A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance

Pneumatic devices provide a resistance comprising minimal mass, possibly affording greater movement velocities, compared to free weight, while reducing the influence of momentum. Thirty men completed three testing sessions [free weight (FW), ballistic (BALL) and pneumatic (P)] each consisting of a one repetition maximum (1RM) and six sets (15, 30, 45, 60, 75 and 90% 1RM) of four explosive repetitions of a bench press. Dependent variables were expressed as mean and as a percentage of the concentric displacement. Significant differences (P < 0.05) were evaluated using two way repeated measures ANOVAs with Holm-Sidak post hoc comparisons. On average, the mean and peak P velocity were 36.5 and 28.3% higher than FW, and 22.9 and 19.1% higher than the BALL movements. The FW and BALL peak force were both significantly higher than the P (26.3 and 22.7% for FW and BALL, respectively). BALL mean power output was significantly higher than the FW and P at loads of 15 and 30% 1RM; however, between loads of 60-90% 1RM the highest mean power was produced with a P resistance. A 15% 1RM load maximized the peak power for each condition and no significant differences were found between the P and BALL. For loads of 45-90% 1RM the force, power and muscle activity were higher during the last 10-20% of the concentric displacement when subjects employed the P resistance. In summary, pneumatic resistance may offer specific advantages over loads comprising only mass (FW and BALL), although not without its own limitations.     

ATPase activity in the breast: a comparison between three methods.

Adenosine triphosphatase enzymatic activity was investigated in human approximatively normal, dysplastic and neoplastic mammary tissue, by three different methods. Staining intensity varied within wide limits; myoepithelial cells and blood vessels showed similar enzymatic activity. Epithelial cells reacted only faintly, or not at all; carcinoma cells were never labelled. Stromal response was highly variable. The calcium-cobalt method of Padykula and Herman gave more intense reactions than the lead-nitrate procedure of Wachstein and Meisel, either in the original form or according to the modifications recommended by Russo and Wells. With the latter method the sharpness of stain deposits on the different structures was markedly enhanced. The functional significance of ATPase activity is discussed.     

Learning to throw on a rotating carousel: recalibration based on limb dynamics and projectile kinematics

Skilled actions exhibit adjustment in calibration to bring about their goals. The sought-after calibrations change as a function of the environmental situation that stages the actions. In these experiments participants sat on one side of a rotating carousel and threw beanbags underhanded at a target fixed on the opposite side. Logically, aimed throwing in this situation involves adjustment to fit changes in limb dynamics (originating from Coriolis forces) and changes in perceived projectile kinematics (originating from the tangential velocity of thrower and target). We studied whether such adjustment involved one or multiple components of recalibration. An initial experiment showed that exposure to rotation while throwing beanbags produced a robust recalibration in the direction of underhanded throws as manifest in throwing at stationary targets from a stationary position. Following some initial decay this recalibration persisted and approached an asymptote. Subsequent experiments suggested two independent components of recalibration. One is based on limb dynamics and accounts for the initial decay. The other is based on the perceived projectile kinematics and accounts for the stable change in throwing direction. These results raised the question of how multiple components of recalibration of an action are related. We propose that movement components are independent and calibrated separately at different levels in the organization of an action.     

Parallels in control of voluntary and perturbation-evoked reach-to-grasp movements: EMG and kinematics

To determine the potential differences in control underlying compensatory and voluntary reach-to-grasp movements the current study compared the kinematic and electromyographic profiles associated with upper limb movement. Postural perturbations were delivered to evoke compensatory reach-to-grasp in ten healthy young adult volunteers while seated on a chair that tilted as an inverted pendulum in the frontal plane. Participants reached to grasp a laterally positioned stable handhold and pulled (or pushed) to return the chair to vertical. The distinguishing characteristic between the two behaviors was the onset latency and speed of movement. Consistent with compensatory balance reactions, the perturbation-evoked reach response was initiated very rapidly (137 vs. 239 ms for voluntary). As well the movement time was shorter, and peak velocity was greater for PERT movements. In spite of the profound differences in timing, the sequence of muscle activity onsets and the order of specific kinematic events were not different between maximum velocity voluntary (VOL) and perturbation-evoked (PERT) reach-to-grasp movements. Peak velocity and grasp aperture occurred prior to hand contact with the target for PERT and VOL movements, and wrist trajectory was influenced by the direction of perturbation relative to the target. To achieve such target specific control for responses initiated within 100 ms of the perturbation, and when characteristics of body movement were unpredictable, the perturbation-evoked movements would need to incorporate sensory cues associated with body movement relative to the target into the earliest aspects of the movement. This suggests reliance on an internal spatial map constructed prior to the onset of perturbation. Parallels in electromyographic and kinematic profiles between compensatory and voluntary reach-to-grasp movements, in spite of temporal differences, lead to the view they are controlled by common neural mechanisms.     

Effect of arm position on the prediction of kinematics from EMG in amputees

Myoelectric control has been extensively applied in multi-function hand/wrist prostheses. The performance of this type of control is however, influenced by several practical factors that still limit its clinical applicability. One of these factors is the change in arm posture during the daily use of prostheses. In this study, we investigate the effect of arm position on the performance of a simultaneous and proportional myoelectric control algorithm, both on trans-radial amputees and able-bodied subjects. The results showed that changing arm position adversely influences the performance of the algorithm for both subject groups, but that this influence is less pronounced in amputee subjects with respect to able-bodied subjects. Thus, the impact of arm posture on myoelectric control cannot be inferred from results on able-bodied subjects and should be directly investigated in amputee subjects.     

Estimation of the specific activity of radioiodinated gonadotrophins: comparison of three methods

We compared 3 methods for estimating the specific activity of radioiodinated gonadotrophins. Two of the methods (column recovery and isotopic dilution) gave similar results, while the third (autodisplacement) gave significantly higher estimations. In the autodisplacement method, B/T ratios, obtained when either labelled hormone alone, or labelled and unlabelled hormone, are added to the antibody, were compared as estimates of the mass of hormone iodinated. It is likely that immunologically unreactive impurities present in the labelled hormone solution invalidate such comparison.     

Killing machines: three pore-forming proteins of the immune system

Immunologic Research - The evolution of early multicellular eukaryotes 400–500 million years ago required a defensive strategy against microbial invasion. Pore-forming proteins containing the...     

The effects of EMG biofeedback and relaxation training on primary dysmenorrhea

Fifteen dysmenorrhea sufferers received relaxation training with EMG biofeedback, relaxation training with no feedback, or no treatment. Participants who received biofeedback training did not differ from participants who received relaxation training in their ability to maintain a reduced level of EMG activity prior to the onset of menstruation. On the first day of menstruation, those receiving biofeedback training were able to maintain reduced EMG activity, whereas those receiving relaxation training showed an elevated level of EMG activity. Subjective reports indicated that the symptoms of dysmenorrhea improved for the biofeedback group during training but did not improve for the relaxation or control groups. Suggestions for further research are noted.The authors wish to thank Jerry Curtis for his invaluable assistance in setting up and maintaining the laboratory facilities and computer programs used to conduct this study.     

Comparison of EMG activity of medial and lateral hamstrings during isometric contractions at various cuff weight loads

Since both the medial head (MH) and lateral head (LH) of the hamstring muscles contribute to knee flexion, this study investigated whether the relative electrical activity of these heads remained constant with respect to each other or changed during isometric contractions at five different resistance levels. The relative electrical activity of these two heads was determined by comparing their integrated EMG (iEMG). Forty-two volunteers with no history of right lower extremity injury or disease, between the ages of 18 and 35, were studied. Following motor point location, surface electrodes were placed over the MH and LH. Subjects, positioned prone, flexed the knee to 45 degrees using a sawhorse as a tactile cue to help maintain this position. Three recordings, 8 s in length, were taken at each subject's maximum isometric contraction and then using cuff weights of 1, 3, 5, and 7% of their body weight. The average of the three recordings was used in the analysis. During maximum isometric contraction (at 45 degrees of knee flexion), the LH contributes a significantly greater percent of the total iEMG (63.4%) than the MH (P < 0.0001). Furthermore, within the four submaximal levels tested, the LH's contribution was significantly greater than the MH (P < 0.01). During submaximal isometric contractions, the LH percent contribution to total iEMG was less than its contribution during maximal isometric contraction, all P values < 0.005. As a result, during these same submaximal isometric contractions, the MH contribution to total iEMG was greater than its contribution during maximal isometric contraction, all P values < 0.005).     

基于斜床减重式下肢康复训练的人体关节受力分析

基于斜床减重式下肢康复训练,对人体下肢屈伸运动过程的关节进行运动与受力分析,将人体简化为7刚体模型,采用Lagrange方法进行动力学建模与分析,并在Matlab中对数学模型仿真,获得人体在斜床不同倾角下训练时关节所受力矩。关节力矩随着斜床倾角的增大而增大;随着人体大、小腿之间夹角的减小而增大。在ADAMS中根据人体参数建立几何模型进行仿真分析,计算两种模型结果间的相关系数,结果显示两种方法获得的关节力矩组间相关系数接近于1,验证了Lagrange方法建立的数学模型的合理性。本研究结果对制定个性化下肢康复训练方案提供良好的参考依据,并对下肢训练康复器械的开发具有指导意义。     

Measuring patient-centredness: a comparison of three observation-based instruments

The aim of this study was to assess the reliability and validity of three different observation-based measures of patient-centredness. The three face-valid instruments were each applied to the same sample of 55 videotaped GP consultations. Associations were explored with consultation 'input' variables (e.g. patient and doctor demographic characteristics, patient health status) and 'process' variables (e.g. consultation length). The three measures demonstrated varying levels of inter-rater reliability. Reliability was proportional to training requirements. Differences in construct validity of the three measures were evident and their concurrent validity was relatively low. Researchers must exercise caution in their choice of measurement method because of differences in how the concept of 'patient-centredness' is operationalized. Greater conceptual specificity and simplification are required for meaningful, reliable measurement. The implications for research, and for assessing the quality of individual doctors' 'interpersonal' care are discussed.     

Predicting differential response to EMG biofeedback and relaxation training: the role of cognitive structure

Analyzed treatment outcome data for 102 headache patients who had been assigned randomly to receive either EMG biofeedback (N = 70) or relaxation training (N = 32). It was hypothesized that a measure of cognitive structure would differentially predict success at the two training tasks and that patients high in cognitive structure would derive more benefit from the more structured relaxation task and less benefit from the biofeedback task. This hypothesis was confirmed (p less than .01). The analysis also demonstrated that relaxation training was significantly more effective than biofeedback (p less than .05) and that mixed headache patients improved significantly less (p less than .05) than either migraine or muscle-contraction headache patients.     

A comparison of EMG biofeedback and a credible pseudotherapy in treating tension headache

Thirty-one tension headache sufferers were assigned to frontalis electromyographic (EMG) biofeedback training, to a highly credible pseudotherapy providing no opportunity to learn control of EMG activity, or to a symptom-monitoring control group. Participants receiving biofeedback showed significant reductions in frontalis EMG within and across treatment sessions and exhibited reduced EMG activity following treatment. Participants receiving pseudotherapy showed no changes in EMG activity. Although biofeedback and pseudotherapy were rated as equally credible treatments, only the headache activity of the biofeedback group was significantly improved following treatment. These results suggest that outcomes obtained with biofeedback do not result merely from exposure to a credible treatment procedure. Evidence suggesting that headache improvements may be mediated by cognitive and behavioral changes and not the learned control of physiological activity is discussed.A grant from the Ohio University College of Osteopathic Medicine provided support for this research.     

Effect of congenital blindness on EMG activity of the facial muscles

The aim of this work was to analyze electromyographically the facial muscles: orbicularis oris (upper and lower fascicles), orbicularis oculi (right and left lateral portions) and frontal, in blind and clinically normal (control) individuals, in various clinical conditions. Electromyographic averages of all data collected were normalized by maximal voluntary contraction of the studied muscles and statistical analysis was performed by Student's t test, using "Statistical Package for the Social Sciences" software--SPSS 12.0 (Chicago, IL). It was found that electromyographic alterations occur in the facial musculature that influences facial expressions of individuals. Results for the orbicularis oris muscle demonstrated that myoelectric activity among blind and control subjects was greater for the control group at muscular rest, blowing, and in labial projection. Electromyographic analysis of the orbicularis oculi among blind and control subjects in three clinical conditions studied demonstrated that activity was greater for the control group at muscular rest, blinking, and forced blinking. For the frontal muscles were demonstrated that electromyographic activity was greater for blind individuals. These data suggest the influence of congenital blindness on muscular development, including alterations in electromyographic activity of skin musculature in individuals with visual impairment.     

Information versus experience: a comparison of an information leaflet on antidepressants with lay experience of treatment

The quality of patient information leaflets has been criticised for being too medico centred. Written information produced by a patient organisation should be tailored to members' expressed needs, and based on their experience and therefore useful in helping patients to self-manage their condition. Views expressed in semi-structured interviews with 30 members of a self help group for depression were compared with the content of an antidepressant leaflet produced by the parent organisation. The information leaflet used six frequently asked questions to deliver a biomedical discourse on antidepressants. Members of the group had questions not included in the leaflet around self help, stigma and sense of self, and more complex answers to the six questions. It cannot be assumed that information leaflets written by lay led organisations are patient centred and promote self help. To assist in facilitating concordance between patient and prescriber medicine information leaflets should draw on patient experience of the condition and treatment for it.     

Recording of foetal movements: a comparison of three methods

As decreased foetal movement (FM) may indicate impaired foetal health, FM recording has been suggested as a method of assessing foetal well-being. A non-intrusive, automated method of recording FM (FM-detector), was compared with maternal and ultrasonographic assessment of FMs in 24 women in the third trimester of pregnancy. The FM-detector detected a greater proportion of ultrasonographically recorded FMs than the mothers did (median 70% and 38%, respectively; p less than 0.001). Parity, gestational age, placental site or thickness, maternal weight or the distance from the maternal abdominal surface to the amniotic cavity did not affect the ability of the FM-detector to detect ultrasonographically recorded FMs. The estimation of FM strength by the FM-detector agreed fairly well with the assessment of FM strength by the ultrasound observer. The FM-detector would seem suitable for clinical use, as in the examination of pregnant women complaining of feeling 'less FM'.     

Analysis of maternal alpha-fetoprotein: a comparison of three radioimmunoassays

Increased levels of alpha-fetoprotein in maternal serum or amniotic fluid may be indicative of a fetal neural tube defect. The present investigation compares, prospectively and retrospectively, the analysis of serum or amniotic fluid alpha-fetoprotein from humans using three radioimmunoassays. A total of 46 sera and 137 prospective and 202 retrospective amniotic fluid samples collected at 12-26 weeks' gestation were assayed using our in-house Farr technique assay, a kit Farr technique assay, and a kit double-antibody assay. Analysis of quality control data in all three assays showed that within- and between-assay variations were less with the double-antibody technique. Additionally, the double-antibody assay offers the advantage of considerably lower nonspecific binding (1.7% vs 16-18% for the Farr technique assays). Of the 375 pregnancies sampled during this study, 340 (91%) resulted in normal singleton births, whereas three (1%) pregnancies were found to have elevated serum or amniotic fluid by all three assay methods and resulted in confirmed neural tube defects. Of the remaining, non-normal outcome without neural tube defect or elevated alpha-fetoprotein was determined in 27 (7%) pregnancies, and false-positive elevated alpha-fetoprotein levels were found for 5 (1%). Analysis of maternal alpha-fetoprotein by radioimmunoassay is a sensitive and accurate adjunct in the prenatal diagnosis of neural tube defects.     

力量训练和功能训练偏瘫阴性患者上肢神经肌肉功能的恢复：个案特点

背景：偏瘫患者上肢功能康复目前许多治疗方法,但针对患者的病症,以独立功能能力为目标的任务导向性训练方法报道不多。 目的：探讨功能训练和力量训练对偏瘫阴性特征患者上肢动作能力恢复的疗效。 方法：对因脑蛛网膜下腔出血,做动脉瘤栓塞时血管壁沉淀物堵塞中动脉血管造成右偏瘫致上运动神经元损伤的偏瘫阴性患者进行训练前后的BrunstormⅤ级动作测试,同时进行录像和肌电图测试,通过录像发现运动障碍,找出中枢性瘫痪肌肉,对患者瘫痪肌的功能进行运动学分析,治疗前后患侧神经肌肉功能的进步情况。 结果与结论：通过150次的训练,使患者完全失用的右手能完成功能训练(吃香蕉动作)14次。说明功能训练和力量训练对偏瘫阴性特征患者上肢动作能力的康复效果显著。