Thesis (M. Phil.)--University of Hong Kong, 1991.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: CMRR; Equalization filter; noise deduction. Includes bibliographical references (p. 64-66).

Vibration stimulation has been used as a tool to relieve muscle pain and spasm in physical therapy for many years. However recently, vibration, mainly Whole Body Vibration (WBV), has been increasingly studied and used as an exercise intervention in sports and rehabilitation. Although the physiological mechanisms which guide the body's response to this exercise modality are relatively poorly understood, evidence indicates that vibration can enhance muscle strength, power, and flexibility as well as increase bone mineral density in the general population. Evidence also suggests that the neuromuscular response to vibration stimulation depends on muscle length, stretch level (contraction) along with the vibration characteristics. One way to alter muscle length and contraction levels while receiving vibration is to superimpose the stimulation on graded isometric contraction. However, current WBV device designs cannot facilitate the delivery of vibration stimulation superimposed on graded isometric voluntary contraction. The aim of this PhD project was twofold, firstly to develop and evaluate a prototype WBV device which enables the delivery of vibration stimulation that can be superimposed on graded isometric contraction and secondly, to assess the neuromuscular responses to vibration superimposed on graded isometric contractions in lower limbs using this device. Due to the novelty of the device design and the method of the delivery, this study initially investigated the effects of different vibration frequencies and amplitudes combined with various effort levels on neuromuscular responses in lower limbs. The results of this study confirm that isometric contraction superimposed on vibration stimulation induce enhanced neuromuscular activity in the lower limbs. The results also confirm that although the neuromuscular responses to vibration depend on multiple factors the main determinants seem to be the vibration frequency, amplitude and muscle contraction /forc The results also confirm that although the neuromuscular responses to vibration depend on multiple factors the main determinants seem to be the vibration frequency, amplitude and muscle contraction /force level. Another limitation of most existing vibration devices is that they are not capable of delivering frequency of the vibration independent of amplitude and vice versa. Further, the evidence suggests that vibration amplitude can play an important role in neuromuscular response to vibration, especially when superimposed with graded contraction/force levels. To address the above limitation, the second aim of this PhD project was to develop and evaluate a prototype miniature upper limb vibration device capable of delivering precise and independent vibration frequency and amplitude stimulation. The miniature upper limb vibration (ULV) device with piezo actuators developed for this thesis, enables precise vibration stimulation to be delivered in a seated position with graded voluntary contraction superimposed. The neuromuscular responses to vibration superimposed on graded isometric contractions in upper limbs were also assessed by investigating the fatiguing effects of superimposed vibration stimulation using this newly developed device. This study is the first to investigate and compare the fatiguing effects of superimposed vibration stimulation pre and postvibration exercise in upper limbs. The results of this study confirm that isometric contraction superimposed on vibration stimulation lead to increased fatigue levels and neuromuscular activity in upper limbs. The results also indicate that post-vibration treatment the muscles display enhanced force generation capability associated with lower fatigue levels. In summary, two (WBV and ULV) novel vibration exercise devices were successfully developed and evaluated for this thesis. The results of the studies on these devices confirm that vibration stimulation superimposed on graded isometric contraction can induce higher neuromuscular activity compared to isometric contraction alone in both upper and lower limbs. However the effects of vibration frequency, amplitude and contraction/force levels seem to differ between the upper and lower limbs.

Smooth muscles as a group exhibit great diversity of pharmacological and physiological properties. This makes it impossible to produce any but extremely generalised schemes for smooth muscle contractile mechanisms. However, knowledge of the detailed physiology and pharmacology of specific types of smooth muscle has been growing at an increasing rate, especially regarding vascular and visceral muscles. The rat anococcygeus muscle has, however, been investigated little. This work describes the excitation- contraction coupling mechanism in this preparation. The rat anococcygeus muscle was found to contract to all three of the agonists used (noradrenaline, acetylcholine and potassium chloride). In the first section of this work the properties of these contractions were investigated. It was found that the contractions induced by each agonist exhibited different pharmacological properties, (with regard to low calcium, sodium nitroprusside, verapamil, Stellazine and theophylline). This can be taken as an indication that the different agonists use different activation pathways. Electrophysiological studies showed that the membrane potential per se is not important in the regulation of contraction. (ie. the depolarisation produced by an agonist is not simply related to the tension produced ). KC1 produces the greatest change in membrane potential (from -55mV to -20mV for a maximal dose), but produces the least rise in tension of the three agonists. Evidence from other preparations and the results of the experiments with Stellazine suggest that the rise in tension produced by the agonists is not simply related to the rise in intracellular calcium concentration, but that some amplification of the response occurs. The way in which the agonists produce this amplification of the response is suggested as being related to changes in the levels of the cyclic nucleotides, cAMP and cGMP within the cells. It was found that the agonists did not substantially affect cAMP levels, but that all three reduced cGMP levels by varying amounts. The ratio of the levels of cAMP/cGMP produced by activation with each agonist correllates very well with the tension produced. This suggests that the ratio cAMP/cGMP is important in the regulation of contractility in this muscle. However, doubt is cast upon this theory by the results of experiments using sodium nitroprusside (NP). It was found that NP (2 X 10-7M) caused a pronounced change in the ratio cAMP/cGMP (by increasing cGMP levels ), but only a small change in tension (so that the tension in these experiments does not correllate well with the ratio cAMP/cGMP). In order to retain the hypothesis that cyclic nucleotides are important in the regulation of contractility in this preparation, it is proposed that some form of compartmentalisation of the cyclic nucleotide changes occurs within the cells.

It is in the best interests of sportsmen and sportswomen to try to avoid muscle stiffness and soreness. Apart from the discomfort experienced, muscle stiffness and soreness can cause unnecessary interruptions to training, may lead to injury and will reduce performance. Changes in muscle tone were quantified in terms of the Resonant Frequency (squared) (RF2) and the Amplitude of Movement (AM) in response to an applied torque. Muscle soreness was measured at twelve sites on the arm. Study One investigated the effects of a single bout of eccentric exercise on muscle stiffness and muscle soreness. RF2 increased and AM decreased following exercise and reached a maximum and minimum, respectively, 24-48 hours post exercise (p < 0.01). Muscle soreness also reached a peak 24-48 hours post-exercise (p < 0.01). Greatest soreness was in the biceps brachii and in the proximal ends of the brachioradialis and the flexor carpi radialis (p < 0.01). Voluntary extension was more painful than voluntary flexion following eccentric exercise. Study Two investigated the effect of performing two subsequent exercise bouts (EX1 and EX2), each separated by six days and an adaptation was observed. Each of the variables measured (RF2, AM, Soreness, Creatine Kinase, Limb Girth) showed a reduced response following EX2 when compared to the results of EX1 (p < 0.01). The resting angle of elbow flexion appeared to decrease following exercise. Study Three investigated the effect of muscle soreness on motor performance. The ability to perform a simple perception test was not affected while suffering from muscle soreness. The eccentric exercise is thought to cause damage to the connective tissue and muscle cell membrane leading to a build-up of fluid around the joint. This increased edema may explain the increase in muscle stiffness observed. Further research is required to determine whether changes in muscle tone are also observed following isometric and concentric exercise.

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by Lanyi Xu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. [175]-186). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Thesis (M.S.)--University of Michigan, 1982.