The aim of core stability training is to effectively recruit the trunk musculature and then learn to control the position of the lumbar spine during dynamic movements. The information presented on this page is based on an article written by Raphael Brandon which was first published in the Sports Injury Bulletin.
The deep trunk muscles, Transversus Abdominis (TA), multifidus (MF), Internal Oblique (IO), paraspinal, pelvic floor, are key to the active support of the lumbar spine. The co-contraction of these muscles produce forces via the "theracolumbar fascia" (TLF) and the "intra-abdominal pressure" (IAP) mechanism which stabilise the lumbar spine, and the paraspinal and MF muscles act directly to resist the forces acting on the lumbar spine.
It is not just the recruitment of these deep-trunk muscles, but how they are recruited that is important. Hodges and Richardson (1996) showed that the co-contraction of the TA and MF muscles occurred prior to any movement of the limbs. This suggests that these muscles anticipate dynamic forces which may act on the lumbar spine and stabilise the area prior to any movement. Hodges and Richardson showed that the timing of co-ordination of these muscles was very significant.
Having identified the key muscles and how they act, the next step is to establish how best to train these muscles. As with any type of strength and conditioning training, the training protocol for improving the function of the deep-trunk muscles must be specific to the task required. This specificity of training must take into account the type of contraction, the muscle fibre type and the anatomical position required. By definition, the deep-trunk muscles act as "stabilisers" and are not involved in producing movements, but instead involve static, or isometric, contractions. Furthermore, they must act as stabilisers continuously throughout everyday activities as well as fitness and sport activities, and so require very good endurance of low-level forces. These muscles do not need to be very strong, but they must be correctly co-ordinated and capable of working continuously. In addition, we want these stabiliser muscles to act by holding the lumbar spine in the neutral position, which is the correct alignment of the pelvis that allows for the natural 'S' curve of the spine. These characteristics underpin the following deep-trunk muscle training program.
Core-stability training begins with learning to co-contract the TA and MF muscles effectively as this has been identified as key to the lumbar-support mechanism. To perform the TA and MF co-contraction, you must perform the "abdominal hollowing" technique with the spine in the neutral position. To do this use the following guidelines:
It is absolutely vital that you perform this abdominal hollowing exercise correctly otherwise you will not recruit the TA and MF effectively. Bear in mind the following points:
Once you have mastered the abdominal hollowing lying on your back, practise it lying on your front, four-point kneeling, sitting and standing. In each position get your lumbar spine into neutral before you perform the hollowing movement.
Having learned to recruit the TA and MF muscles correctly in various positions, which can take anything from one session to one month or more, it is time to move onto simple core stability exercises. These exercises may also involve the oblique muscles, other lumbar muscles and gluteals to assist the TA and MF in maintaining the lumbar spine in a stable neutral position.
Lying leg lift stabilisation
Variations include the same exercise with knee lifts up and knee drops out to the side. Again, the aim is to retain a stable lumbar spine in the neutral position as the legs move.
The waiter's bow
These exercises are two examples of learning how to keep the spine in neutral, using slow and controlled, static contractions of the trunk stabiliser muscles. Notice how technique is vital and the aim is to build up the time you are able to maintain good stability.
The ultimate aim of core stability training is to ensure the deep trunk muscles are working correctly to control the lumbar spine during dynamic movements, e.g. lifting a heavy box or running. Therefore it is important that once you have achieved proficiency of the simple core exercises, you must progress on to achieving stability during more functional movements. Try the following two exercises.
Many people wrongly initiate the up movement by pulling their heads and shoulders back first. This extends the lumbar spine, losing the neutral position. Others have problems keeping their pelvis level while performing the lunge. You must learn to use your deep trunk and gluteal muscles to hold your lumbar spine in neutral and pelvis level as you perform the movement up and down. The movement should only come from the leg muscles.
The Press up
Your back should remain still, straight and your lumbar spine in neutral throughout.
These two exercises enable you to learn core stability while performing dynamic movements. By reducing the resistance i.e. doing only half lunges and knee press ups, your are able to focus on the trunk stabilizers and achieving perfect technique rather than working the major muscle groups. The whole essence of core stability training is quality of movement and relaxation. The more you practice, the easier it becomes until you can control your lumbar stability at all times and during complex movements.