THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. It may arise not only because of peripheral changes at the level of the muscle, but also because the central nervous system fails to drive the motoneurons adequately. Evidence for “central” fatigue and the neural mechanisms underlying it are reviewed, together with its terminology and the methods used to reveal it. Much data suggest that voluntary activation of human motoneurons and muscle fibers is suboptimal and thus maximal voluntary force is commonly less than true maximal force. Hence, maximal voluntary strength can often be below true maximal muscle force. The technique of twitch interpolation has helped to reveal the changes in drive to motoneurons during fatigue. Voluntary activation usually diminishes during maximal voluntary isometric tasks, that is central fatigue develops, and motor unit firing rates decline. Transcranial magnetic stimulation over the motor cortex during fatiguing exercise has revealed focal cha...

Spinal and Supraspinal Factors in Human Muscle Fatigue

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Chapter 4. European guidelines for the management of chronic nonspecific low back pain.

: This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency metric, and a classifier independent saliency metric are developed and tested. Ruck's saliency metric, the decision boundary based saliency metric, and the classifier independent saliency metric are compared for a data set consisting of the RSI and Stochastics indicators as well as delayed closing price values. The decision based metric and the Ruck metric results are similar, but the classifier independent metric agrees with neither of the other metrics. The nine most salient features, determined by the decision boundary based metric, are used to train a neural network and the results are presented and compared to other published results. (AN)

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Nonlinear Time Series Analysis.

1. Introduction 2. Concepts, theories and models, and types of measurements 3. The development of a measurement instrument 4. Field testing - item reduction and data structure 5. Reliability 6. Validity 7. Responsiveness 8. Interpretation 9. Systematic reviews of measurement properties Index.

Measurement in Medicine: A Practical Guide

Endurance time of back muscle in relation to external load

This paper presents recent developments on effects of rest and fatigue loading on properties of healthy vertebra discs. A comparison of different approaches used in literature to study the properties of intervertebral disc is presented. The major achievements in this area so far are discussed in the context of their advantages and disadvantages. The past approaches are based on bio-mechanical models which mostly used statistical techniques for the analysis and estimation of fatigue loaded Intervertebral Disc (IVD). However, those modeling techniques were not flexible enough for analysis of customized tests. In this paper, we applied System Identification (SI) based NLARX modeling technique for capturing the dynamics of system for the analysis of fatigue loaded IVD and also to identify the changes in system parameters with time. Simulation results show that a good accuracy is achieved in estimation for different test conditions.

Fatigue Loaded Intervertebral Disc Analysis for Low Back Pain Using Nonlinear Black-Box Model

Neurons in area PEc, a visual area located in the superior parietal lobule, are activated by optic flow stimuli. An important issue is whether PEc neurons are able to integrate multimodal signals, such as those related to optic flow selectivity with those about eye and head position. The aim of this study was to assess if angle of gaze and/or head rotation modify the spatial representation of the focus of expansion (FOE), varying FOE, fixation point and head position in space. We found that the rotation of head modulated the firing activity of PEc optic flow neurons. The head position also changed the angle of gaze effect on the PEc neuronal activity. All recorded neurons showed a main interaction effect between head and eye position upon the selectivity for optic flow stimuli. These results seem to suggest that PEc optic flow neurons use different reference frames depending on the position of the eye and/or the head in space emphasizing a possible contribution of this area in guiding locomotion by integrating multiple extraretinal inputs. 

Assessment of the lumbar muscle co-contraction in trunk flexion and bending movements at different velocities, using time-varying muscle synergies

BACKGROUND
Unloading knee orthosis is prescribed for people with unicompartmental knee osteoarthritis (OA) to unload the damaged compartment. However, despite its benefits, wearing unloading knee orthoses in the long term may decrease knee muscle activity and have a side effect on knee OA progression rate.


OBJECTIVES
Therefore, this study aimed to determine whether equipping an unloading knee orthosis with local muscle vibrators improves its effectiveness in improving clinical parameters, medial contact force (MCF), and muscular activation levels.


METHODS
The authors performed a clinical evaluation on 14 participants (7 participants wearing vibratory unloading knee orthoses and 7 participants wearing conventional unloading knee orthoses) with medial knee OA.


RESULTS
Wearing both orthoses (vibratory and conventional) for 6 weeks significantly improved (p < 0.05) the MCF, pain, symptoms, function, and quality of life compared with the baseline assessment. Compared with the baseline assessment, the vastus lateralis muscle activation level significantly increased (p = 0.043) in the vibratory unloading knee orthoses group. The vibratory unloading knee orthoses significantly improved the second peak MCF, vastus medialis activation level, pain, and function compared with conventional unloading knee orthoses (p < 0.05).


CONCLUSIONS
Given the potential role of medial compartment loading in the medial knee OA progression rate, both types of unloading knee orthoses (vibratory and conventional) have a potential role in the conservative management of medial knee OA. However, equipping the unloading knee orthoses with local muscle vibrators can improve its effectiveness for clinical and biomechanical parameters and prevent the side effects of its long-term use.

Evaluating the effect of equipping an unloading knee orthosis with local muscle vibrators on clinical parameters, muscular activation level, and medial contact force in patients with medial knee osteoarthritis: A randomized trial.

Graphical abstract Recent studies show that asymmetric movements are important Low Back Disorders risk factors. Measuring the trunk strength and identifying the coupling effects in different postures can provide an objective tool to assess one’s task capacity. This paper estimates the maximum performance capacity for isometric trunk extension and accompanying torques. Thirty males performed maximum voluntary isometric extension in 33 trunk postures on Sharif Lumbar Isometric Strength Tester device. Corresponding moments and angular positions were collected. Second-order full response surface models (RSM) were exploited to formulate the relationship between strengths and three trunk angles. The results of correlation coefficient, percent of standard estimation error and lack of fit reflected the adequacy of models. In conclusion, the main torque was the extension, but at the same time lateral bending and rotation torques were observed. For predicting these three torques in a specific posture and injury prevention, the second order RSM is a useful tool. The presented models can be used in the fields of ergonomics, occupational biomechanics and sport.

Mohamad Parnianpour

Papers

Endurance time of back muscle in relation to external load

Fatigue Loaded Intervertebral Disc Analysis for Low Back Pain Using Nonlinear Black-Box Model

Assessment of the lumbar muscle co-contraction in trunk flexion and bending movements at different velocities, using time-varying muscle synergies

Evaluating the effect of equipping an unloading knee orthosis with local muscle vibrators on clinical parameters, muscular activation level, and medial contact force in patients with medial knee osteoarthritis: A randomized trial.

Normative database of response surface method for human trunk extension in isometric mode