Load moments and myoelectric activity when the cervical spine is held in full flexion and extension.

Abstract Sustained joint load in extreme positions (namely maximally flexed or extended positions) has been described as causing pain. The aim of the present study is to analyse eight different sitting work postures with respect to extreme positions, and to assess the mechanical load and the levels of muscular activity arising in defined extreme positions of the cervical spine. Ten healthy female workers from an electronics plant took part in laboratory experiments. For seven of these, levels of neck and shoulder muscular activity in sitting postures with the cervical spine in different manually-adjusted extreme positions were recorded using surface electrodes. Loading moments of force about the bilateral motion axis of the atlanto-occipital joint (Occ-C1) and the spinal cervico-thoractc motion segments (C7-T1) were calculated. Extreme or almost extreme positions occurred in sitting postures with the thoracolumbar back inclined slightly backwards or with the whole spine flexed. Electromyographic (EMG) act...

[1]  S. Skoglund,et al.  On the reflex effects from the knee joint of the cat. , 1960, Acta physiologica Scandinavica.

[2]  H. R. Lissner,et al.  Biomechanics Of Human Motion , 1962 .

[3]  Function of longus colli and longissimus cervicis muscles in man. , 1966 .

[4]  P. A. van Wely,et al.  Design and disease , 1970 .

[5]  J. Basmajian,et al.  The integrated roles of longus colli and sternocleidomastoid muscles: An electromyographic study , 1973, The Anatomical record.

[6]  G. Elfström,et al.  Lumbar disc pressure and myoelectric back muscle activity during sitting. I. Studies on an experimental chair. , 1974, Scandinavian journal of rehabilitation medicine.

[7]  J. Basmajian,et al.  The functions of semispinalis capitis and splenius capitis muscles: An electromyographic study , 1974, The Anatomical record.

[8]  B Jonsson,et al.  Endurance limit of force in long-term intermittent static contractions. , 1977, Scandinavian journal of work, environment & health.

[9]  Manohar M. Panjabi,et al.  Clinical Biomechanics of the Spine , 1978 .

[10]  C. Arnoldi,et al.  The effect of joint position on juxta-articular bone marrow pressure. Relation to intra-articular pressure and joint effusion--an experimental study on horses. , 1980, Acta orthopaedica Scandinavica.

[11]  E. Grandjean,et al.  Constrained postures in accounting machine operators , 1980 .

[12]  G Borg,et al.  Discomfort and pain from loaded passive joint structures. , 1983, Scandinavian journal of rehabilitation medicine.

[13]  M Hagberg,et al.  Trunk posture and load on the trapezius muscle whilst sitting at sloping desks. , 1984, Ergonomics.

[14]  On hip and lumbar biomechanics. A study of joint load and muscular activity. , 1984, Scandinavian journal of rehabilitation medicine. Supplement.

[15]  J Ekholm,et al.  Intensity and character of pain and muscular activity levels elicited by maintained extreme flexion position of the lower-cervical-upper-thoracic spine. , 2020, Scandinavian journal of rehabilitation medicine.

[16]  G. Németh,et al.  Effects of changes in sitting work posture on static neck and shoulder muscle activity. , 1986, Ergonomics.