Positive Health Online

There are a variety of factors that need to be considered when you exercise to make sure it's performed properly, safely and for maximum benefit. Some of these factors are common knowledge; warm up and cool down, use correct technique, don't over train, use the right equipment, progress your training sensibly and find a good coach are some. Others are less understood, and one that we will be talking about here is Biomechanics.

What is Biomechanics?
In scientific terms, mechanics is the science of matter and forces and their effects on movement and equilibrium. Biomechanics is how this is applied to the body. It is often divided into 2 sections:
Static; which is concerned with the body in balance;
Dynamic; which is concerned with the body in motion.
The human body and how it moves in mechanical terms can be divided into two areas of study: 'extrinsic' and 'intrinsic' biomechanics.

Extrinsic Biomechanics looks at movements and the measurement of those movements, then establishes the most efficient way to perform them. It is an important science that is relevant to any sport, fitness or physical conditioning programme.

Intrinsic Biomechanics, on the other hand, is the study of how the body is able to perform those tasks or movements in relation to the individual's mechanical make-up.

Example
Take sitting at a computer using a computer mouse and keyboard as an example. Have you ever noticed that during the day (or the period of time that you are on the computer) that your shoulders slowly elevate? This 'mousing' and keyboard activity can cause tension in the trapezius muscle and can result in discomfort if you are a regular computer user. Conventional wisdom says you should periodically lower your shoulders, you should have them massaged and you should look at your desk ergonomics.These are extrinsic biomechanical interventions that can help, but unless you understand the cause of the shoulders elevating, any strategies to resolve the problem will be ineffective in the long term, even if they do help in the short term.

One common intrinsic biomechanical cause is tension in the median nerve. This is a nerve that runs from your neck, down your arm into your fingers. When you perform repetitive movements nerves become 'tensioned', in other words they get stiff, and the muscles that would take the tension off the nerve (if they were to contract), then go into spasm to minimize the tension. In this example the trapezius muscle takes the tension off the median nerve by elevating the shoulder. So if the shoulder needs to elevate to take the tension off the nerve and you are being told to press your shoulder down, this can actually increase the tension on the nerve and at best hinder progress, or at worse can cause further problems.

Median Nerve Test

The take home message here is to make sure that the intrinsic biomechanics are dealt with before any extrinsic strategy is adopted. So how does this apply to Functional Training, Sports Performance, Strength and Conditioning, Injury Prevention, Rehabilitation and Injury Management?

Functional Training and Sports Performance
Functional training is the latest trend in fitness at the moment. It works on the premise that the body is designed to work by performing patterns of movement which engages muscles in natural way rather than in one plane of movement. So, for example, a functional pattern would be throwing or squatting which works many groups of muscles, rather than arm curls (where you bend the arm holding a weight), which works one group. But what prepares you for functional training? Think about a squat movement, which involves your ankle, knee and hip. You can have problems with any of those joints (and others) and sometimes the movement will be compromised: sometimes the knee bows inwards, weight goes through more one side than the other, your body bends forwards too far or any number of different mal-alignments. Sometimes though the body compensates for problems with one body part, in fact it is quite adept at doing so, and in these cases you cannot see any abnormality in the movement pattern.

So there is a risk in relying solely on this form of exercise and screening.

Understanding how each of the body's joints or systems works independently is essential to see whether that section has the capacity to function as part of the whole. Remember this phrase; if it isn't functioning it can't be functional. A biomechanical screen will provide this information and is used as a precursor to functional screening and training. Once each joint or system has the capacity to function correctly, functional training using combinations of joints and systems, then becomes more likely and the movements are pure not compensatory.

The take home message here is make sure you have your biomechanics checked out before you decide which type of training you are going to perform; whether it be functional training, sports performance or even bodybuilding.

Biomechanics and Sports Performance
The performance of a sport is affected by many different factors. Your biomechanical function has a profound effect on how your movement patterns are controlled and compensated for during the performance of a movement or series of movements. It is often these compensations for biomechanical issues that lead to faulty movement patterns and ultimately compromised sports performance.

For example, if a golfer had an overactive infraspinatus muscle (one of the rotator cuff muscles) in the shoulder, it could significantly affect their ability to deliver a consistent swing. As the club moves through the swing, building up speed from the top of the backswing towards impact, the capacity of the left infraspinatus to stabilize the left shoulder and contribute towards external rotation of that shoulder is critical when delivering a consistent club position to the back of the ball. Simultaneously although the right infraspinatus is relatively inactive during the downswing (apart from some stability work), it needs to work very hard eccentrically to slow the shoulder down after impact.

It is extremely difficult to establish an overactive infraspinatus muscle using functional screening or indeed medical screening, but it takes 10 seconds in a biomechanical screen and is evidenced as being reliable and accurate. The same principle applies to all arm related events, including javelin throwing and tennis, so the take home message here is get biomechanically screened as you are increasing the risk of injury and compromised performance without one.

Biomechanics and Injury Prevention
There are many causes of injury ranging from poor technique, poor 'core' strength, poor preparation, insufficient range of movement in the relevant structures and many others. Your correct biomechanical function is also a critical factor, but is generally less understood. A biomechanical screen will highlight the flaws in your pelvic, shoulder and knee function, as well as check whether you have any low grade muscle spasm in key muscles, which may be restricting both movement and the correct functioning of a joint. In addition a biomechanical screen will check your nervous system and highlight any problems that may cause your body to compensate and break down.

For example, a rotated pelvis is something that many of us have, but are not aware of. One of the results of this is what's known as a functional leg length discrepancy. As the pelvis rotates forwards, the level of the ilium (pelvic bone) on that side can drop lower compared to the opposite side and make that leg appear longer. This can result in a variety of different injuries depending upon how you compensate; it can cause lower back pain, knee pain, shin pain, hamstring injuries, even foot pain. Some people have been known to have upper back and shoulder problems from this too. By screening issues like pelvic rotation, the risk of many of these injuries can be significantly reduced. The solution is to perform tests to see whether the pelvis is working biomechanically correct. Once established there are a variety of corrective exercises that can be performed to re-align the pelvis and encourage it to function correctly again.  

Strength and Conditioning
Strength and Conditioning (S&C) has had something of a renaissance in the fitness industry in recent years following the great work by the UK Strength and Conditioning Association. The scientific principles in S&C are generally evidence based and anyone who prescribes exercises for any reason should learn and apply them.  Clearly biomechanics plays a critical part in this type of training too. Irrespective of the type of training you perform, you need to be biomechanically prepared, otherwise that training can cause injury or at least compromise your performance.

Example
Bench pressing is one of the oldest exercises in strength and power training, yet there is some debate around the technique; in fact in some circles, the actual value of the exercise is being questioned. The question here is; how far down should the bar be taken to the chest and how does an understanding of biomechanics help you recognize the answer? This cannot be answered without asking a further question: for what purpose are you bench pressing? The reason the bar has been typically taught to be taken to the chest is because in competitive powerlifting the rules say so. There has to be a standard point that can easily be identified by the judges. So in this context it is correct to take the bar down to the chest. In other circumstances, it may not be.

Outside of the competitive arena, the easiest way to find how far down the bar should go for your shoulders is to take a light broom stick and use it to bench press. As the bar lowers you will rotate more-or-less around the axis in the shoulder joints. This is efficient and minimizes the load on the shoulders. When you get to the natural end of your shoulder ranges of movement, the axis will change from the shoulder joints to the shoulder girdle. When this happens, the type of movement changes from rotation around the shoulder joint to a retraction of the shoulder girdles, in other words they move together and the width of the shoulders actually reduces. This alters the plane of movement and mechanics to the point that at the bottom, when the shoulders are retracted; the return movement means you are pushing out to the side more than you are pushing straight up. Given that the bar is forcing the humerus down and the muscle contraction is working at an inefficient angle to the line of gravity (pushing out to the side), this makes for an awkward position and ineffective movement that can cause impingent.

So, the take home message here is to bench to the depth that your shoulder joint ranges allow, without letting your shoulder blades glide towards each other, unless of course you are a competitive power lifter in which case you'd better hope there are some rule changes!

So if you have biomechanical problems with your shoulders or upper back (thoracic spine), then the loading through your shoulders while bench pressing can be high enough to cause injury; combine this with a poor technique the risk is even higher. Understanding the biomechanics of the movement will help with your technique and reduce the risk of injury during the exercise.

Rehab and Injury Management
Therapists are becoming increasingly skilled at being able to diagnose and treat injury. One factor that is now recognized to compliment that process is the understanding of biomechanics. The kinetic chain and how structures relate to each other in biomechanical terms can have a profound effect on outcomes. Understanding that the shoulder can be a biomechanical cause of pelvic and low back injuries for example (and vice versa) is a major step forwards in the management of injuries. Recognizing how to measure this and make evidence based decisions based upon those outcomes is another. As biomechanics is increasingly used in the treatment of musculo-skeletal injuries, they are getting better quicker and the risk of recurrence is less.

For example, a player with 'non-specific' groin pain which was failed to be diagnosed despite specialist consultation and MRI scanning was treated successfully by working on the biomechanical function of his opposite shoulder. The body is an integrated system and all of its component parts affect each other to some degree. The key here is to ensure that the injury is being treated correctly of course, but running along-side this, a system of biomechanical screening can identify and eradicate any biomechanical causes of that injury to reduce the load on the injured structure.

So if you have an injury that is failing to respond to treatment, chances are there is a biomechanical cause somewhere else in the body that is loading that susceptible area. Finding the biomechanical cause can be critical in getting back to work and sport and importantly minimizing the risk of recurrence.

Of course, no one system or protocol can be the panacea for all ills, and biomechanics is no exception. However, understanding the principles of it, being able to use a screening process that encompasses it and having the knowledge of how to prescribe exercises that improve it, can be an important part of everyone's screening and exercise programme.