Core Stability

Core stability training has been a buzzword for some time in the athletic and personal training world and it has been interesting to see the interpretation by some practitioners. Kibler and colleagues (2006) provide a good summary of some of the literature on the subject and provide a clear set of assessment and training protocols to restore or improve core function, which can be applied to athletic and general populations alike. Be aware there is a bit of anatomy and kinesiology in this one. Should you have questions regarding specifics of the anatomy or kinesiology please feel free to email questions to:Core Stability Questions

What is the core?

Core comprises of the spine, hips, upper leg and abdominal structures. The muscles in this region are key to transferring energy from the large body segments to small body segments. The central location of the elements of the core allows the distal (lower legs and arms) to perform movements required in athletic activities, providing proximal stability for distal mobility. The core is crucial in almost all activities of the extremities such as kicking, throwing and running. Therefore injuries to the extremities should be assessed with consideration of core function.

Definition of Core Srtability

“The ability to control the position and motion of the trunk over the pelvis and leg to allow optimum production, transfer and control of force and motion to the terminal segment in integrated kinetic chain activities”

In other words the core positions and holds the body in the optimal position to allow athletic movements to occur in an optimal fashion. This will improve movement efficiency and power while decreasing the chance for injury to the lower back and other areas of the body.

Anatomy and Physiology

Most of the major prime movers of the body attach to the core (consider latissimus dorsi of the back or the hip flexors and extensors and knee flexors and extensors). The core muscles themselves are numerous and varied in their type and function, some being very small and spanning just one joint (for example multifidus providing segmental spinal stabilization to very local and specific parts of the spine) to large multi-joint, multi-segment muscles such as psoas major, spanning the hip, femur and lumbar spine. It is also important to consider the muscles of the abdomen and their vital role in creating a strong central “cylinder” particularly when the shape of transversus is appreciated wrapping around the abdomen like a corset. The obliques and rectus abdominus are also vital in contributing direction specific strength.

Before the movement of large body segments the deep core muscles activate increasing the pressure of the contents of the abdomen and thus supporting the lumbar spine creating a stable foundation. Crucial to the functioning of the hip and pelvis are the major muscles of the area, hip flexors and extensors which provide not only great power and locomotive actions in sports and daily life but also serve to fix the pelvis and thigh. However this power cannot be used as effectively without a well functioning core. These muscles are even included in throwing activities, and contribute approximately 50% of the total force delivered through the arm, this is assisted by the thoracolumbar fascia that connects the legs to the arms.

Muscle action is based upon preprogrammed muscle activation patterns that improve with practice. These activation patterns are dependant either on limb length in single joint activities or force when performing actions based on a number of joints. Evidence shows that in a high-speed arm motion such as a throw the intial activation comes from the calf muscles (Gastrocnemius and Soleus) of the opposite leg to the throwing arm. In addition baseball-throwing activity has been shown to initiate in the opposite external oblique. By being able to develop more force at the right time in the muscles that are close to trunk such as the “typical” core muscles and stabilizers of the shoulder such as rhomboids and trapezius the muscles of the arm can concern themselves less with force generation and more with precision making for more accurate throwing with greater efficiency. Ultimately this will result in better performance and less injury. This is demonstrated in the calf muscles as well where activation of the muscles close to the body increases plantar flexion (pointing the toes) strength by 26%.

Things to look for

In developing a core rehabilitation or training program for the athlete is crucial to understand their specific issues to get the best out of their training time. A few simple tests can aid this process. While objective assessment is difficult and various practitioners have described many techniques, Kibler and colleagues (2006) have found the following to be particularly useful.

Standing on one leg:

The athlete drops the hip on the contralateral leg – Indication weakness in the deep core (Transversus, internal obliques).

The athlete “corkscrews” to bring the hips over the leg they are standing on – Indication of hip abductor weakness (quadratus lumborum and gluteus medius and minimus) predominantly.

There are no standard tests described in the literature however single leg balancing is a good starting point looking for the conditions described above. This can be progressed to single leg squatting once again assessing the movement deviations described above. Three plane testing can be done by asking the athlete to stand side on proximately 8cm from a wall with the weight born on the inside leg. The athlete should be able to lightly touch the shoulder to the wall without losing balance. This test can be repeated to the front and back giving a good indication of eccentric control and strength.

Rehabilitation

Athletic requirements of the core are as for most muscles incorporating flexibility, balance, strength and endurance. Initial work should focus on specific weaknesses, poor movement patterns and inflexibilities. Progression should move quickly to global movement patterns in sport specific movements addressing the entire kinetic chain as described in the anatomy and physiology section.

The rehabilitation protocol should begin by addressing the deep core muscles (tranversus, multifidus and quadratus lumborum) due to their direct attacment to the pelvis and spine, which make them most responsible for the central portion of core stability. Side planks and isometric trunk rotation are good exercises to achieve these goals.

To progress to extremity stability incorporate forward and side lunges into the program. For the upper body, begin to introduce pulling movements initially with both arms then single arms and eventually single arm and single leg moving from ipsilateral (the left arm and leg) to contralateral (right arm, left leg). Cue the athlete to put their elbows in their back pocket will assist in achieving the desired scapular position.

Rehabilitation should avoid using movements in one plane or that isolate single muscles. This may be appropriate early in the training program but should be moved on quickly to more functional exercises. This will ensure a rapid return of development of normal biomechanics. These functional exercises should be begun with the extremity (arm or leg) close to the body and progressed to bring the extremity further from the body. The philosophy of core training and rehabilitation should be to build a base of stability and strength and progressed to develop control in increasingly distal (further from the centre) movements. The concept of the core becoming the “engine” of force generation through out the body.

In summary the core can provide proximal strength to maximize distal mobility. This requires the muscles of the core to switch on at the right time and fixate the pelvis and spine with as much force as is required to hold the base stable so the extremities can achieve the desired action in the most efficient way.

Practitioners should have a detailed understanding of the anatomy and kinesiology of the core and related structures to best assess issues inherent to specific athletes and develop the best rehabilitation and training programs. For this it is best to work with a qualified strength and conditioning coach or physiotherapist.

Reference

Designed by Young Graphic Designer