elbow is flexed to 90˚, and the shoulder joint is abducted to 90˚, to carry the body weight. The free hand is placed on the opposite shoulder to pull it down. For deconditioned individuals, the knees can be bent, or the exercise can be performed standing against a wall. The patient begins by bracing the abdominals to no more than 30% MVC and straightening the torso until the body is supported by the elbow and feet (Fig.2b). This position is held for up to eight seconds, maintaining a good breathing pattern. On return, a rest period of no more than eight seconds will ensure adequate re- oxygenation of the muscles before the movement is repeated. The neuromotor challenge of this exercise can be enhanced by transfer- ring body weight from one elbow to the other rolling the body through 180˚ (Figs.2c-d). This manoeuvre will require three things of the patient: (a) that a brace is maintained during the transition from one side to the other, (b) that the front bridge position is held for up to eight seconds, and, (c) that the body remains in a bridge position throughout. This movement can be repeated continuously, as the transition will allow for adequate re-oxygenation of muscles with each cycle. To meet endurance objectives the exercise should be progressed towards a total time of 2-3 minutes.

Endurance training of the back extensors The exercises given here focus on the thoracic portions of the longissimus and iliocostalis muscles as well as the lumbar region. This is important as the thoracic portions of these muscles have the greatest moment arm and produce the greatest amount of extensor force with minimum compression to the spine. Approximately 74% of

these muscle fibres are slow twitch (15), suggesting an

endurance role. Exercise selection should focus on choosing move- ments that encourage conditioning of the thoracic as well as lum-

bar extensors in neutral spine alignments. The multifidii muscles are also involved in extensor force generation, with small amounts of twisting and side-bending, but only to the extent of providing spe- cific corrections or segmental support. With this in mind, the recent emphasis on isolated multifidus activation during exercise may be misleading. On a final note, the latissimus dorsi (via the thora- columbar fascia attachments to the lumbar spine), is also involved in extensor force generation and stabilisation of the lumbar spine; similarly, the quadratus lumborum appears to be highly involved in frontal plane stabilisation. Both of these muscles should be includ- ed in any spinal stabilisation programme.

The following exercises significantly challenge the back extensors with minimal compression costs to the spine, focussing on the lum- bar and thoracic extensors, as well as the obliques and latissimus dorsi. Both exercises are designed in such a way as to generate sig- nificant axial torque, and thus challenging transverse plane stabili- sation. As previously outlined, these exercises are further enhanced with abdominal bracing.

Opposite arm and leg reach This exercise significantly challenges the back extensors (approxi- mately 25% MVC in the lumbar extensors and 50% MVC in the tho- racic extensors), with tolerable spine loads for most people (16). Abdominal bracing and neutral spine alignment should be empha- sised throughout the exercise.

The patient starts in a kneeling position on hands and knees, with the hands under the shoulders and knees under the hips (Fig.3a). The movement begins with the patient raising the opposite arm and leg simultaneously, ensuring that neither limb moves past horizon- tal (Fig.3b). The objective is to be able to hold this position for up to 10 seconds, maintaining an abdominal brace and neutral spine. The movement is repeated on the other side and continued for up to two minutes (Fig.3c), or as guided by the patients needs and goals. The neuromotor aspect can be challenged further by not allowing the knee and hand to rest on the floor, but continuing the movement on the same side. In this way torsional forces, and subsequent muscle coactivation patterns are sustained, with re- oxygenation of the muscles with each cycle. This version of the exercise is performed for a total of one minute each side. For the deconditioned patient, the exer- cise can be regressed to just an arm raise or leg raise, before moving onto both.

Opposite arm and leg reach Figure 3a Figure 3b

A significant challenge remains in finding suitable exercises that condition rotational movements while sparing the spine. Electromyographic data suggests that stabilisation of the spine during twisting is far more important to the lumbar spine

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