlier, but it can also occur in a more drawn-out fashion. By this I mean that the overstretching and overexertion can actually be quite minor forms, but happening time and time again over time. This adds excess stress to the musculotendinous unit to the point that injury is not just potential, but is instead probable.

Contributing Factors:

— inadequate warm up before activity

— less than ideal / limited / poor flexibility

— repetitive overuse or overstressing of that muscle-tendon unit

— strength imbalance between the muscle and its antagonist(s)

— postural malalignments or poor biomechanics that put stress on that muscle

— previous strain to that muscle-tendon unit

 

Image found via Google Image Search, but pulled from https://www.wolvesfitness.co.uk/

G1 (first-degree) Strain:

— minor stretching or micro-tearing to the muscle-tendon unit

— minimal loss of strength

— able to continue activity with mild discomfort

G2 (second-degree) Strain:

— tearing of musculotendinous unit occurs. Degree of tearing can vary from a few to quite a lot

— snapping sound or sensation may be noticeable at time of injury

— palpable gap may appear at point of injury

— difficulty continuing with activity due to muscle weakness and significant pain

G3 (third-degree) Strain:

— complete rupture of the muscle-tendon unit; or avulsion fracture (where a portion / chip of bone at the tendons attachment site is torn off while the muscle-tendon unit stays intact)

— snapping sound or sensation at time of rupture

— palpable AND visible gap at point of injury

— often the muscle will shorten and bundle up (all the tension was just let off, so it will snap back like an elastic breaking)

— cannot continue activity because of significant pain and muscle weakness (or just complete inability to use the muscle as it cannot function)

Muscle and tendons that have a third-degree strain may be surgically repaired, but it is important to do the surgery as quickly as possible. The longer that a rupture or avulsion fracture is left apart then the more tissue fibrosis (oversimplified: hardening) will occur. This makes successful surgical repair difficult.

 

Sprains:

Before continuing on it should also be noted that strains are more likely to accompany a sprain, as a sprain happens at a very deep level of tissue. This means that the surface levels of stabilization (your broader soft tissues) generally have to be affected in order to allow a spraining type of instability to cascade deeper into the connective tissues and joints. This depends greatly on the area in question though.

Contributing Factors:

— joint hypermobility

— connective tissue pathology (i.e. rheumatoid arthritis)

— postural malalignments or poor biomechanics that put stress on that muscle

— history of sprain(s) within that joint

 

Image found via Google Image Search, but pulled from http://atleta.com.au/

G1 (first-degree) Sprain:

— minor stretching or micro-tearing to the ligament

— no instability on passive joint testing

— able to continue activity with some discomfort

G2 (second-degree) Sprain:

— tearing of ligament fibres occurs. Degree of tearing can vary from a few to quite a lot

— snapping sound or sensation may be noticeable at time of injury, while the joint gives way

— joint is hypermobile but still stable on passive joint testing

— difficulty continuing with activity due to pain

G3 (third-degree) Sprain:

— complete rupture of the ligament; or avulsion fracture (where a portion / chip of bone at the ligaments attachment site is torn off while the ligament itself stays intact)

— snapping sound at time of rupture, and the joint will give out

— palpable AND visible gap at point of injury (aka sulcus sign; more common in shoulder joint instability and sprains)

— significant instability with no end point on passive joint testing

— cannot continue activity because of pain and instability

Pain with regards to sprains is usually only applicable to an immediate / acute injury. If it is left to become a long standing / chronic condition then pain will likely no longer be presen,  even though the joint is still hypermobile in the specific direction of said injured ligament.

 

Most Common Injuries:

In regards to strains and sprains there are actually quite a few common areas where these may occur.

The most common sites of injury with regards to strains happen in the: lower limbs – think specific muscles within hamstrings, as well as the gastrocnemius (bluky part of calf) muscle itself; neck; and, rotator cuff muscles.

The most common sites of injury with regards to sprains happen at the: ankle, knee, wrist, and shoulder. With regards to children under the age of 5-6: you can also add the elbow to that list.

For further exploration of each italicized area, continue to this page.

 

I claim no ownership over the main image of an injured soccer player used on this post. The website that I found it on was: http://www.bonsecoursinmotion.com/