The strength-endurance exercise consisted of a progressive
resistance exercise program for the neck muscles, especially
the superficial neck flexor and extensor muscles
(SCM, AS and CE). Neck flexion and extension were performed
in the supine and prone positions, respectively, with
the head supported in a comfortable resting position. Subjects
slowly moved the head and neck through the total range
of motion avoiding discomfort or symptom reproduction.
This exercise program included two phases. The first phase
of 4 weeks and the second of 8 weeks were recommended
for initiating a weight program in untrained individuals28)
.
In phase one, each subject performed 12–15 repetitions with
a weight that they could lift 12 times on the first training
session (12 repetitions maximum) and progress to 15 repetitions.
They were maintained at this level for 4 weeks. In
phase two, subjects performed 3 sets of 15 repetitions of the
initial 12 repetitions at maximum load with one minute rest
interval between sets.
The craniocervical flexion exercise consisted of a low
load exercise for the cranio-cervical flexor muscles. Subjects
lay supine and slowly moved the head to the inner
range of cranio-cervical flexion, guided by feedback from
an air filled pressure sensor placed suboccipitally behind
the neck and inflated to a baseline pressure of 20 mmHg.
Subjects moved the head to increase the pressure to between
22 to 30 mmHg; and maintained this position for
10 seconds in 15 repetitions. The subjects maintained the
10-second contraction with no pain. Ten seconds rest was
allowed between each contraction. The targets of this exercise
are the deep flexors of the upper cervical region, the
longus capitis and colli, rather than the superficial flexors,
which flex the neck but not the head.
The combined exercise group performed both strengthendurance
and cranio-cervical flexion exercises. First, subjects
lay supine and performed the cranio-cervical flexion
exercise. A five minute rest was then taken before performing the strength-endurance exercise.
Subjects in each group performed exercise every day for
12 weeks and kept a log book for monitoring. Exercise compliance
in this study was over 80% in all groups.
VAS and NDI were recorded before a copy-typing task.
The sEMG were recorded in two sessions during a copytyping
task lasting 5 minutes. After exercise training of 12
weeks, VAS, NDI and sEMG were recorded again for all
subjects. For the copy-typing task, subjects sat at a standard
office desk on an adjustable office chair. They could
adjust the chair and desk before the test to obtain the most
comfortable position, but they were not allowed to move
between tasks. The visual display monitor and keyboard
were positioned directly in front of the subjects for the typing
tasks. A copy-typing task was chosen over typing from
a document holder to eliminate movement of the head or
the need to change head position from document to screen
as needed for eye-hand coordination activities. The copytyping
task was performed continuously for 5 minutes.
After finishing data collection, subjects in the control
group were advised to perform both the strength-endurance
and cranio-cervical exercises. In the strength-endurance
exercise group, subjects were trained in how to perform
deep cervical flexor muscle (CCF exercise) and subjects
in the CCF exercise group were trained in how to perform
strength-endurance exercise.
The statistical analyses of the data were performed using
SPSS version 17.0. The VAS, NDI scores and the averages
of root mean square (RMS) sEMG values were used in the
analyses. Statistical significance was accepted for values of
p