In the ultra competitive world of sport, where coaches and practitioners are constantly searching for ways to differentiate ourselves from the pack, we are often too quick to adopt new concepts without first questioning there credibility. This seems to be especially so with the ‘core stability’ trend that has hit so many gyms, physiotherapy clinics and other fitness studios.
The majority of the exercises that apparently improve ‘core stability’ involve lying supine, either on a Swiss ball or the floor, with the client instructed to contract his transverse abdominis before lifting a limb or body part. Many of these exercises are performed in a slow, controlled manner, with very little emphasis on ballistic movements.
These ‘core stability’ exercises have been proposed to increase performance and decrease injuries. However there is somewhat of a deficit of scientific evidence to support these claims.
For those of you who are not aware of the term ‘specificity’ I will enlighten you for the sake of the argument. Principally, when training or rehabilitating people it is often said that the selected exercises should be activity specific (the Principle of Specificity). Obviously the most specific training is the activity itself; however by blending exercises intrinsic to aspects of the chosen activity, based on the level of the athlete and the stage of training, various levels of specificity can be achieved.
If we take sport of Athletics, specifically sprinting, into consideration it is evident that sprinting is a fast, ballistic activity generating very large forces: relatively high mass moving with exceptionally high acceleration and velocity.
Are the forces generated in core stability exercises sufficiently preparing athletes to cope with their environment?
It is safe to say that movements at slow speeds do not automatically enhance ones ability to produce movements at faster speeds. Studies by Moffroid & Whipple found that low velocity isokinetic training improves low velocity strength but does little to increase high velocity strength. The majority of core stability exercises prescribed by various trainers/therapists are slow and controlled, whilst many would be classified as stationary.
It is often said that these exercises increase the strength of ones core (i.e. trunk). However it is apparently that the force of a contraction is a function of the load. As we all know a load that is too low will not increase strength significantly. Science shows us that the load lifted influences the adaptation. Therefore movements with a low load do not necessarily enhance one’s ability to perform the movement with heavier loads.
It has been proven that training is posture specific. That is to say that the closer the movement in training represents the movement being tested, the greater the increase in performance. In other words if you are training for an activity that requires mostly an upright posture, train in an (mostly) upright posture!
Further more, the dogmatic distinction between stabilisers and mobilisers is arbitrary; there exists no clear distinction between the two. Each muscle can have a significantly different function in different movements and even at different times in the same movement). A simple example of this is while sitting upright and rotating, the obliques are used mainly as mobilisers, while in the pushup position they are being used as stabilisers.
The claim that core stabilising exercises are the best method of strengthening the transverse abdominis for sporting application is fallacious and unfounded. Whilst the transverse abdominis is an integral part of the overall stability of the trunk, the most activation occurs during forceful exhalation. This would suggest weightlifting exercises incorporating the Valsalva technique will strengthen the transverse abdominis and provide specific application to sprinting.
Whilst certain ‘core stability’ exercises might be beneficial to some circumstances, there is insufficient evidence for, and plenty of evidence against using core stability exercises for performance enhancement and injury prevention in the sporting arena.