The objective of the study was to determine if different trunk muscles fatigued at a different rate in isometric axial rotation. Rotation is associated with a large number of back injuries. The fatigue behaviour may shed some light on possible reasons for such an association. Subjects were stabilized in an upright seated neutral posture in a specially designed and fabricated device—axial rotation tester such that the rotation could occur only in thoraco-lumbar region. Subjects performed isometric trunk rotation at 60% of their previously measured maximal voluntary contraction for a maximum duration of 2min or less if they could hold no longer. Surface electromyographic (EMG) was measured from seven trunk muscles bilaterally. Power spectra were calculated, the mean median frequency obtained at 10% intervals of the task cycle and compared in time within and between subjects. The EMG amplitudes were significantly different between right and left sides (p<0.01). The initial median frequencies of each muscle were significantly different from the other (p<0.01). The rate of decline of the median frequency for different trunk muscles were different (p<0.01). In isometric trunk rotation different trunk muscles demonstrated a different rate and magnitude of EMG fatigue. The latter is likely to alter the pattern of load sharing between muscles and predisposing musculoligamentous to injury either through stress concentration in deformed tissues or exceeding the strain rate tolerance in fatigue induced jerky motion (micromotion).

A geometric model has been developed to predict the kinematics of the knee from the geometry of its anatomical structures. This model has two important applications in gait analysis. First, it predicts the lines of action of the forces through the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament and at articular contact in the medial and lateral compartments. Second, it predicts the changing position and orientation of the axis of rotation of the knee. In an illustration of its potential, a preliminary version of the model successfully predicted the patterns of tibial rotation and axis orientation that have been observed in experimental studies of normal gait. Once it has been quantitatively validated and refined, the model will be a useful tool in gait analysis, with particular applications in the estimation of forces through the muscles, ligaments and at articular contact in the knee and in the calculation of joint powers.

Two methods of generating the rules for control systems for control of functional electrical stimulation (FES) in locomotion of subjects with incomplete spinal cord injury were studied and qualitatively compared. The aim of the rule-based control system was to synthesize and replace the manual FES-switching function operated by the subject or a skilled physiotherapist. The first method, “hand-crafting” of rules, requires very detailed signal analysis by an experienced person, which may result in systems that are limited either by their functionality or safety for the subject. The second method, i.e. automatic generation of rules through learning from examples by a machine learning program, does not have such limitations because it is capable of learning everything that is presented to it during the training phase. It is obvious that for simple control systems, “hand-crafted” rules are a fast and simple solution, but for complex multichannel FES applications automatic generation of the rules can save many hours of trial-and-error experiments with hand-crafted rules.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTModified Redlich-Kwong equation of state for phase equilibrium calculationsRichard B. SteinCite this: Ind. Eng. Chem. Process Des. Dev. 1982, 21, 4, 564–569Publication Date (Print):October 1, 1982Publication History Published online1 May 2002Published inissue 1 October 1982https://pubs.acs.org/doi/10.1021/i200019a005https://doi.org/10.1021/i200019a005research-articleACS PublicationsRequest reuse permissionsArticle Views171Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

(1990) Comparison of three methods of electrical stimulation for converting skeletal muscle to a fatigue resistant power source suitable for cardiac assistance. Abstract: Twelve dogs were sorted into 3 equal groups, and the in-situ right latissimus dorsi muscle of each dog was stimulated via its motor nerve for a period of 6 weeks. The resulting isotonic contractions were used to pump fluid in an implanted, 2-chambered, compressible pouch system. Three methods of electrical stimulation were used: (a) continuous 2 sec-1 single pulses that caused muscle twitching, (b) a 250 msec train of pulses (36 sec-1) that caused tetanic muscle contractions and was repeated every 2 sec for 15 min followed by a 15 min period of rest, and (c) alternating 15 min periods of the above 2 stimulation methods to cause alternating twitch and tetanic contractions. The 2 sec-1 twitch stimulation and the combined twitch/tetanic stimulation methods resulted in a 100% conversion to fatigue-resistant fibers within 6 weeks. Standardized muscle function tests were performed weekly. With the twitch stimulation (Method 1), the time to fatigue increased from 9 to 116 min (p less than 0.001), but fluid pumping ability of the muscle decreased substantially from 0.25 to 0.14 liters min-1 (p less than 0.05). With the intermittent tetanic stimulation (Method 2), the fatigue resistance increased only slightly from 7 to 11 minutes (p = NS), and pumping ability was unchanged. With the combined (twitch-tetanic) stimulation (Method 3), the time to fatigue increased from 9 to 107 min (p less than 0.001), and the pumping ability did not significantly change from 0.20 to 0.22 liters min-1 (p = NS). These results suggest that a combined electrical stimulation method which produces both twitches and tetanic contractions can achieve rapid fiber conversion and increased fatigue resistance without loss of muscle strength Bajuk S., Jelnikar T., and Ortar M. (1996) Rehabilitation of patient with brachial plexus lesion and break in axillary artery. Case study. Abstract: This paper describes the physiotherapy and occupational therapy used in treating a 74-year-old woman with a left brachial plexus lesion, a break in the axillary artery, dislocation of the acromioclavicular joint, a broken scapula and clavicula, serial left rib fractures, and lacerations on the upper and lower arm. After testing the patient, the following goals were set: reduce pain, soften scar tissue, and improve joint motion, muscle strength, and functionality of the hand. A 12-month outpatient program was used. …