Postural and Global Muscles

Let’s talk about a new way to look at our body's muscular system. Developing a deeper understanding of how our muscles work and how we can create balance will move you in the right direction for a healthy and pain free life! A system of assessment that we often use in the clinic during postural assessment is to identify which muscles are lengthened and which muscles are shortened. To understand this further, we need to discuss the concept of postural and global muscles. In the 1960s a physiotherapist named Dr. Janda demonstrated variations in muscle balance against the force of gravity. He determined that through a person's walking cycle certain muscle groups were acting as postural muscles while the second group were acting as global muscles. These were identified by the fibres that made up the muscle tissue.


Putting that into practice, when you are standing, sitting and walking your postural muscles are responsible for holding you upright and are mostly made up of slow-twitch fibres, they work against gravity. If they tighten and restrict movement it can be difficult to achieve and maintain correct posture. You need to maintain good strength in postural muscles to support your body in its correct posture. Global muscles are used for dynamic movement and mostly contain fast-twitch fibres, they are the ‘on-off’ muscles, such as biceps and hamstrings.


Postural Muscles = Slow Twitch Fibres = Support Muscles

Global Muscles = Fast Twitch Fibres = Activation Muscles


If we think back to our ancestors, they were constantly changing between various dynamic, static and complex movements. Something we call Activities of Daily Living (ADLs). They efficiently utilised the body's mechanics, both their postural and global muscles. Fast forward a few thousand years and our lifestyles have changed dramatically, we are now more sedentary and we mostly move on a one dimensional plane (Up + down, Push or Pull). Our understanding of the relationship between these muscle groups and how we can improve our use of them can have an impact on our journey to pain free movement.


It is natural as we age for the body's systems to weaken, the old saying “use it or lose it” comes up a lot in our blogs and it is very true here. If we aren’t using our postural muscles to support us, because we are sitting (and often slouching) for long periods of time these postural muscles don’t activate. If we’ve let our postural muscles waste, our global muscles will compensate. This will cause them to overwork. We want our bodies to work most efficiently, which means each group of muscles doing the work they were designed for and holding up their end so to speak.


Let’s look at an everyday case study;

A client who experiences lower back pain when walking. After an assessment on his posture and gait cycle, it was identified that there was restriction in his postural muscles (obliques, transverse abdominis) and a shortening of the global muscles (hip flexors and calves) causing a shuffling gait, limited hip extension and a poor propulsion pattern (pushing off toes).


Our treatment plan recommendation for a client presenting with this situation would be to lengthen shortened hip flexors and calf muscles through soft tissue bodywork and provide homecare exercises to strengthen global muscles and open up the postural muscles over the course of 3 - 5 treatment sessions, depending on severity. The end result would be an improvement in the gait cycle and significantly reduced pain. With continuing at home care and maintenance treatment we expect the pain to be eliminated and function sustained over time.


With this understanding of postural and global muscles and how they support our body through movement, let’s look at how we can create movement patterns that ensure our postural muscles are activated and doing their share of the work. Here are two examples you can work into your daily routine;


The McGill "Big Three" to activate your postural muscles

Simple Postural Routine | Complete the routine each morning or before your usual exercise routine.


1.Curl Up

  • Lie down on your back. Extend one leg and bend the knee of the other leg.

  • Put one hands under the lower back to maintain the natural arch of your spine and the other to support your head if required.

  • Pull your head, shoulders and chest off the floor, as though they were all locked together. Lift them up as one unit. Keep your back in neutral position. Don’t tuck your chin or let your head tilt back. Hold for 10 seconds.

  • Slowly lower yourself down. Do half of the repetitions with your left leg bent and half with your right leg bent.

  • Plank (high or low)

2. Side Plank

  • Lie on your side, with your forearm on the floor and elbow underneath your shoulder. Place your hand on the opposing shoulder to stabilize your torso. Pull your feet back so the knees are at a 90-degree angle.

  • Lift the hips off of the floor and hold for 10 seconds. Try to maintain a straight line from your head down to your knees. Make sure that your hips are in line with the rest of your body. When completed turn over to other side. (Optional: For a greater challenge, straighten the legs instead of bending them).

  • Increase the hold from 10 - 30 seconds as you build strength

3. Bird Dog

  • Assume a hands-and-knees position on the floor.

  • Raise the left arm forward while simultaneously extending your right leg back until both are parallel to the ground. Ensure that hips are aligned with the torso and not tilted to one side. Hold for 10 seconds. Repeat on the other side.

  • Repeat 6 times on each side

  • If you feel you are creating an arch in your back or losing balance, keep both hands on the ground and extend one leg at a time until you have developed greater strength


Wobble Board

The sit/stand desk phenomenon has meant that many people are now standing while working, but is this enough? Firstly, standing or sitting for the full days work isn’t healthy. It is better to move between the two patterns every hour or so. It is actually the movement that is providing benefit as much as the resting position. Moving from one position to the other activates our postural muscles.


Taking that to the next level is to introduce a wobble board. Creating instability that the body needs to address activates the postural muscles. Freeman & Wyke discovered in the 1960's, the connection between ankle instability and low back pain. Both being signs that the postural muscles are not doing their job.


Don't let your postural muscles take a back seat and make the global muscles do more than their fair share!


References:

  1. The Janda Approach: http://www.jandaapproach.com/about/

  2. Janda V. 1968. Postural and phasic muscles in the pathogenesis of low back pain. Proceedings of the 11th Congress of International Society of Rehabilitation of the Disabled”, Dublin, Ireland. Pp 553-54.

  3. McGill SM. Low Back Disorders: Evidence Based Prevention and Rehabilitation(2nd ed). Champaign, IL: Human Kinetics Publishers, 2007.

  4. Freeman MA, Dean MR, Hanham IW. 1965. The etiology and prevention of functional instability of the foot. J Bone Joint Surg Br 47(4):678-85.

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