Relaxation Protocol Research Articles

Constitutive equations for ligament and other soft tissue: evaluation by experiment

Ligaments, tendons and other soft tissues are nonlinearly viscoelastic. To discriminate among various constitutive equations which may be used to describe the tissue, appropriate experimental modalities are requisite. Ideally, testing should span physiologic ranges for load (or strain), load history (recovery and reloading), and load onset and duration, and a robust model will fit all data. Methods to expand the experimental window of time for relaxation and creep are presented and evaluated. The role of ramp, relaxation and recovery protocols is studied in the context of viscoelasticity describable by linear, quasi-linear, nonlinear superposition, Schapery, and multiple integral formulations. The advantages associated with testing protocols that expand the time windows for creep or relaxation are presented.

Energy-efficient relaxed rekeying policies for distributed key management in sensor networks

In this paper, we discuss a basic key management protocol to generate and distribute the keys required for a secure group communication system, which also preserves the backward and forward secrecies. We devise a few relaxed policies for rekeying and formulate an enhanced set of protocols for key management. All the communications in the protocols are properly authenticated using Elliptic Curve Digital Signature scheme. The relaxed protocols reduce the number of rekeying to almost 25%, thus saving energy. The security analysis shows that our protocols can withstand several possible security attacks especially the serious one, the node capture attack.

Athlete compliance to therapist requested contraction intensity during proprioceptive neuromuscular facilitation

Contraction intensities between 10 and 100% maximal voluntary contraction (MVC) have been proposed in varying muscle energy technique (MET) and proprioceptive neuromuscular facilitation (PNF) post-isometric relaxation (PIR) protocols. The current study was undertaken to determine if athletes were able to comply with differing therapist requested contraction intensities during (PNF) stretching protocols. Thirty-six university athletes were recruited and MVC was established at hip extension, hip adduction, and horizontal shoulder adduction. Target PIR contractions were set at 20, 50 and 100% MVC and monitored throughout the contractions with a strain gauge dynamometer. Athletes were not able to match the target contraction values at 20 and 100% MVC ( P ≤ 0.001). When examined for consistency across the three component contractions within each of the three PIR protocols, the athletes demonstrated widely variable scores (coefficient of variation (CV) = 23.2–36.4% at 20% MVC; CV = 19.3–29.4% at 50% MVC; and, CV = 9.4–14.5% at 100% MVC). Our findings indicate that this group of athletes displayed a poor level of compliance to varying therapist requested contraction intensities with respect to both accuracy and consistency.

Relaxation as treatment for chronic musculoskeletal pain – a systematic review of randomised controlled studies

Objectives: To review studies on relaxation treatment for chronic musculoskeletal pain.Methods: Searches in the databases PubMed, PEDro, CINAHL, Amed, the electronic library information navigator (ELIN), and the British Medical Journal and Science Direct, found 12 relevant studies. Inclusion criteria were: randomised controlled trials (RCTs); studies including a total of at least 25 subjects at the end of intervention; relaxation techniques as single treatment, or combined with education, with the participants being active in the treatment.Results: A total of 12 studies fulfilled all inclusion criteria and were reviewed. Quality assessment showed that all studies were of medium quality. The relaxation techniques used were: progressive muscle relaxation ad modum Jacobson (most common), autogenic training ad modum Schultz, hypnosis, guided imagery and biofeedback. Positive effects were found regarding decreases in pain intensity, anxiety, depression, and fatigue (in fibromyalgia). Even decreases in medication and health costs were seen. Increased mobility and use of coping strategies were also reported.Conclusion: Relaxation training could be effective for patients with chronic musculoskeletal pain. The experimental study designs need to be of improved scientific quality and should, for example, include clear self-training relaxation protocols and suitable control groups. RCTs of high quality are necessary.

EFFECT OF MECHANOMYOGRAPHY AS A BIOFEEDBACK METHOD TO ENHANCE MUSCLE RELAXATION AND PERFORMANCE

The purpose of the study was to examine the potential for using the mechanomyographic (MMG) signal as a biofeedback method to enhance muscular relaxation and to improve performance during forearm flexion repetitions to fatigue. Twelve adult (mean +/- SD; age: 22.0 +/- 1.1 years) moderately trained subjects (weight: 82.3 +/- 29.2 kg; height: 165.7 +/- 49.0 cm) were instructed to relax the biceps brachii muscle using MMG biofeedback (BIO) provided by viewing a computer screen graphically displaying the MMG signal and then without using MMG biofeedback (NOBIO). Electromyographic (EMG) and MMG signals were detected midway over the biceps brachii during the relaxation protocol. In subsequent visits to the laboratory, subjects performed as many repetitions as possible at 85% of 1 repetition maximum with BIO and NOBIO using the seated preacher curl exercise. Two-way (biofeedback x gender) mixed factorial analyses of variance revealed significantly (p < 0.05) lower MMG (mean +/- SEM; BIO = 0.6 +/- 0.1 mV; NOBIO = 1.1 +/- 0.2 mV) and EMG amplitudes (BIO = 6.6 +/- 0.6 microV; NOBIO = 9.4 +/- 1.4 microV) for BIO when subjects were instructed to relax the biceps brachii muscle. There was no significant difference in the number of forearm flexion repetitions performed for BIO (mean +/- SD; 7.9 +/- 0.4 reps) vs. NOBIO (8.1 +/- 0.6 reps). The results of the present study revealed that using MMG as a biofeedback technique can enhance the development of muscle relaxation, but is not useful in delaying fatigue during forearm flexion repetitions. Our results may have been influenced by a relatively short training phase designed to teach subjects to use the MMG signal as a biofeedback method. Future studies are needed to determine whether MMG biofeedback can be used for other purposes. If MMG is found to be useful as a biofeedback method, it has some distinct practical advantages over EMG that the strength and conditioning athlete and professional may find appealing.

Connecting nitrogenase intermediates with the kinetic scheme for N 2 reduction by a relaxation protocol and identification of the N 2 binding state

A major obstacle to understanding the reduction of N2 to NH3 by nitrogenase has been the impossibility of synchronizing electron delivery to the MoFe protein for generation of specific enzymatic intermediates. When an intermediate is trapped without synchronous electron delivery, the number of electrons, n, it has accumulated is unknown. Consequently, the intermediate is untethered from kinetic schemes for reduction, which are indexed by n. We show that a trapped intermediate itself provides a "synchronously prepared" initial state, and its relaxation to the resting state at 253 K, conditions that prevent electron delivery to MoFe protein, can be analyzed to reveal n and the nature of the relaxation reactions. The approach is applied to the "H+/H- intermediate" (A) that appears during turnover both in the presence and absence of N2 substrate. A exhibits an S = 1/2 EPR signal from the active-site iron-molybdenum cofactor (FeMo-co) to which are bound at least two hydrides/protons. A undergoes two-step relaxation to the resting state (C): A --> B --> C, where B has an S = 3/2 FeMo-co. Both steps show large solvent kinetic isotope effects: KIE approximately 3-4 (85% D2O). In the context of the Lowe-Thorneley kinetic scheme for N2 reduction, these results provide powerful evidence that H2 is formed in both relaxation steps, that A is the catalytically central state that is activated for N2 binding by the accumulation of n = 4 electrons, and that B has accumulated n = 2 electrons.

Protein structure prediction by all-atom free-energy refinement

BackgroundThe reliable prediction of protein tertiary structure from the amino acid sequence remains challenging even for small proteins. We have developed an all-atom free-energy protein forcefield (PFF01) that we could use to fold several small proteins from completely extended conformations. Because the computational cost of de-novo folding studies rises steeply with system size, this approach is unsuitable for structure prediction purposes. We therefore investigate here a low-cost free-energy relaxation protocol for protein structure prediction that combines heuristic methods for model generation with all-atom free-energy relaxation in PFF01.ResultsWe use PFF01 to rank and cluster the conformations for 32 proteins generated by ROSETTA. For 22/10 high-quality/low quality decoy sets we select near-native conformations with an average Cα root mean square deviation of 3.03 Å/6.04 Å. The protocol incorporates an inherent reliability indicator that succeeds for 78% of the decoy sets. In over 90% of these cases near-native conformations are selected from the decoy set. This success rate is rationalized by the quality of the decoys and the selectivity of the PFF01 forcefield, which ranks near-native conformations an average 3.06 standard deviations below that of the relaxed decoys (Z-score).ConclusionAll-atom free-energy relaxation with PFF01 emerges as a powerful low-cost approach toward generic de-novo protein structure prediction. The approach can be applied to large all-atom decoy sets of any origin and requires no preexisting structural information to identify the native conformation. The study provides evidence that a large class of proteins may be foldable by PFF01.

NMR relaxation study of avocado quality

Four nuclear magnetic resonance relaxation protocols are investigated as potential candidates for off-line and on-line determination of avocado maturity. Two-dimensionalT1-T2 andT2-D correlation spectroscopy provides the most information but is only suitable for off-line quality control. The CPMGT2 spectrum gives avocado oil content but requires intensive data processing. Suppression of the tissue water signal byT1-Null methods is shown to be unreliable but a new, single-shot pulse sequence which uses diffusive attenuation to suppress the tissue water is shown to give a good correlation with oil content and is suitable for both off-line and on-line implementation.

The Effect Of Mechanography As A Biofeedback Mechanism For Muscle Relaxation And Performance

Mechanomyography (MMG) is the recording of muscular vibrations that has been shown to be helpful in providing biofeedback to subjects when attempting to control an external prosthesis (Barry et al., Arch Phys Med Rehabil 67:267–269, 1986). No previous studies however, have determined whether MMG can be utilized to provide information to subjects on their muscle function that will allow for enhanced muscular relaxation and/or performance. PURPOSE The purpose of the present study was to examine the MMG signal as a biofeedback mechanism during muscular relaxation and with isotonic repetitions to fatigue. METHODS On two separate occasions twelve adult (mean±SD; age=22.0±1.1 yrs) subjects (weight=82.3±29.2 kg; height=165.7±49.0 cm) were instructed to relax their biceps brachii muscle as much as possible while being provided with (by viewing a computer screen graphically displaying the MMG signal) MMG biofeedback (BIO) and then without MMG biofeedback (NOBIO). EMG and MMG were detected midway over the biceps brachii during testing. Following the relaxation protocol, subjects performed as many repetitions as possible at 85% of their 1-RM with BIO and NOBIO using the seated preacher curl bar. RESULTS Paired t-tests revealed significantly (p<0.05) lower MMG amplitude (mean±SEM; BIO=0.6±0.1 mV; NOBIO=1.1±0.2 mV) but no significant difference in EMG amplitude (BIO=6.6±0.7 μ NOBIO=10.4±2.4 μ) for BIO when subjects were instructed to relax their muscle. There was no significant difference in the number of forearm flexion repetitions performed for BIO (mean±SD=7.9±0.4 reps) versus NOBIO (8.1±0.6 reps). CONCLUSION The results of the present study revealed that using MMG as a biofeedback technique can enhance the development of muscle relaxation but was not useful when performing forearm flexion repetitions to fatigue. Future studies are necessary to determine if MMG can be used for other purposes (ie., pain control, improved athletic performance for other activities, diagnosis of muscle diseases) that may be sensitive to biofeedback.

Fixed and pulsed gradient diffusion methods in low-field core analysis

We review diffusion-weighted relaxation protocols for two-dimensional diffusion/relaxation time (D, T(2)) distributions and their application to fluid-saturated sedimentary rocks at low fields typical of oil-well logging tools (< or = 2 MHz for 1H). Fixed field gradient (FFG) protocols may be implemented in logging tools and in the laboratory; there, pulsed field gradient (PFG) protocols are also available. In either category, direct or stimulated echoes may be used for the diffusion evolution periods. We compare the results of several variant FFG and PFG protocols obtained on liquids and two contrasting sedimentary rocks. For liquids and rocks of negligible internal gradients (g(int)), results are comparable, as expected, for all the studied protocols. For rocks of strong g(int), protocol-dependent artifacts are seen in the joint (D, T2) distributions, consistent with the effects of the internal fields. For laboratory petrophysics, the PFG methods offer several advantages: (a) significantly improved signal-to-noise ratio and acquisition times for repetitions over many samples; (b) freedom from heteronuclear contamination when fluorinated liquids are used in core holders; and (c) a palette of variants--one comparable with the FFG--for the study of rocks of significant g(int). Given suitable hardware, both PFG and FFG methods can be implemented in the same bench-top apparatus, providing a versatile test bed for application in a petrophysical laboratory.

Effects of static flexion–relaxation on paraspinal reflex behavior

Background. Static trunk flexion working postures and disturbed trunk muscle reflexes are related to increased risk of low-back pain. Animal studies conclude that these factors may be related; passive tissue strain in spinal ligaments causes subsequent short-term changes in reflex. Although studies have documented changes in the myoelectric onset angle of flexion–relaxation following prolonged static flexion and cyclic flexion we could find no published evidence related to the human reflex response of the trunk extensor muscles following a period of static flexion–relaxation loading. Methods. Eighteen subjects maintained static lumbar flexion for 15 min. Paraspinal muscle reflexes were elicited both before and after the flexion–relaxation protocol using pseudorandom stochastic force disturbances while recording EMG. Reflex gain was computed from the peak value of the impulse response function relating input force perturbation to EMG response using time-domain deconvolution analyses. Findings. Reflexes showed a trend toward increased gain after the period of flexion–relaxation ( P < 0.055) and were increased with trunk extension exertion ( P < 0.021). Significant gender differences in reflex gain were observed ( P < 0.01). Interpretations. Occupational activities requiring extended periods of trunk flexion contribute to changes in reflex behavior of the paraspinal muscles. Results suggest potential mechanisms by which flexed posture work may contribute to low-back pain. Significant gender differences indicate risk analyses should consider personal factors when considering neuromuscular behavior.

An interaction of coherence protocols and memory consistency models in DSM systems

Coherence protocols and memory consistency models are two improtant issues in hardware coherent shared memory multiprocessors and softare distributed shared memory(DSM) systems. Over the years, many researchers have made extensive study on these two issues repectively. However, the interaction between them has not been studied in the literature. In this paper, we study the coherence protocols and memory consistency models used by hardware and software DSM systems in detail. Based on our analysis, we draw a general definition for memory consistency model, i.e., memory consistency model is the logical sum of the ordering of events in each processor and coherence protocol. We also point that in hardware DSM system the emphasis of memory consistency model is relaxing the restriction of event ordering, while in software DSM system, memory consistency model focuses mainly on relaxing coherence protocol. Taking Lazy Release Consistency(LRC) as an example, we analyze the relationship between coherence protocols and memory consistency models in software DSM systems, and find that whether the advantages of LRC can be exploited or not depends greatly on it's corresponding protocol. We draw the conclusion that the more relaxed consistency model is, the more relaxed coherence protocol needed to support it. This conclusion is very useful when we design a new consistency model. Furthermore, we make some improvements on traditional multiple writer protocol, and as far as we aware, we describe the complex state transition for multiple writer protocol for the first time. In the end, we list the main research directions for memory consistency models in hardware and software DSM systems.

Relaxed consistency and coherence granularity in DSM systems

During the past few years, two main approaches have been taken to improve the performance of software shared memory implementations: relaxing consistency models and providing fine-grained access control. Their performance tradeoffs, however, we not well understood. This paper studies these tradeoffs on a platform that provides access control in hardware but runs coherence protocols in software, We compare the performance of three protocols across four coherence granularities, using 12 applications on a 16-node cluster of workstations. Our results show that no single combination of protocol and granularity performs best for all the applications. The combination of a sequentially consistent (SC) protocol and fine granularity works well with 7 of the 12 applications. The combination of a multiple-writer, home-based lazy release consistency (HLRC) protocol and page granularity works well with 8 out of the 12 applications. For applications that suffer performance losses in moving to coarser granularity under sequential consistency, the performance can usually be regained quite effectively using relaxed protocols, particularly HLRC. We also find that the HLRC protocol performs substantially better than a single-writer lazy release consistent (SW-LRC) protocol at coase granularity for many irregular applications. For our applications and platform, when we use the original versions of the applications ported directly from hardware-coherent shared memory, we find that the SC protocol with 256-byte granularity performs best on average. However, when the best versions of the applications are compared, the balance shifts in favor of HLRC at page granularity.

Cardiorespiratory Responses to Intermittent Exercise and Relaxation as Compared with Continuous Exercise

Cardiorespiratory responses to intermittent exercise and relaxation were comparable to cardiorespiratory responses to continuous exercise. The time of workout and work loads were kept constant in both protocols. Even though in the intermittent exercise and relaxation protocol the 10 subjects rested nearly two-thirds of the duration of the workout, cardiorespiratory responses were similar to those which the same subjects attained while exercising continuously throughout the entire steady state workout at approximately 64% maximal heart rate.

Efficacy of a Computer-Assisted Voice Treatment Protocol

A voice treatment protocol using a computer-assisted biofeedback device for hyper-functional voice disorders was evaluated in two adults. The specific components of the treatment were assessed using a single-subject interaction design. The overall contribution of relaxation to the treatment package was also evaluated. The treatment package was effective in improving the voice, as demonstrated by elimination of the vocal nodules, subjective data (ratings of the voice by subjects and naive listeners), and objective data (changes in fundamental frequency, maximum phonation time, perturbation factor percentages, breathing errors, and slow rise in volume). It appeared that the effect of the combined relaxation and traditional voice protocol was cumulative in nature, and addition of therelaxation component was no more effective than the protocol without the relaxation component.

Controlled evaluation of the addition of cognitive strategies to a home-based relaxation protocol for tension headache

Chronic tension headache sufferers were randomized in the approximate ratio of 2:2:1 to one of three regimens: (1) progressive muscle relaxation (PMR) training delivered as a largely home-based treatment; (2) PMR plus selected cognitive stress coping techniques, again delivered as a largely home-based treatment; or (3) a headache monitoring, wait-list control condition. All patients monitored headaches daily for at least 4 weeks before and after treatment. In general, the two active treatment groups were significantly improved relative to the wait-list control group on measures of reduction in headache activity and reduction in headache medication, derived from a daily headache diary, and on measures of clinically significant improvement. The two active treatment groups did not differ from each other on any measure. Thus, it appears that the addition of limited cognitive stress-coping techniques to PMR did not add significantly to treatment outcome utilizing the protocol described.

Cognitive imagery and physiological feedback relaxation protocols applied to clinically tense young adults: a comparison of state, trait, and physiological effects.

Examined changes in targeted and general tension behaviors as well as reductions in physiological tension associated with cognitive imagery and electromyographic biofeedback relaxation procedures. Three groups of 15 female college students participated. During three weekly sessions each person received either guided cognitive imagery relaxation, frontalis muscle feedback relaxation, or a self-rest control procedure. The Anxiety Differential was administered before and after each session, while frontalis EMG, heart rate, and skin temperature were monitored continuously. A second Temperament Analysis was administered after the final session. The imagery procedure was associated with moderate reductions in physiological tension and significant reductions in state anxiety and three tension-related personality dimensions. Self-rest persons displayed lesser reductions in general tension with little physiological change. While biofeedback persons showed the largest reductions in physiological tension, they displayed only small and variable changes in state anxiety and personality dimensions. The data raise continued questions about the application of physiologically based operant relaxation procedures and support the use of cognitively mediated protocols for the treatment of specific or general anxiety behaviors.

Living with long-term home dialysis.

Eleven of the 22 patients receiving home dialysis in the spring of 1973 from the dialysis unit of a university medical center hospital were interviewed to determine what factors might help or hinder patient adjustment to chronic renal failure alleviated by home dialysis. Two interviewers, following a relaxed protocol, talked with patients at home and recorded the interviews on tape and in notes. Four areas were identified in which well-adjusted patients differed significantly from those poorly adjusted: extent of change in physical or mental state due to disease, source and extent of financial support, role and relationship of helper to patient, and the importance that the patient perceived dialysis to have in his daily life. From the typical patients' profiles, some tentative suggestions to enhance patient adjustment are offered.