Maximal isometric muscle strength of the cervical spine in healthy volunteers
ABSTRACT To describe the maximal isometric neck muscle strength in healthy Chinese volunteers, in six different directions, as measured by a Multi Cervical Rehabilitation Unit.
A standardized cross-sectional observational study.
A university rehabilitation unit.
Ninety-one healthy volunteers aged 20-84.
During the measurement the subject was instructed to do three consecutive steady contractions as hard as possible, with a 10-second rest in between each contraction and a 2-minute rest between different directions. The peak isometric strength for each of the six directions (flexion, extension, lateral flexions, protraction and retraction) was calculated.
No significant difference was found in muscle strength between different age groups. Isometric muscle strength in the direction of right lateral flexion was significantly greater than that to the left in men (p = 0.030), but no difference was found in women (p = 0.297). Isometric strength in all directions in men was 1.2-1.7 times that in women (all p < 0.028). Correlations between physical measurements (height and weight) and strength values were all insignificant in both genders.
Men have approximately 20-70% greater isometric neck muscle strength than women. Both men and women can maintain high levels of cervical muscle strength in six different directions up to their seventh decade. There is no significant correlation between physical measurements and isometric neck muscle strength.
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ABSTRACT: Introduction This study aimed to determine the reference values for range of motion (ROM) and cervical isometric strength in a healthy population control group and to assess the influence on it variables such as gender, age, anthropometrical measures and physical activity. Methods and background Data: Sample: 80 healthy persons. Protocol: The Multi-Cervical Unit (MCU) records ROM and cervical isometric strength specific angle and coefficient of variation. These data were then compared with the American Medical Association values and values obtained by the Multi Cervical Unit (MCU) database. Body mass index, cervical circumference and physical activity were also recorded. Results The ROM values obtained are close to the American Medical Association values. The force values found in our series are below those of the MCU. No significant difference were found regarding the influence of gender on ROM. A strong statistical association was observed in regards to strength. Influence of age on ROM is only significant in men. Conclusions Significant differences in the ROM values were not found between both genders. Therefore, it is not necessary to use specific gender differentiation. The association between gender and isometric cervical spine strength is highly significant. The relationship between physical activity and an increase of the cervical strength has been verified.Rehabilitación 01/2013; DOI:10.1016/j.rh.2013.09.004
Article: Biomecánica en Medicina Laboral
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ABSTRACT: ABSTRACT Objectives Whiplash Associated Disorders (WADs), or 'whiplash injuries', due to low severity vehicle crashes are of great concern in motorised countries and it is well established that the risk of such injuries is higher for females than for males, even in similar crash conditions. Recent protective systems have been shown to be more beneficial for males than for females. Hence there is a need for improved tools to address female WAD prevention when developing and evaluating the performance of whiplash protection systems. The objective of this study is to develop and evaluate a finite element model of a 50(th) percentile female rear impact crash test dummy. Methods The anthropometry of the 50(th) percentile female was specified based on literature data. The model, called EvaRID (Eva - female/RID - Rear Impact Dummy), was based on the same design concept as the existing 50(th) percentile male rear impact dummy, the BioRID II. A scaling approach was developed and the first version, EvaRID V1.0, was implemented. Its dynamic response was compared to female volunteer data from rear impact sled tests. Results The EvaRID V1.0 model and the volunteer tests compared well until ∼250 ms of the head and T1 forward accelerations and rearward linear displacements, and of the head rearward angular displacement. Markedly less T1 rearward angular displacement was found for the EvaRID model compared to the female volunteers. Similar results were received for the BioRID II model when comparing simulated responses with experimental data under volunteer loading conditions. The results indicate that the biofidelity of the EvaRID V1.0 and BioRID II FE models have limitations, predominantly in the T1 rearward angular displacement, at low velocity changes (7 km/h). The BioRID II model was validated against dummy test results in a loading range close to consumer test conditions (EuroNCAP) and lower severity levels of volunteer testing were not considered. Conclusions The EvaRID dummy model demonstrated the potential of becoming a valuable tool when evaluating and developing seats and whiplash protection systems. However, updates of the joint stiffness will be required to provide better correlation at lower load levels. Moreover, the seated posture, curvature of the spine and head position of 50(th) percentile female occupants needs to be established and implemented in future models.Traffic Injury Prevention 02/2014; DOI:10.1080/15389588.2014.885647 · 1.29 Impact Factor