Changes in muscular strength based on full cervical flexion

We present our study of influence full cervical flexion position
on the changes in muscle strength of the upper extremities. This position
is typical for a person working on mobile phone or iPad. The purpose of
the study was determination of the connection between change of the head
flexed position and changes in upper extremity muscles strength. The present
study involved 80 healthy volunteers and was performed at the Department
of Morphology in Riga Stradins University, Riga, Latvia. For measurements
we have used the MicroFET2 Hand Held Digital Muscle Tester to determine
the strength of the muscles of the hand and arm (M. abductor pollicis
longus, M. biceps brachii, M. triceps brachii, M. deltoideus). The results of
measurements were then used to analyze the difference in the strength of the
muscles innervated by the spinal cord cervical region (C5–C8 nerves) for the
same person sitting in the vertical position and sitting with the head flexed
maximally. The results of our study support the hypothesis that the changes
in the strength of measured muscles are related to the mechanical distension
of the spinal cord, which leads to changes in spinal cord’s blood supply. The
kyphotic position of the cervical spine during head flexion shows that in the
spinal cord segments C5 and C7 are formed mechanical distension. Using
our statistical study, we can conclude that there is strong relationship in the
strength change in some of the observed muscles between vertical position
and full flexion of head