View clinical trials related to Muscle Physiology.
Filter by:Ageing is characterized by a decline in neuromuscular control and a progressive loss of muscle mass, strength and power, leading to reduced mobility, loss of independence, higher hospitalizations rate, and increased all-cause mortality. Several studies suggest a non-linear decay of these age-related changes. Denervation-reinnervation processes, resulting in fewer but larger surviving motor units in advanced age, start as early as age 50-60yr and can be magnified in older adults (>75yr). Significant functional consequences in daily living activities are not usually observed until approximately 50yr. However, after 50yr, muscle strength/power reduction is accelerated and becomes faster than average muscle mass loss. Most observations come from cross- sectional studies and several confounding factors associated with secondary aging, such as physical activity levels, may contribute to (or compensate for) the observed age-related reductions in neuromuscular function. Compared to cross-sectional designs, prospective ones are advantageous in their ability to investigate fundamental mechanisms by excluding inter-subjects variability. In this project, the investigators will characterize longitudinal age-related changes in motor function, physical performance and muscle aerobic metabolism with an integrated approach. The investigators aim to combine classical methods of in-vivo and ex-vivo evaluation of neuromuscular function with innovative approaches for assessing changes and interactions between neural, structural and metabolic variables in two critical phases of ageing: 55-60yrs and 75-80yrs. Within each age-group, subjects will be classified based on their functional capabilities and divided in either active or sedentary. The investigators will describe the 2-yr time course of 1) mechanisms impairing neuromuscular function (denervation-reinnervation processes); 2) interactions between muscle structural changes and neural/metabolic impairments; 3) functional and metabolic changes occurring at whole muscle as well as single fibers level. The results will extend current understanding of physiological determinants of neuromuscular alterations in aging by identifying the course and rate of changes of specific factors that mediate functional loss and disability in older adults.
Whole body vibration (WBV) is a therapeutic modality in the form of exercise on a vibrating platform with an amplitude of 2-4 mm at a frequency of 25-50 Hz, which is used with increased popularity in sports medicine and rehabilitation due to its beneficial effects on muscle strength, balance, postural control, bone formation, and circulation. Beneficial effects on muscle strength and athletic performance have been reported. Spinal reflexes explain these beneficial neuromuscular effects. However, the neuronal circuit and receptors of the reflex response have not been defined precisely. A group of researchers propose that the reflex system underlying the neuromuscular effects of WBV is the Tonic vibration reflex (TVR), whose receptor is the muscle spindle; other researchers claim that the reflex latency induced by WBV is 4-5 ms longer than the TVR latency, so it is a bone myoregulation reflex whose receptor is osteocytes. The muscle spindle has sympathetic innervation. It has been reported that in case of increased sympathetic activity, muscle spindle sensitivity may increase and short-latency stretch reflex may be facilitated. The variation of muscle spindle activity with sympathetic activity may provide an opportunity to define the nature of the reflex response during WBV. Muscle spindles are more sensitive to vibrations around 100 Hz. This study has two hypotheses: According to the first hypothesis, WBV activates muscle spindles and the reflex latency induced by WBV is the same as TVR latency, and the latency does not change with increased sympathetic activity. According to the alternative hypothesis, WBV activates osteocytes, and WBV-induced reflex latency is longer than TVR latency. With increased sympathetic activity, the WBV reflex becomes dominant and the WBV-induced reflex latency becomes shorter. The aim of this research is to determine which of these two hypotheses is valid.
Whole-body vibration (WBV) has beneficial neuromuscular effects on muscle strength increase. Supraspinal, spinal, and peripheral mechanisms have been proposed to explain these beneficial effects. The most commonly proposed explanatory mechanism is spinal segmental reflexes. However, the neuronal circuit and receptors of the reflex response have not been defined precisely. A group of researchers found that the reflex system is the Tonic vibration reflex (TVR) under the neuromuscular effects of WBV; Other researchers claim that WBV activates a different spinal reflex than TVR. Tonic vibration reflex is a polysynaptic reflex that occurs as a result of muscle spindle activation, in which more than 100 Hz vibrations are applied to the belly or tendon of the muscle. A group of researchers argues that WBV activates the spinal reflex response, but this reflex response is different from TVR. According to them, WBV-induced reflex (WBV-IR) response latency is longer than TVR latency. WBV activates TVR at very attenuated amplitude; WBV activates a different spinal reflex with longer latency at medium and high amplitude vibration. They reported that although the H-reflex, T-reflex, and TVR latency was longer in the spastic soleus muscle than normotonic soleus muscle, where the muscle spindle and Ia afferent pathway were hyperactive. However, the WBV-IR latency was similar in both spastic and normotonic soleus muscle. According to hypothesis of the present study , the reflex system activated by WBV changes depending on whether there is voluntary contraction or not: if the vibration is applied during voluntary contraction, the tonic vibration reflex is activated; In the absence of voluntary contraction (when the muscle is at rest), the bone myoregulation reflex is activated. The purpose of this research is to test this hypothesis.
Whole-body vibration (WBV) has beneficial neuromuscular effects on muscle strength increase. Supraspinal, spinal, and peripheral mechanisms have been proposed to explain these beneficial effects. The most commonly proposed explanatory mechanism is spinal segmental reflexes. However, the neuronal circuit and receptors of the reflex response have not been defined precisely. A group of researchers found that the reflex system is the Tonic vibration reflex (TVR) under the neuromuscular effects of WBV; Other researchers claim that WBV activates a different spinal reflex than TVR. Tonic vibration reflex is a polysynaptic reflex that occurs as a result of muscle spindle activation, in which more than 100 Hz vibrations are applied to the belly or tendon of the muscle. A group of researchers argues that WBV activates the spinal reflex response, but this reflex response is different from TVR. According to them, WBV-induced reflex (WBV-IR) response latency is longer than TVR latency. WBV activates TVR at very attenuated amplitude; WBV activates a different spinal reflex with longer latency at medium and high amplitude vibration. They reported that although the H-reflex, T-reflex, and TVR latency was longer in the spastic soleus muscle than normotonic soleus muscle, where the muscle spindle and Ia afferent pathway were hyperactive. However, the WBV-IR latency was similar in both spastic and normotonic soleus muscle. According to our hypothesis, the reflex system activated by WBV changes depending on vibration frequency: if the high-frequency (100-150 Hz) WBV is applied, the tonic vibration reflex is activated; if the low-frequency (30-40 Hz) WBV is applied, the bone myoregulation reflex is activated. The purpose of this research is to test this hypothesis.
We aimed in this study: 1. To compare the ultrasonographic measurements of the abdominal muscles thickness symmetry in patients with adolescent idiopathic scoliosis (AIS) and adolescent healthy individuals 2. To investigate the effect of measured thickness and symmetry on pulmonary function test.
The first aim of this study is whether the inhibitory kinesio taping application can reduce spasticity. The second aim of this study is to investigate whether the kinesio taping application have neuromodulatory activity on motor neuron and stretch reflex. Hypotheses of this study: unlike healthy cases, in patients with spastic hemiplegia 1. Inhibitory kinesio taping application can reduced spasticity 2. Inhibitory kinesio taping application can reduced motor neuron activity and stretch reflex
This study evaluates whether an increase in the ipsilateral knee flexor muscle strength transfers to the contralateral knee extensors which are not exposed to vibration, when unilateral-isolated whole body vibration (WBV) is applied to the lower extremity. In the half of volunteers the right leg were exposed vibration, while in the other half the right leg were exposed sham vibration. Muscle strength were measured with the Cybex® (Massachusetts, USA) extremity-testing system.
Previous studies reported that myoelectrical activity increased during whole body vibration (WBV). The investigators hypothesized that the change in soleus muscle length does not affect the whole body vibration induced soleus reflex muscle activity but the change in ankle angle affects the whole body induced soleus reflex muscle activity. The purpose of this study is to test this hypothesis.