There is somewhere around 640 skeletal muscles in the human body. Skeletal muscle is a complex network of muscle fibers, connective tissue, nervous tissue, and blood vessels. The connective tissue forms a framework of support by surrounding individual muscle fibers, bundles of muscle fibers (called fascicles), and finally the individual muscles that are made up of these fascicles. Another type of connective tissue, called fascia, plays an integral role in how muscle functions. Deep fascia separates neighboring muscles from one another and allows for these muscles to glide smoothly past one another as they contract. Superficial fascia separates muscle from the overlying skin, and also allows for smooth movement of contracting muscle. Dysfunctional fascia can increase the likelihood of suffering a muscle strain.
Each muscle fiber is composed of many sarcomeres, which are the contractile units of the muscle. When a muscle contracts, tension is created in these sarcomeres and this tension is controlled by the Central Nervous System. Muscle strength is affected by the number of sarcomeres present in a muscle, as well as by neural recruitment of muscle cells. Muscle length is also a byproduct of the number of sarcomeres, with an increased number of sarcomeres in alignment corresponding to increased muscle length. Muscle strength and length imbalances can increase the likelihood of suffering a muscle strain.
Factors That Increase the Likelihood of Suffering a Muscle Strain
A muscle strain is defined as damage to some part of the contractile unit caused by overuse (chronic injury) or overstress (acute injury). Strains can be graded as mild, moderate, or severe. Several factors contributing to muscle strains were mentioned under The Anatomy above. Here is a list of the aforementioned and some additional causes:
- Dysfunctional joints above or below the injured area: if motion is limited in one area, the body will compensate and increase the demand on adjacent structures and tissues
- Dysfunctional fascia: if the fascia does not allow for smooth sliding and gliding between neighboring muscles and other structures, adhesions and scar tissue can develop
- Poor flexibility: this can be due to muscle length or fascial adhesions (scar tissue)
- Overstretching: stretching a muscle beyond its ability to recoil and return to its resting length
- Muscle strength imbalances: strength differences between muscles or muscle groups that are meant to oppose and control one another’s movement
There are other factors that can contribute to or increase the likelihood of a muscle strain, but we will focus on these five as we discuss both the rehabilitation and prevention of muscle strains.
Signs and Symptoms of a Muscle Strain
Common signs and symptoms of a muscle strain include:
- Sometimes an audible ‘POP’ is heard
- Localized pain at the site of the tear
- Pain with stretching of the injured muscle
- Pain with contraction of the injured muscle
If you have suffered a muscle strain, the general R.I.C.E. rules apply:
- Rest: take it easy
- Ice: ice no more than 15-20 minutes with at least an hour between applications
- Compression: use an ACE wrap or compression sleeve; don’t compress too tightly
- Elevation: keep the injured muscle above heart level
There are 3 phases of healing, each with different goals for rehabilitation:
Inflammatory Phase (Acute): This phase can last from 0-5 days, but generally inflammation begins to decrease after 48-72 hours post-injury. Follow these guidelines:
- Range of Motion: perform gentle movements, but not to the point to pain
- Gentle stretching: not to the point of pain
- Decrease physical or recreational activity: to prevent further injury
Subacute Phase: This phase generally lasts between 5-21 days post-injury, but is variable depending on the severity of the injury. During this phase muscle fibers are regenerating and being laid down randomly within the muscle. It is important to gradually resume activity during this phase to help realign the new muscle fibers into an efficient position. Follow these guildelines:
- Stretching, with increased intensity: perform 3 sets of 30 second holds when stretching
- Massage: helps to realign new muscle fibers and free up fascial adhesions
- Gradually resume resistance training: this will also help to realign muscle fibers, as well as increase strength
- See a Physical Therapist: they can help address factors that may have contributed to the strain, such as spine mobility, pelvis mobility, inefficient muscle recruitment patterns, etc…
Maturation Phase (Recovery): This phase can last up to 6 months post-injury for the most severe cases. This phase should consist of the following components:
- Resistance training with increase intensity: increase intensity slow and steady
- Endurance training: emphasize muscle strength and endurance
- Aerobic/Cardiovascular conditioning: don’t forget this!
- Balance and Proprioceptive training: this could be another reason why the strain occurred in the first place
- Agility training: quick movements and plyometrics. This should be towards the end of rehabilitation
For resistance training and aerobic training guidelines, read this article!
Muscle Strain Prevention:
Based upon the predisposing factors and the rehabilitation guidelines we can formulate some key concepts to help prevent muscle strains from occurring. Follow these five guidelines:
- Increase flexibility: Stretching all major muscle groups before and after a workout is a great idea. Hold all stretches for 30 seconds. Don’t stretch to the point of pain. Beginning a Yoga program would be a great idea, but start easy and take it slow.
- Increase soft tissue mobility: This is a fancy way of saying, “get rid of the scar tissue and adhesions in and between your muscles”. Remember the fascia that we’ve talked a little bit about? Sometimes stretching isn’t enough. A good physical therapist or masseuse can help you here!
- Correct strength imbalances: don’t ignore muscle groups. For example, work your quads and your hamstrings, your triceps and your biceps, your low back and your abs, etc… Strength imbalance not only can predispose you to a muscle strain, but possible worse!
- Work concentric and eccentric contractions: A concentric contraction means that the muscle is shortening as it is contracting. An eccentric contraction is the opposite; the muscle lengthens as it contracts. The easiest example to visualize this is a biceps curl. As the weight comes up the biceps is contracting and shortening (concentric contraction). As the weight is relaxed to its resting position, the muscle is still contracting as it is lengthening (eccentric contraction). MOST MUSCLE STRAINS OCCUR DURING ECCENTRIC CONTRACTIONS! You can integrate eccentric training into every exercise. For example, when you squat, squat slowly down to your end position (controlling the eccentric contraction) and then push up. When you bench press, lower the bar slowly (controlling the eccentric contraction) and then push up.
- See a good physical therapist, chiropractor or osteopath: they can make sure that you are moving efficiently, and eliminating extra, unnecessary demands on your muscles.