Muscle tightness can often be referred to as the force with which a muscle resists being lengthened.
We often experience muscle tightness as pain or increased tension in the muscle belly through movement. For example, you perform a high intensity running session and your calf muscles become ‘’tight’’. Due to this relationship of pain and movement, muscle tightness is often associated with overuse. I feel that this is simply due to misinterpreted information. A better definition of ‘’muscle tightness’’ is a hypertonic muscle that is being repeatedly stimulated.
In other words, your central nervous system is stimulating the muscle to constantly contract. Sub sequentially, this muscle now lacks the ability to relax, which we experience as a resistance to lengthening. It is important to note that muscles directly act on the joint that they cross. If one muscle (the agonist) is hyper stimulated and cannot lengthened, then another muscle acting on the same joint (the antagonist) will be constantly on stretch. As a result, your CNS will reflexively inhibit or ‘’switch off’’ the antagonist muscle as a protective mechanism.
You now have a hypertonic muscle on one side and a hypotonic on the other. This muscle imbalance leads to increase injury as the joint torques across the joint are unbalanced. Joint dysfunction ultimately creates poor movement patterns, early fatigue and poor stabilisation, which are all mechanisms of injury. Before moving on, let’s explain some things about muscle tightness first…
1) Muscle do not become tight from overuse:
Go perform 100 reps of a bicep curl with perfect form. Although your bicep will hurt the next day, once the muscle fibres have repaired, your biceps will not become tight and should return to normal function. The mechanism by which muscles being tight is joint instability. If a joint is structural unstable as a result of injury or poor movement, then the muscles surrounding that joint must compensate and create stability. This increase in active tension creates hyper stimulation of the muscle which athletes experience as tightness. Therefore, muscle tightness is not the cause of injury, but simply the symptom of an underlying movement problem. If you have a tight muscle, it is your body telling you that you are moving poorly.
2) Tightness in one specific muscle is the result of tightness in an entire system:
Athlete would have experienced this many times. When you get a tight calf you foam roll it or get a massage and the tightness disappears. What you have done is switched off the muscle belly and taken away the symptom of pain/tightness. The next training session your calf becomes tight again. This occurs because often the site of pain is not the cause of pain. You experiencing a tight calf is actually the result of other muscles restricting optimal movement and sensory input.
3) Your muscle tightness is the accumulative result of many years of poor movement:
Unless you have sustained an injury or pathology, your muscle tightness did not occur over night. Muscles primarily become tight as a result of the joint that they act on being unstable (unbalanced torques). For example, tightness is the hamstring will most likely be caused by an unstable pelvis (increase anterior pelvic tilt), poor movement pattern (inability to hinge at the hips) and poor motor recruitment (the hamstrings are recruited as prime hip extensors). Having these 3 characteristics in combination with thousands of repetitions will result in the hamstring being placed under increase tension as they are not supported by either the surrounding muscles or a structural base.
4) Muscles tightness progress proximal to distal:
Muscle tightness begins from a young age, usually around ages 14-16 as this is the time when your inborn movement pattern start to deteriorate. Firstly, environmental factors or uncorrected movement patterns create tightness in your hips or torso. For example, repeated sitting and walking with your feet turned out has created a tightened T.F.L and an unstable pelvis during running. Joint instability in your pelvis will eventually lead to a compensatory movement pattern in which the distal joints will also experience joint dysfunction. As a result, the joints of your knees and ankles will also experience muscle tightness, such as in your hamstrings and calf.
How muscle tightness relates to movement:
The first characteristic of a tightened muscle is its effect on muscle length and force output. Tightened or hyper stimulated muscles can be identified as being over shortened which means they have a high resistance to lengthening. These muscle have an altered length-tension relationship. What this means is the muscle cannot reach the optimal length with which a muscle can produce maximal force. Furthermore, the muscle will lose or replace functional contractile tissue with non-contractile tissue as a result of hyper stimulation, often leading to muscle hypertrophy.
Although the individual tightened muscle will still retain nearly all of its contractile strength and may even get stronger, if the muscle cannot lengthen under load, joint torque will be reduced. In relation to movement, it is important to note that the amount of force your body can produce is the sum of all its joint torques. If the joint torques at one joint are unbalanced, this will create a chain reaction of instability to the other joints producing the movement.
Secondly, when a muscle becomes tight it lowers what is called its activation threshold.
The activation threshold refers to how much neural stimulation is needed to cause the muscle to contract. Lowering this threshold means the muscle is readily activated with movement. Because your body will always take the path of least resistance, tight muscles are often recruited first. This is why no amount of cueing can change a movement pattern. Also, the number of motor units stimulating that muscle is reduced, leading to poor muscle synchronisation.
Put simply, your body will initiate a movement with a tight muscle (causing pain or injury) and the movement pattern will be poor and unstable. Go have a look at an athlete with a tightened T.F.L perform a single leg squat. As a result of the tightened muscles being recruited first, other prime movers and stabilising muscles are inhibited. This results in an altered movement pattern. In the example above, the T.F.L has now been recruited as the prime abductor of the hip. As a result, the standing hip will most likely hip hike (adductor), followed by a valgus knee and pronated ankle.
The final and perhaps the most over looked component of muscle tightness is your limbic system.
The limbic system is a complex nervous system in your brain that deals with stress, fatigue and other emotional factors. If you have increased amounts of stress or fatigue commonly experienced from over training, it may result in muscle tightness due to the central nervous system not receiving nor supplying optimal neural information. Muscle tightness can sometimes be simply resolved by taking an extra day off training and sleeping more, especially If you experience a tightening in a muscle after repeated days of training.
As previous stated, muscle tightness is a symptom of poor movement and body position. If you are unsure as to whether or not you have an over stimulated muscle, here are the two common ways athletes will describe or experience muscle tightness. Muscle tightness can either be experienced as trigger points or muscle spasms. Trigger points are localised areas of hyper irritability within the muscle belly.
These areas are not painful during movement but are very sensitive on palpation. Trigger points create ‘’knots’’ within your muscle fibres that restrict blood flow and reduce the muscles ability to lengthen. Muscle spasms on the other hand are a result of joint dysfunction and cause reduced blood flow and altered movement patterns. A muscle spasm produces problems within the CNS, specifically in the interneurons of the spinal cord. This means the information that your muscle receives cannot be sent to the brain. As a result, your spinal cord will produce a reciprocal inhibition response to movement for protection of the muscle. For example, a muscle spasm of your biceps will result in the inhibition of your triceps.
On a final note, muscle tightness or over stimulation of a muscle is a far more common cause of faulty movement than muscle weakness.
If a prime mover is weak, an athlete will still be able to complete a movement due to the body’s ability to compensate and adapt by recruiting other synergist muscles. The problem is that on the outside, the movement pattern can look optimal even though the athletes motor control system is damaged. On the other hand, there is no place to hide with muscle tightness. The athlete will either be unable to perform the movement or will significantly struggle through it, giving the coach a clear indication of a faulty movement pattern.