Correcting Faulty Biomechanics* in the Growing Child

Faulty Biomechanics

So often we hear parents bemoaning their child’s posture. “Stand up straight”, “Get your shoulders back”; “stop stooping”; “stand upright” and so on. Parents, quite rightly, blame the advent of television, Playstation, Blackberry’s and the like. “In our day we used to ride our bikes and play outside”. Also accurate, but in today’s world of ever advancing information technology, coupled with increases in traffic and crime, opportunities to allow our children to run amok in safety are few & far between. As we are unable to fight the technological advances, we need to optimise our child’s potential by ensuring correct biomechanics, so that time spent exercising is well utilised.

Sustained postures, such as sitting slouched in front of the computer creates muscle imbalances. Muscle imbalances negatively affect sports performance and create chronic pain syndromes. Perhaps you have noticed your child complain of frequent headaches? Often children & adolescents, as well as their parents, can recognise abnormal postures, but don’t know how to correct them. Vague instructions such as “shoulders back” only damage self-esteem, and in fact, are more harmful than helpful.

We need to be able to teach correct posture in order to improve your child’s:

· Ability to study

· Sports Performance

· Self-Esteem

In this article, we will start by addressing one of the biggest culprits in postural dysfunction; early onset back pain & reduced speed & agility on the sports field- The Hamstrings.

The Hamstrings originate from the Ischial tuberosity (sitting bone) & insert below the knee. Their function is to extend the hip & flex the knee. They are powerful and explosive. They assist us in running fast, lunging to retrieve a ball and return to the ‘T’, ready to explode & retrieve the next ball.

Hamstring Anatomy

What few know is that they attach, via fascial fibres and the robust sacrotuberous ligament, to the sacrum (part of the pelvis). It is thanks to this attachment, that they influence posture and pull on the lumbar spine and the lumbar discs when short.

Always remember the equation: ‘Power = Strength X Range’. Optimal explosive movement requires Power. If you strengthen your hamstrings by, for example, a weight-training program, but you don’t stretch your hamstrings, they will shorten and you will LOSE POWER, negatively affecting your speed and agility. You also increase the risk of Hamstring tears and injuries to the lumbar spine and the intervening discs.

How to tell if your child has short Hamstrings

Optimal hamstring length allows your child to sit comfortably with their legs straight in front of them. They experience no discomfort and do not need to rest their hands behind them or pull on their knees. Their lower back has a normal ‘lordotic’ or C-shaped curve.

Sitting position with optimal hamstring length and ‘C-shaped’ lower back curve

Tight hamstrings force the lumbar spine (low back) into a Kyphosis or ‘D-shape’. This loads the spine every time they lunge.

This is extremely common and may be aggravated by poor or minimal stretching before and after school sport, as well as sitting cross-legged on the class-room floor for lessons.

Sitting position with tight hamstrings and ‘D-shaped’ lower back curve

With the hip flexed to 90degrees , optimal hamstring length dictates that the knee should extend (straighten) fully. The young sportsman in this photo has extremely shortened hamstrings.

We often see one hamstring tighter than the other. This can create torsion at the pelvis, causing low back and sacro-iliac pain. It may present as a difference in leg length.

Shortened hamstrings

From a postural perspective, the tight hamstring forces the pelvis to tilt down (posteriorly). The gluteus muscles atrophy (or waste) and the buttocks become flabby & wasted. The tummy bulges and the thoracic spine (mid back) becomes more rounded. The scapulae, or shoulder blades, then protrude, or “wing’ out from the chest wall.

From a sports perspective, this slows the young athlete down by shortening his stride length. This is frustrating for the young sportsman as he cannot understand why he is slowing down. As frustration grows, he tries to run faster, but his compensatory strategies result in hamstring tears and back pain, enforcing time away from his or her sport.

Before postural correction

Before postural correction

After postural correction and rehabilitation, 12 weeks

After postural correction and rehabilitation, 12 weeks

How to correct tight Hamstrings

Now that we know how to identify the problem, we can start to correct it. Often people report that they don’t bother to stretch their hamstrings as they were born tight , and nothing they do makes any difference. Firstly, we are genetically born with varying types of Collagen that predisposes us to more generalised laxity or stiffness. Nonetheless, with the correct stretching techniques, and correct frequency and intensity of stretch, we can all achieve flexibility that is within a normal range.

Stretch correctly: Ensure that your foot points to the ceiling and that you have an ‘anterior pelvic tilt’ or ‘Headlights up’ position to stretch the origin of the hamstring away from the insertion. This position prevents a compensatory hyperflexion of the midback which overloads the spine, and of course, results in an ineffective hamstring stretch. Placing your leg on a high chair or fence is OK if you are really flexible, but not necessary.

Hamstring stretching technique

Stretch the groin (adductor) muscles.

The Adductors share the same nerve supply as one of the three hamstrings , and some believe that Adductor Magnus & one of the medial Hamstrings are the same muscle. Stretching your adductors quickly helps improve flexibility of your hamstrings.

Groin muscle stretching technique

Stretch Piriformis muscle.

The ‘90/90’ stretch achieves this. As the Sciatic Nerve runs through Piriformis before entering the Hamstrings, stretching of Piriformis improves nerve mobility, and therefore Hamstring flexibility in most cases.

Piriformis muscle stretching technique

Using the Groovi-Grippa ( to stretch the Hamstrings in lying

Hamstring - lying stretch

Practice long-sitting to improve hamstring length when watching television

Hamstring - sitting stretch

How often and how hard should I stretch?

Studies vary on frequency of stretching.

· Best recommendation is to hold each stretch 30-40 seconds. Repeat 3 times and try and repeat that 4 times per day.

· Stretch 6 days per week to improve flexibility. Once flexibility is where you want it, maintain this by stretching 3 times per week.

· Stretch into discomfort and not pain. Tease out the tightness. No jerkiness or bouncing into the stretch as this can cause a reflex tightening of the muscle.

Other Tips

· Stretching should not be a drag, and should not take up too much time. Put some Red Dots on your school bag, Cricket bat, Squash Racket, fridge, kettle, and anywhere else that you spend a lot of time. Whenever you see a Red Dot it should remind you to perform a stretch. E.g., when waiting in assembly or for the kettle to boil.

· Limit your ‘couch potato’ time. Ensure that you get out and enjoy some outdoor activity for at least 30 minutes each day.

Correcting tight Hamstrings will quickly result in an improvement in your posture. On the sports field your mobility and stride length will improve rapidly and you’ll be wondering whether to share your new found secret to success or not!

* Biomechanics is the science concerned with the internal and external forces acting on the human body and the effects produced by these forces.

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  1. By The Cave/CrossFit Marin Main Blog on January 22, 2013 at 2:22 pm

    […] This article from Positive Sport Parent is a pretty good primer on the need to make sure your kids stretch their hamstrings. […]

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