A trigger point in a muscle is roughly the equivalent of a stress fracture in a bone. Here's the first of two reports on trigger points, explaining what they are, how they happen, and what to do about them
Have you ever dreamed, while nursing an injury, of finding a magic trigger to facilitate your healing? Or, if you're working hard to avoid injury, wished for a button that you could press to give yourself the maximum chance of not getting hurt?
It is a well-kept secret that there is indeed such a button. I'm talking, of course, about trigger points. Many therapists, trainers, 'strappers' and coaches have at their fingertips (literally!) the opportunity to use their hands to help the athletes in their care to minimise injury, recover from injury, or at least to have something by which they can judge whether their therapist or doctor is worth their salt. Athletes can also use some self-treatment techniques - although, naturally, if they actually have an injury, they should always seek help from a sports-medicine specialist.
This article is the first of two written specially for Sports Injury Bulletin to impart the secrets of trigger points. This first article will discuss the exact nature of trigger points for the athlete, the relevance of muscular trigger points, and the causes of trigger points. The second article, which will appear in the next issue, will get down to the nitty-gritty of how to treat trigger points (both self-treatment and for the therapist) and how to prevent them occurring in the first place.
The articles are written to inform a broad spectrum of athletes, coaches, therapists, and doctors, hence the necessity to use language which is fairly free from medical jargon and complex terminology. Please note that the reference list for both articles is included at the end of the first one.
It is strongly held by many sports physiotherapists and other clinicians associated with sports at the highest level that the vast majority of sports injuries must have trigger point therapy (or a near equivalent that achieves the same outcome) as part of the treatment regime (5, 8, 15, 16, 25, 30). Otherwise, everything that can be done for the athlete is not being done. If you're the athlete in question, never be backward in asking if a therapist is familiar with trigger point therapy in their treatment - sometimes the time off for injury can be lessened by weeks if the therapist is experienced in the techniques that will be outlined later (15, 16). This view is borne out by an extensive body of medical literature.
It is also clearly evidenced in practice. A case report (16) describing the clinical treatment and outcome of three athletes with shoulder 'impingement syndrome' (shoulder pain with overhead activity) shows that all three had had conservative management including activity modification, cryotherapy (ice), pain medication, sub-acromial cortico-steroid injections and basic physiotherapy. Yet the athletes couldn't shake off their injuries. Two of the three were even referred for arthroscopic surgery. When all three were treated with subscapularis muscle trigger point [therapy] dry needling and therapeutic stretching, they responded well to treatment and retained their painless function at follow-up two years later.
With injuries such as this, there can often be various pain presentations, ranging from sharp pain to aching in the lateral shoulder area, vague arm pains, to pain in the inside of the shoulder joint. It may simply be that you are suffering weakness in the arm, poor technique without knowing why, or rapid tiring half way through your normal routine. There is a very high likelihood that your biomechanics have been altered (2, 4, 5, 8) and thus began a chain reaction beginning with the creation of a trigger point in one of muscles in or around your shoulder.
How did the injury begin?
As with the chicken and egg dilemma, it is hard to say whether a change in technique caused the trigger point or vice versa. Suffice it to say that you are cruising toward an injury of greater proportions unless you get it dealt with (ie have the trigger point treated and reassess your technique and biomechanics).
While the most frustrating things about overuse injuries like this is the lack of clear understanding as to how the injury began in the first place, you or the therapist must begin thinking about what factors have caused an overload of muscle or fascial tissue (20). That's where it begins, and as treatment progresses, that's also where it must end. The clinician must try and answer the question, 'Which trigger point began the snowball effect that has resulted in the pain and weakness that you are now suffering?'.
Let me say again: a vast number of sports injuries of all kinds will have at their genesis the development of a trigger point in the muscle or fascia. This trigger point is very commonly the first sign of overload, and from there the cause and effect begins to domino - one tissue breaks down, leading to another being overloaded, which then breaks down, and so on. The whole process is one of trigger points leading to inflammation, leading to pain, then weakness, subsequently joint and nerve dysfunction and finally structural breakdown of tissues and a severe sports injury that can keep you out of the pool or off the track for weeks, months, or years. Of course, just how long simply depends on how long you try and ignore it and fight on, without getting treatment right back to the initial trigger point.
'Often athletes, because of their better overall body sense, become aware of trigger points before they are active enough to cause actual pain'
Hence trigger points develop-ing in your muscle must be taken seriously - a trigger point is the first warning sign that things are not well in your biomechanical system. Learning to listen to your body's alarm bells is a critical skill that can save much time off for injury. Often athletes, because of their better overall body sense, become aware of trigger points before they are active enough to cause actual pain (32) , and the only complaint is 'tightness' or the joint or muscle doesn't 'feel right' (20). These are often warning signs of trigger points and impending injury.
Arguably, all sports people will develop trigger points at some stage in their sporting career. The trigger points that our muscles develop will hamper our performance and simply slow us down for a while, or they will blow out to cause a severe injury. They are a normal part of training and competing because our bodies are biomechanically imperfect and our environments more random than we would like them to be. In a perfect world our bodies would not break down when overloaded - and the football pitch would be just soft enough to prevent stress fractures, yet hard enough to prevent ligament tears when we run over a pothole in the grass. But it just ain't so!
So what exactly is a trigger point?
To all intents and purposes, it is simply a thick knot in the muscle - a way that it reacts to being overloaded. Of course muscles can tear, or tendinitis can develop in a tendon, but mostly they develop a trigger point - in some ways a trigger point is the equivalent of a stress fracture in a bone.
More specifically, a trigger point is a palpable, tender, nodal point of muscle or fascia. It may, however, also be found in skin where scar tissue is present, in old ligament injuries or occasionally in periosteum (the lining of bone). Under a microscope, trigger points appear darker, straightened out and thicker, ranging in diameter from 1-4mm. If located in muscle they cause it to form taut bands or become 'ropey', due to sarcomere disruption and the breakdown of the 'Z lines' (30). A focal area of inflammation develops fairly early on and a collagen matrix forms. Scar tissue has been laid down to bridge the weak link, and can become quite thickened and tough, depending on how long it has been present (3, 7, 8, 19,20, 23, 28). The muscle in which a trigger point is found will usually be weakened and shortened - a trigger point can cause this or result from it. The part of the muscle, or the whole muscle, containing the trigger point is commonly in a state of involuntary tension, or an increase in 'tone'. At worst, muscle spasm will present around a very nasty and inflamed trigger point; muscle cramping can result (21).
'If you find yourself involuntarily twitching from the pain of pressing on a sensitive spot in your muscle, you have just 'triggered' yourself'
Picture a rubber band with a small section that has lost its elasticity, and instead become hardened and rather brittle - that is a trigger point. The muscle is tighter, stiffer, will often be weaker and yet very tense at the same time. A trigger point will be sore when you push on it, and you may likely feel a thick band that you can flick over with your fingers. If you find yourself involuntarily twitching from the pain of pressing on a sensitive spot in your muscle, you have just 'triggered' yourself via the 'local twitch response' (3, 12, 30,32). This will be explained in greater detail in the next article under assessment of trigger points.
Trigger points tend to be restricted to a regional area, as opposed to 'tender points', which are more likely to be widespread and therefore involved in conditions such as fibromyalgia (3). Tender points do not refer pain or have taut bands. There has been some speculation in medical literature regarding the exact nature of the pain related to trigger points, with at least one author arguing that it is possible that the pain is primarily referred from peripheral nerves (22). This would shed new light on the sometimes unusual pattern of pain referral they can give. Most research shows a fairly high correlation between trigger points and acupuncture points - one report sets it at 71% (29).
Alive or sleeping trigger point?
The trigger point presents as either active (Atrigger point)/'alive' or latent (Ltrigger point)/ 'sleeping', depending on whether it refers pain or not (3, 11, 30, 32). This means that when you push on some trigger points and try to elicit the local twitch response, it will begin to cause pain somewhere else in your body on a consistent basis. These are called 'active trigger points' (Atrigger points). The ones that are only painful in the area around the trigger point are called 'latent' (Ltrigger points). All trigger points will be relatively tender on palpation, but patients may be unaware of its presence if it is a Ltrigger point.
The more intense the pain when pressing on the trigger point, and the more obvious the local twitch response, the greater the likelihood of referral pain being present (12). An Atrigger point will in various situations set up what are called 'satellite trigger points',which means that another trigger point has developed in the area that it refers pain to. As an example, in the above case study on the shoulder, trigger points in the subscapularis muscle could set up satellite trigger points in the muscles around the elbow and the athlete could find that his elbow was starting to give him 'niggles' as well.
A 32-year-old marathon runner presented with a 'snapping hip' and knee pain (case study in 25). Previous orthopaedic examination was negative for knee and hip pathology. Myofascial trigger points were located in the ipsilateral (same side leg) tensor fascia lata and gluteus medius/minmus muscles, which when firmly palpated reproduced athlete's pains. These were examples of Atrigger points, in that they produced a referring pain when pressed and 'flicked'. The patient was pain-free after six treatments of manual trigger point therapy and home stretching exercises.
Have I got a trigger point?
Apart from finding a sore spot, you'll know you most likely have a trigger point in one of three ways:
PAIN: Usually you will start to hurt somewhere (2, 4, 20, 26). You may experience stiffness in a muscle or joint that has been overloaded, right through to sharp pains as inflammation signals that there has been tissue damage. Pain may appear at quite a distance from the trigger point (referred pain) (22, 30, 32); it may surface as a significant injury such as Achilles tendinitis or shoulder impingement (14, 16, 21) or it will simply hurt like hell in the muscle or joint that has been overloaded. Sometimes the first thing that starts to hurt is a joint associated with a certain muscle - for example, patellofemoral joint pain in the knee (see also the first article in this issue) may be the first sign of trigger points in the vastus lateralis and/or vastus medialis (parts of the quadriceps) muscles.
MOTOR PATTERN CHANGE: On the other hand, the first time you may know about a trigger point is that things just don't feel 'right'; what was once a smooth action that had power behind it is now relatively clumsy and uncoordinated (8, 14, 24). Your lap times are down, and your coach has noticed it too. What has happened is that somewhere along the line your biomechanics have changed.
The firing pattern of your muscles has been altered (32) because muscles with trigger points may have a lower firing threshold (ie, overactive; find it hard to relax due to an increase in tone) or they may have a higher threshold (ie, sluggish and late) due to the pain associated with contracting the muscle. How much pain in the muscle is involved? That may give you a clue as to whether or not it is weak because of pain.
WEAKNESS: A muscle with one or more trigger points will lose its strength until the trigger point is treated (8, 14, 20, 24). This is either because its nerve supply is compromised by the trigger point (14), or because the trigger point is causing a pain inhibition (that is, it hurts to contract the muscle or move a joint associated with it). If a joint is not being sufficiently protected from excessive shear forces by a muscle that is too weak, it will send pain messages, become inflamed, and soon start to undergo degenerative changes. In this scenario it is definitely not enough to just get into the gym and work 'through the pain'. Often the pain will get worse unless the trigger point is being treated at the same time and joint stability and relearning exercises are prescribed.
What are the factors causing trigger points, and how can we try to prevent them?
There are so many factors that can cause trigger points (2, 4, 8, 19, 23, 20, 24) that it can be like dodging a minefield to make it through to success. The potential for injury is ever-present, and constantly threatening to trip up the progress of the careless athlete. The key is to not overload your delicate biomechanical system while still maintaining forward momentum in terms of speed, strength, and other factors. And mostly we learn by mistakes, by listening to others, and by doggedly not giving up when all the wheels seems to be falling off.
Broadly speaking, we can divide the list of causative factors of trigger points into overuse (these are the ones we can most successfully work to avoid by using our brains and being careful), both intrinsic and extrinsic factors, and non-overuse (factors often out of our control, random events).
(i) Overuse - extrinsic factors
(a) Training errors - excessive volume or intensity, rapid increase or sudden change, excessive fatigue, inadequate recovery - are the factors over which you and your coach have most control. Elite athletes in particular must carefully manage their bodies to prevent microscopic breakdown and consequent trigger points.
(b) Inadequate preparation - pre-conditioning, warm-up to stimulate blood-flow, correct stretch procedure (ie, very appropriate and specific to your sport requirements), brain-stimulating movement drills.
(c) Inadequate massage for sore and tired muscles - the benefits of regular massage have been thoroughly proven, proclaimed and utilised by successful athletes. One per week is all you need.
(d) Surfaces - too hard, too soft: the problem has become a science in itself! The camber of a running track needs to promote balanced muscle development. Moving from outdoor track to indoor may also have an impact.
(e) Shoes/equipment - inappropriate or worn out, it's all the same; they won't be able to support your system. Be careful with new shoes or racquets, or a rain-soaked football.
(f) Environmental conditions - too hot or humid, or too cold, thus compromising blood and water flow to muscles, thereby affecting their temperature and the flow of minerals required for muscle/nerve function.
(ii) Overuse: intrinsic factors
(a) Poor biomechanics - much can be said here. There is no ideal biomechanical system to aim for, rather principles to follow that allow muscles to approximately remain balanced either side of a joint. Even if you have flat feet or poor posture in your spine, the real issue is whether or not your muscles can support that joint. Some of the best sprinters in the world have flat feet, but those feet are extremely well supported to give their muscles a good biomechanical advantage. Having said that, poor foot biomechanics will require good orthotics (arch supports) to prevent trigger points developing in the legs or back (24).
Good biomechanics will result in proper muscle balance, and consequently good muscle performance and joint protection. Whenever a muscle or joint is allowed repetitively to move too far beyond its 'neutral zone', trigger points will start developing. Thankfully, the body is very receptive to relearning good movement patterns from poor ones that are at the root of this issue. With concentrated effort you will be surprised how well it will adapt and even find it natural to move in a healthier pattern. Good movement patterns are an important key to maintaining muscle balance and keeping trigger points at bay.
(b) Muscle fatigue - repetitive movement or loading beyond a certain point will fatigue a muscle, and eventually result in breakdown of the muscle within its structure. Hence a trigger point forms. This happens regardless of biomechanical issues. Allow time and other helping factors to give the muscle a good chance of recovery.
(c) Muscle weakness - as for above, except that endurance is not the issue but rather the muscle's capacity to produce sufficient force under loading. When you are performing a movement pattern under load, for example, sprinting from a start, you may not be aware that your gluteus medius isn't strong enough to keep your pelvis in a stable position, so it may be contracting beyond its capacity and developing trigger points within it (see also SIB issue 9, page 8). The first you know about it might be a sore low back or tight, achey hamstrings. Specific strengthening of stability muscles (eg, abdominals, glutes, and scapular and rotator cuff muscles) as well as the more obvious prime mover muscles (eg pecs, lats, quads and hams) is essential.
(d) Joint instability/ hypermobility - if a joint is no longer constrained by non-contractile tissue (eg, an ankle that has had a ligament tear) then muscles supporting that joint will be required to overwork to protect the joint from damage. trigger points will then develop in that muscle (18, 20, 28).
(e) Lack of flexibility in a muscle - generalised muscle tightness will tend to increase the chances of trigger points forming (10, 16, 20), but this again has more to do with muscle imbalance around a particular joint. Tightness in specific muscles that are required to be flexible for the demands of the sport will definitely develop trigger points - for example, rugby goal-kickers with tight hamstrings.
(iii) Non-overuse factors
(a) Trauma - acute injuries to muscle may be related to a build up of trigger points (by weakening muscle tissue), but certainly muscle trauma such as a partial or full thickness tear of the calf muscle tissue will inevitably cause widespread trigger points. They will also need treatment in the process of rehabilitating the muscle tear.
(b) Post-operative - trigger points will often form during rehabilitation after surgery, as a strengthening regime is carried out. This is due to weakness resulting in muscle imbalance. In a recent study (6), 10 patients with on-going pain after significant surgery to their knee (and subsequent examinations to rule out any complications from the operation) underwent trigger point treatment and an overall average decrease in pain levels of 75% was noted.
(c) Nutritional and health issues (8, 20, 27) - hypothyroidism, folic acid and iron insufficiency are repeatedly mentioned in trigger point literature as relevant. A host of vitamin and mineral deficiencies may also have an impact (the Bs,Vit C, Ca, K and Mg). It makes sense that unhealthy muscle tissue will have poorer regenerative powers and be more susceptible to breakdown.
(d) Psychological - impaired sleep, excessive stress, and depression can be related via psychosomatic pathways (ie, body-brain connection). However trigger points also have an impact on your autonomic nervous system and can cause emotional distress (20).
To summarise, the muscles hold a critical secret for treating injuries and keeping them at bay - those hard little knots your muscles develop when overloaded: the deadly trigger points. It is not an overstatement to say that the majority of sports injuries have an element of trigger point-related dysfunction and the right treatment must also include trigger point treatment.
The causes of trigger points are many and varied - it usually takes the experience of years in sports medicine to assess what might be causing them, yet common 'body-sense' and awareness will go a very long way. To be trigger point-conscious means to watch your flexibility, watch your preparation, watch your technique, watch your body (literally on video), watch your coach and therapist, your state of mind, and your diet.
Thankfully, trigger points are very treatable, and while most athletes will rarely if ever be totally free of them, they can greatly minimise the impact of trigger points on their bodies with regular 'releasing' routines. (These will be outlined in the next article). In addition, treatment of trigger points can greatly improve performance even when no pain is present by improving strength, flexibility, and biomechanical advantage.
Next time I will look at a host of practical treatment ideas for the therapist and the athlete who are keen to get rid of the dreaded trigger point!
Bibliography/ further reading
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