I thought it really useful to share some information on what actually happens when you have a soft tissue injury, what to look out for and to understand if the pain you feel is a strain or a tear (actually the same thing, just different words)?
To explain lets firstly look at what makes up a muscle?Approximately 85% of muscle tissue is made up of muscle fibres and these fibres are organized in bundles, called fascicles, which are enclosed in fascia (connective tissue) and together this forms the endomysium. The fascicles are bundled together by their fascia and this is called the perimysium, which also carries the blood supply and nerves into the muscle fibres. The perimysium is then enclosed by another rougher fascia, the epimysium. All 3 are joined together and wrapped in more connective tissue, the fascia, and all this creates a single muscle. The muscle fibres are mostly made up of collagen and they provide the muscle with it’s elasticity and transmit the force of the muscle.
The protective covering of fascia also binds the tendons and where the muscle and tendon merge is called the called the musculotendinous junction (there is one at either end of the muscle).
Muscles are made up of groups of muscle fibres and our bodies are organised this way so we can control our efforts. For simple easy tasks we only require a few muscle groups to contract, whereas for harder, maximum efforts we obviously require every group of fibres to be working to their best ability. This is known as muscle recruitment and is achieved by the nerves that supply the muscle and from messages from the brain and our reflexes.
If a muscle cannot respond adequately to meet the demands of a task, it can become overloaded and tear under strain.
A tear or strain (same meaning) can occur for a few reasons:- the muscle contraction required to perform the movement may be more than the muscle can generate.
- there was not enough time to fully recruit the muscle fibres.
- restrictions in the muscle itself (mobility, strength) prevent the full contraction.
- also muscles contract in two ways – they either shorten and so contract concentrically or a decelerating contraction is where the muscle slowly lengthens generally to slow-down and counteract a contractile force/or gravity and this is more frequently when a strain may occur.
Typically muscle injuries occur in one of three places:▪ Within the muscle belly itself (the meaty section of the muscle)
▪ Where the tendon attaches to the bone
▪ At the junction between the muscle and tendon, the musculotendinous junction and this is the most common area of the three.
What does a muscle strain feel like?This happens when muscle fibres are overloaded and fibres start to rupture under the force.
The percentage of muscle fibers involved and the severity of the tear determine the classification of the strain and there are 3 grades used by Medical professionals to diagnose the severity of a strain:
Grade 1 – is a mild strain, only a small numbers of fibres (< 5%) are stretched or torn. While the injury may be painful, strength and mobility are unaffected and recovery is quicker. Grade I is “micro-tear” territory. The fibres have been pushed to the point of starting to tear but not completely. Full recovery is usually 2-3 weeks and you are able to resume activity when you are pain free.
Grade 2 - moderate strain, more fibres involved and torn, it is a much larger injury and the symptoms include pain, swelling and bruising/discoloration. Strength and mobility are significantly reduced and your function is also impacted. Grade 2’s are more severe and take longer, averaging 2-3 months, to fully heal the damage.
Grade 3 – is a complete rupture, a muscle or it’s tendon are completely torn in two. This is a severe injury and includes considerable swelling, bruising and pain you will have complete loss of muscle function with loss in strength and mobility. You may also see defects in the muscle (like gaps, dents, changes to the muscle shape itself) as the swelling subsides. A grade 3 will require medical intervention and often surgery.
Important – the Healing of the strainMuscle strains - going back to “what makes up a muscle” (as noted above) it’s structure, blood and nerve supply and it’s elasticity and contractile properties influence how a muscle repairs. Muscle tissue heals quicker than tendons and ligaments and this due to muscles’ broader 3D blood and nerve supply. Damaged muscle fibres cells divide and then fuse with existing muscle fibres and so importantly, the damaged fibres are able to regenerate and repair.
Tendon strain - tendons connect muscle to bone, they are stronger than muscles, and their fibrous collagen tissues are viscoelastic (they don’t contract like muscles) which means that they allow the tendon to withstand tension and they are able to recoil to normal length after a “normal”stretch.
But, a tendons blood and nerve supply is sparse compared to muscles (and is particularly bad where tendons wrap underneath or around bone e.g. at the ankle, elbow). This means the healing process takes longer, approximately 10 weeks for the maturation stage of healing to be reached. The mostly collagen tissues are not able to regenerate and so a strained area will never regain its original strength and viscoelasticity.
Ligament strain - ligaments connect bone to bone and are formed of densely arranged collagen fibres. They are viscoelastic too (like tendons), so have some elasticity and recoil, but not much as much as tendons, so they tear before they stretch, and again their blood supply is sparse and worse than tendons, and not direct compared to muscle. It is generally understood that ligaments take longer to heal than tendons.
However, because a ligament connects bone to bone it does not need to recoil so it’s healing process is simpler and often ligaments heal close to their original structure but its viscoelasticity will never be the same. The site of injury will always contain scar tissue. This is why injured areas are prone to re-injury.
If you are in any doubt about an injury seek professional advice, preventing injury, or further injury is always better than “soldiering on”.
I hope you found this useful and if you any questions please let me know!