SUPPLEMENT: DESCRIPTION OF THE EXERCISES
General description of the exercises
In each exercise, except “extension on elbows”, the subject was sitting on a chair with the back supported, the hands resting in a relaxed position on the thighs, with the cervical spine in a neutral position. The therapist was standing behind or on the side of the subject and applied resistance against the neck dorsally at the level of a vertebral arch or ventrally at the level of one transverse process (unilateral) or at the head. The subject was asked to counteract the resistance keeping their head and neck in the neutral position. Thus, the exercises were intended to be isometric.
Traction and Compression:Traction
/ Rationale:
Traction is a movement that pulls the head and the neck away from the thorax along the longitudinal axis of the spine. This movement flattens the physiological cervical lordosis (Panjabi et al., 1978). Anatomically, the deep cervical extensors should be able to maintain the lordosis as they attach directly to the vertebra and lay dorsal to the axis of movement for extension/flexion. In addition, as the head is pulled away from the thorax, all muscles between the head and the thorax are expected to be active.
Procedure:
The therapist was standing behind the subject and placed the palms of his hand on the occiput below the subject’s ears. In order to keep his hands still, he placed his forearms on the subject’s shoulders without applying pressure. With both hands, the therapist gently pushed the head vertically towards the ceiling. Upon feeling the first resistance to the movement he asked the subject to resist saying: “Please keep your head still and don’t let me pull it away.”
Compression
/ Rationale:
Compression is a movement that pushes the head and the neck towards the thorax along the longitudinal axis of the spine. Compression increases the physiological lordosis of the cervical spine. Anatomically, the deep cervical flexor muscles should be able to prevent an increase in the lordosis with their attachments directly on the vertebrae. The superficial flexors and all extensor muscles may be co-activated.
Procedure:
The therapist was standing behind the subject and placed both hands on top of the subject’s head. In order to keep his hands still, he placed his forearms on the subject’s shoulders without applying pressure. With both hands, the therapist gently pushed the subject’s head vertically downwards/caudally and asked the subject to resist saying: “Please keep your head still and don’t let me push it down.”
Extension exercises:
Extension at the occiput
/ Rationale:
Anatomically, the superficial cervical extensor muscles with attachments to the occiput are best suited to perform head extension. Activation of the deep cervical extensors is also expected to provide cervical spine support.
Procedure:
The therapist was standing on the left side of the subject and stabilized the subject’s trunk by fixing the left shoulder. The therapist pushed the head of the subject ventrally and slightly cranially, approximately parallel to the facet plane of the zygapophyseal joints. Simultaneously he asked the subject to resist saying: “Please keep your head still and don’t let me push it forward.”
Extension at C1
/ Rationale:
Anatomically, the deep cervical extensor muscles, attaching directly to the vertebrae, are best suited to extend the neck backwards. Since the resistance was applied at the of level C1, it was expected that the semispinalis cervicis muscle at the level of C2 would be more active compared to the level C5. As the head is destabilized, activation of the superficial cervical extensors (including splenius capitis) is also expected.
Procedure:
The therapist was standing on the left side of the subject and stabilized the subject’s trunk by fixing the left shoulder. The therapist placed his thumb and index finger over the neck at the level of the vertebral arch of C1 and pushed ventrally, and slightly cranially, approximately parallel to the facet plane of the zygapophyseal joints. Simultaneously he asked the subject to resist saying: “Please keep your neck still and don’t let me push it forward.”
Extension at C4
/ Rationale:
Anatomically, the deep cervical extensor muscles, attaching directly to the vertebrae, are best suited to extend the neck backwards. Since the resistance is applied at the level of C4, the semispinalis cervicis muscle should be more activated at the level of C5 compared to C2. As the head is destabilized, activation of the superficial cervical extensors (including splenius capitis) is also expected.
Procedure:
The therapist proceeded exactly as when applying resistance at the level of C1 however, for this exercise the resistance was applied at the level of C4.
Flexion exercises:
Flexion at the occiput
/ Rationale:
Resistance applied at the forehead may induce extension in the upper and the lower cervical spine. Thus a coactivation of the extensor muscles together with the flexor muscles may be expected(Fernández-de-las-Peñas et al., 2008). Since the resistance is applied at the forehead, the primary coactivationmay be from the superficial cervical extensors (e.g. splenius capitis) which attach directly to the occiput.
Procedure:
Standing anterolateral to the subject, the therapist stabilized the subject’s trunk by fixating the left shoulder. The therapist grasped the head with his ventral hand placing its ulnar side below the ear and holding the head at the other side with his chest. Then he pushed the forehead dorsally asking the subject to resist saying: “Please hold your head calm and don’t let me push it backward.”
Flexion at C1
/ Rationale:
The unilateral resistance at the anterior aspect of the transverse process of C1 should destabilize this level and the levels below. The semispinalis cervicis muscle in this region should be able to counteract the movement stimulus more so that the splenius capitisattaching to the occiput.
Procedure:
Still standing anterolateral to the subject, the therapist stabilized the subject’s trunk by fixating the left shoulder. The therapist placed the hypothenar of his left hand on the anterior aspect of the transverse process of C1 and his chest against the left side of the subject’s head. The therapist applied pressure over the transverse process dorsally asking the subject to resist saying: “Please keep your neck still and don’t let me push it backward.”
Flexion at C4
/ Rationale:
The unilateral resistance at the anterior aspect of the transverse process of C4 should destabilize this level and less so levels above. It is expected that the activity of the semispinalis cerviciswould be greater at the level of C5 compared to the level C2.
Procedure:
The therapist proceeded exactly as before when applying resistance at level C1 but with the pressure applied over the level of C4.
General rationale for the extension on elbows exercises:
Extension on elbows without additional resistance
/ Rationale:
Anatomically, the deep cervical extensors with direct attachments to the vertebrae should be activate in this position to resist the flexion force induced by the weight of the head. The superficial extensors (e.g. splenius capitis) that attach to the occiput are also expected to be active(Jull et al., 2008). The semispinalis cervicis muscle is expected to show greater activation at the level of C5 compared to C2 due to the longer load lever arm of the head at C5 compared to C2. There should however be no difference in the activation of splenius capitis at both spinal levels since this muscle only attaches to the head.
Procedure:
The subject is standing in front of a table propped up on both forearms. The head, neck and trunk are in a neutral position. The therapist stands beside the subject to monitor the correct position.
Extension on elbows with resistance at C4
/ Rationale:
The addition of manual resistance applied to C4 is expected to enhance the activation of the deep cervical extensors,e.g. semispinalis cervicis, at the level of C5 but not at C2 since the vertebrae caudal to C4 are pushed in a ventral-cranial direction while the head and the upper cervical spine maintain a similar position as in the previous exercise.
Procedure:
The subject is standing in front of a table propped up on both forearms. The head, neck and trunk are in a neutral position. The therapist places the thumb and index finger over the neck at the level of the vertebral arch of C4, and applies pressure ventrally, and slightly cranial, approximately parallel to the facet plane of the zygapophyseal joints. Simultaneously the therapist asked the subject to resist saying: “Please keep your neck still and don’t let me push it forward.”
REFERENCES
Fernández-de-las-Peñas C, Falla D, Arendt-Nielsen L, Farina D. Cervical muscle co-activation in isometric contractions is enhanced in chronic tension-type headache patients. Chephalalgia 2008; 28: 744-751.
Jull G, Sterling M, Falla D, Treleaven J, O'Leary S. Whiplash, Headache, and Neck Pain: Research-Based Directions for Physical Therapies: Research-based directions for physical therapies. Churchill Livingstone (Elsevier), Edinburgh 2008
Panjabi MM, White III AA, Keller D, Southwick WO, Friedlaender G. Stability of the cervical spine under tension. Journal of Biomechanics 1978; 11: 189-197.
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