The Effects of Muscle Characteristics on the Control of Shoulder Complex During Functional Movements

Superimposition of electrical stimulation during voluntary contractions is used to produce functional movements in individuals with central nervous system impairment, to evaluate the ability to activate a muscle, to characterize the nature of fatigue, and to improve muscle strength during postsurgical rehabilitation. Currently, the manner in which voluntary contractions and electrically elicited forces summate is not well understood. The objective of the present study is to develop a model that predicts the forces obtained when electrical stimulation is superimposed on a volitional contraction. Quadriceps femoris muscles of 12 able-bodied subjects were tested. Our results showed that the total force produced when electrical stimulation was superimposed during a volitional contraction could be modeled by the equation T = V + S[(MaxForce − V)/MaxForce]N, where T is the total force produced, V is the force in response to volitional contraction alone, S is the force response to the electrical stimulation alone, MaxForce is the maximum force-generating ability of the muscle, and N is a parameter that we posit depends on the differences in the motor unit recruitment order and firing rates between volitional and electrically elicited contractions. In addition, our results showed that the model predicted accurately (intraclass correlation coefficient ≥0.97) the total force in response to a wide range of stimulation intensities and frequencies superimposed on a wide range of volitional contraction levels. Thus the model will be helpful to clinicians and scientists to predict the amount of stimulation needed to produce the targeted force levels in individuals with partial paralysis.

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Improving outcome of sensorimotor functions after traumatic spinal cord injury

F1000Research ◽

10.12688/f1000research.8129.1 ◽

2016 ◽

Vol 5 ◽

pp. 1018 ◽

Cited By ~ 2

Author(s):

Volker Dietz

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Animal Models ◽

Technical Assistance ◽

Cord Injury ◽

Descending Input ◽

Muscle Activations ◽

Clinical Conditions ◽

Functional Movements ◽

Experimental Stage

In the rehabilitation of a patient suffering a spinal cord injury (SCI), the exploitation of neuroplasticity is well established. It can be facilitated through the training of functional movements with technical assistance as needed and can improve outcome after an SCI. The success of such training in individuals with incomplete SCI critically depends on the presence of physiological proprioceptive input to the spinal cord leading to meaningful muscle activations during movement performances. Some actual preclinical approaches to restore function by compensating for the loss of descending input to spinal networks following complete/incomplete SCI are critically discussed in this report. Electrical and pharmacological stimulation of spinal neural networks is still in the experimental stage, and despite promising repair studies in animal models, translations to humans up to now have not been convincing. It is possible that a combination of techniques targeting the promotion of axonal regeneration is necessary to advance the restoration of function. In the future, refinement of animal models according to clinical conditions and requirements may contribute to greater translational success.

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Specificity of recumbent cycling as a training modality for the functional movements; sit-to-stand and step-up

Clinical Biomechanics ◽

10.1016/j.clinbiomech.2007.06.006 ◽

2007 ◽

Vol 22 (10) ◽

pp. 1104-1111 ◽

Cited By ~ 8

Author(s):

A. Kerr ◽

D. Rafferty ◽

F. Moffat ◽

G. Morlan

Keyword(s):

Sit To Stand ◽

Training Modality ◽

Functional Movements

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Current concepts on biomechanics of the shoulder complex

Physiotherapy ◽

10.2478/v10109-010-0010-2 ◽

2009 ◽

Vol 17 (2) ◽

Author(s):

Jarosław Skolimowski ◽

Beata Skolimowska ◽

Ewa Demczuk-Włodarczyk ◽

Katarzyna Barczyk ◽

Sławomir Winiarski ◽

...

Keyword(s):

Shoulder Complex

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Spinal and Shoulder Girdle Range of Motion in Elite Female Volleyball Athletes

Polish Journal of Sport and Tourism ◽

10.1515/pjst-2015-0021 ◽

2015 ◽

Vol 22 (3) ◽

pp. 143-147

Author(s):

Arletta Hawrylak ◽

Dorota Wojna ◽

Krystyna Chromik

Keyword(s):

Range Of Motion ◽

Body Mass ◽

Body Height ◽

Shoulder Girdle ◽

Average Height ◽

Spine Mobility ◽

Shoulder Complex ◽

Average Body Mass ◽

Average Body ◽

Group 1

Abstract Introduction. Doing asymmetric sports when one suffers from body asymmetry may cause body posture disorders. The aim of the study was to assess the spinal and shoulder complex mobility of professionally trained volleyball athletes compared to that of their peers who do not practise any sports. Material and methods. The study involved 60 participants divided into two groups. Group 1 consisted of 30 girls aged 14 years. The average height in the group was 176.37 ± 6.29 cm, and the average body mass was 64.53 ± 7.12 kg. Group 2 consisted of 30 girls aged 15.6 ± 1.12 years who did not practise any sports. The average body height in this group was 159.37 ± 3.33 cm, and the average body mass was 51.83 ± 4.03 kg. The dominant limb was defined on the basis of lateralization. The spinal range of motion was measured by means of a Saunders digital inclinometer, and the shoulder complex range of motion was examined using the goniometric method. Means and standard deviations were calculated, and Student’s t-test was applied in order to determine the differences between the two groups. Results. The differences in the values obtained in the two groups for the spinal range of motion in the sagittal plane were statistically significant only for the range of lumbar spine bending and extension. It was found that group 1 had a higher range of spine mobility in the frontal and transverse planes, and the differences were statistically significant in all the assessed ranges towards the dominant limb. An analysis of the shoulder girdle range of motion in the groups revealed that the differences were also statistically significant in all of the examined ranges. Conclusion. Professional volleyball practice can cause an increase in spine flexibility in most of its ranges, and the shoulder girdle range of motion in female volleyball players can exceed population norms, especially for the upper dominant limb.

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Ergonomic Consideration in Pillow Height Determinants and Evaluation

Healthcare ◽

10.3390/healthcare9101333 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1333

Author(s):

Jia-Xing Lei ◽

Peng-Fei Yang ◽

Ai-Ling Yang ◽

Yan-Feng Gong ◽

Peng Shang ◽

...

Keyword(s):

Cervical Spine ◽

Muscle Activity ◽

Sleep Problems ◽

Comprehensive Evaluation ◽

Sufficient Evidence ◽

Health Issues ◽

Body Dimension ◽

Current Trends ◽

Shoulder Complex ◽

Cervical Spine Alignment

(1) Background: Sleep problems have become one of the current serious public health issues. Pillow height affects the alignment of the cervical spine and is closely related to the mechanical environment of the cervical spine. An appropriate pillow height can provide adequate support for the head and neck to reduce the stress in the cervical spine and relax the muscles of the neck and shoulder, thereby relieving pain and improving sleep quality. (2) Methods: We reviewed the current trends, research methodologies, and determinants of pillow height evaluation, summarizing the evidences published since 1997. In particular, we scrutinized articles dealing with the physiological and mechanical characteristics of the head-neck-shoulder complex. (3) Results: Through the investigation and analysis of these articles, we presented several quantitative and objective determinants for pillow height evaluation, including cervical spine alignment, body dimension, contact pressure, and muscle activity. The measurement methods and selection criteria for these parameters are described in detail. However, the suggested range for achieving optimal cervical spine alignment, appropriate pressure distribution, and minimal muscle activity during sleep cannot yet be identified considering the lack of sufficient evidence. Moreover, there remain no firm conclusions about the optimal pillow height for the supine and lateral positions. (4) Conclusions: A comprehensive evaluation combining the above determinants provides a unique solution for ergonomic pillow design and proper pillow height selection, which can effectively promote the public sleep health. Therefore, it is necessary to develop a reasonable algorithm to weigh multiple determinants.

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