Human Muscle Stretch Reflexes: The Effects Of Stimulus Properties, Muscle State And Subject Intention
Funder
National Health and Medical Research Council
Funding Amount
$170,604.00
Summary
The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch ....The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch modulates the muscle activity such that an increase in contraction of the muscle opposes the stretch and defends the position of the joint against the external disturbance. This is the everyday situation in which stretch reflexes operate. Despite extensive investigation for over a hundred years, there is still no consensus among researchers about the behaviour of stretch reflexes nor about their role in the control of movement. Even the demarcation of reflex from voluntary muscle activity is not always certain. One of the outstanding features of stretch reflexes is the variability of their behaviour, which depends on the particular muscle involved, its level of contraction, the type of stretch and the task in which the person is engaged. This variability has made it difficult for researchers to determine the role of reflexes in the control of movement. In order to study stretch reflex behaviour in human subjects, we will measure the electrical activity of elbow muscles, the elbow position and the force generated at the joint under a variety of conditions. A series of five experiments will investigate specific unresolved issues such as the effect of subject intention on the modulation of muscle activity and how altered modulation of muscle activity may change the stiffness of our limbs. The objective of the experimental series is to fill in important gaps in the picture of the behaviour of the stretch reflex.Read moreRead less
Efficacy And Mechanisms Of Exercise Training In Diastolic Heart Failure
Funder
National Health and Medical Research Council
Funding Amount
$385,250.00
Summary
Heart failure is modern epidemic which presents a significant public health burden, due to a high mortality, frequent hospital admissions and impaired functional capacity. Although the typical heart failure patient presents with a reduced contractile function, many patients have typical heart failure symptoms but with normal contraction. The problem in these patients seems to relate to the heart's ability to fill with blood, and this entity is known as diastolic heart failure (DHF). This syndrom ....Heart failure is modern epidemic which presents a significant public health burden, due to a high mortality, frequent hospital admissions and impaired functional capacity. Although the typical heart failure patient presents with a reduced contractile function, many patients have typical heart failure symptoms but with normal contraction. The problem in these patients seems to relate to the heart's ability to fill with blood, and this entity is known as diastolic heart failure (DHF). This syndrome is most frequently due to ischemic or hypertensive heart disease, and most commonly occurs in the elderly. The optimal management of DHF is not well defined, although some drug trials are currently in progress. A number of studies have shown exercise training to improve functional capacity by 15-20% in typical heart failure. However, training has not so far been trialled in DHF. In this multicenter, multi-disciplinary study, we will study a training and control group to determine whether exercise capacity and DHF symptoms are responsive to exercise training. This work will teach us about the optimum exercise prescription, in terms of the duration and nature of training, as well as the safety and effectiveness of exercise training. By using a number of sensitive measurements of heart and vessel function (in which our group has special expertise), we will identify whether exercise training exerts its effect through improvement in vascular function and myocardial properties. If successful, the clinical implications of this study are that; 1. Exercise training will be adopted to improve functional capacity and symptoms of DHF 2. The merits of aerobic and strength training will be identified in DHF 3. Abnormal blood vessel function will be identified as a major and reversible contributor to DHFRead moreRead less
Improving Muscle Function After Injury: Novel Tissue Engineering Strategies For Exercise, Surgery And Sports Medicine
Funder
National Health and Medical Research Council
Funding Amount
$288,210.00
Summary
Muscles can be injured by excessive strains when playing sports, in road and workplace accidents, and during plastic and reconstructive surgery. Some surgeries require an unavoidable interruption to the muscle's normal blood supply (called 'ischaemia'). Subsequent return of the muscle's blood supply (reperfusion) is problematic in that a severe secondary muscle injury can ensue mediated by the influx of damaging free radicals when blood flow is restored. Tissue-engineering provides a novel thera ....Muscles can be injured by excessive strains when playing sports, in road and workplace accidents, and during plastic and reconstructive surgery. Some surgeries require an unavoidable interruption to the muscle's normal blood supply (called 'ischaemia'). Subsequent return of the muscle's blood supply (reperfusion) is problematic in that a severe secondary muscle injury can ensue mediated by the influx of damaging free radicals when blood flow is restored. Tissue-engineering provides a novel therapeutic approach to restore muscle structure and function to damaged muscles after injury or disease. Our recent research using controlled release of growth factors from biodegradable hydrogels has exciting application for muscle repairafter injury. We will utilize these cutting edge tissue engineering strategies to deliver to damaged muscles a hydrogel containing controlled delivery (slow release) microcapsules loaded with an anabolic agent (the beta-agonist, formoterol) and-or a growth factor (IL-15) designed to enhance functional muscle repair after three distinct but clinically relevant models of muscle injury: a) crush injury: A model for muscle injuries on the sports field, in the workplace, and those associated with road trauma; b) ischaemia-reperfusion injury: a model for muscle damage associated with surgical interventions, muscle transfers for functional restoration, and other injuries associated with plastic and reconstructive surgery; and c) contraction-induced injury: a model for strain injuries such as hamstring muscle tears that can occur on the sports field. After injury we will assess functional muscle repair using a comprehensive series of histological, biochemical, molecular, immunochistochemical, and physiological techniques. The research has broad application to exercise and clinical medicine; including sports, emergency and rehabilitation medicine, and plastic, reconstructive, and orthopaedic surgery.Read moreRead less
Targeted Strength Training To Improve Functional Walking Capacity Of Adolescents And Young Adults With Cerebral Palsy
Funder
National Health and Medical Research Council
Funding Amount
$263,449.00
Summary
Cerebral palsy is the most common cause of disability in children. Caused by damage to the brain in early childhood cerebral palsy leads to muscle weakness and difficulties in walking. There is no cure for cerebral palsy, but we can help the weak muscles . The purpose of this trial is to establish that exercises to strengthen the weakest muscles will help the walking ability of teenagers and young adults with cerebral palsy, as they make the transition to independence and adulthood.
Exertional Dyspnoea With Increased Filling Pressure - Mechanisms And Treatment Strategies
Funder
National Health and Medical Research Council
Funding Amount
$387,793.00
Summary
Patients with early heart disease often present with shortness of breath with exercise, as myocardial reserve at that stage is usually sufficient to maintain normal function at rest . Indeed, much myocardial dysfunction may originate from the modern lifestyle, including inactivity, obesity, the metabolic syndrome and type II diabetes. The potential benefits of making a definitive early diagnosis are large, because it seems more likely that an impact can be made on the disease process (and theref ....Patients with early heart disease often present with shortness of breath with exercise, as myocardial reserve at that stage is usually sufficient to maintain normal function at rest . Indeed, much myocardial dysfunction may originate from the modern lifestyle, including inactivity, obesity, the metabolic syndrome and type II diabetes. The potential benefits of making a definitive early diagnosis are large, because it seems more likely that an impact can be made on the disease process (and therefore, outcome) than with late stage disease. Current treatment strategies are expensive and because they are directed at end-organ damage (heart failure, heart attacks etc), rather ineffective. This multispecialty, multidisciplinary group will undertake a series of unique studies aimed at identifying early cardiovascular disease. The strategy will involve detection of abnormal filling behaviour at stress echocardiography, with randomization into longterm and short-term trials to examine various therapeutic strategies. Sensitive new cardiovascular imaging techniques will be used to detect preclinical abnormalities in the structure and function of the heart and vasculature, facilitating a mechanistic understanding of the process of increasing filling pressure with exercise.Read moreRead less
The Effects Of A Two Year Randomised Exercise Intervention On Markers Of Bone Turnover In Postmenopausal Women
Funder
National Health and Medical Research Council
Funding Amount
$43,573.00
Summary
Osteoporosis is a condition where the bones become more fragile and can break more easily. In Australia after age 60, three out of every five women and three out of every ten men will fracture a bone. When people fracture a hip they lose their independence and become much less mobile. Exercise is one lifestyle approach which may help in preventing osteoporosis by slowing bone loss and keeping the muscles strong. Previous research has not been able to clearly demonstrate the usefulness of exercis ....Osteoporosis is a condition where the bones become more fragile and can break more easily. In Australia after age 60, three out of every five women and three out of every ten men will fracture a bone. When people fracture a hip they lose their independence and become much less mobile. Exercise is one lifestyle approach which may help in preventing osteoporosis by slowing bone loss and keeping the muscles strong. Previous research has not been able to clearly demonstrate the usefulness of exercise due partly to the difficulty in getting people to exercise for a least one year, which is how long bone studies must be carried out for. We have conducted two large research studies in women past the menopause where they have done weight training exercises. In the previous study we showed the greatest increase in bone mass occurred in those women lifting the heaviest weights. In a recently completed two year study in 126 woman, which forms the basis of this proposal, we found a weight training program was effective at increasing the bone mass at the hip, a common fracture site. The fitness group did not show any increase. So although we have been able to show this type of exercise helps increase bone mass we don't know how the bone is able to respond to this. The question we wish to address with this proposal is does exercise slow the breakdown of bone or does it help form new bone? The best way to be able to answer this question is by measuring certain products in blood, known as bone markers. Bone is continually turning overthese markers are released from bone into the blood. By studying these bone markers in blood samples taken from the subjects over two years it will helps us determine how exercise is affecting bone. From our previous studies we know that weight training can help slow bone loss. By measuring the bone markers we will then be able to make recommendations to people on how exercise will help prevent bone loss.Read moreRead less
A Phase III Clinical Trial Of Exercise Modalities On Treatment Side-effects In Men Receiving Therapy For Prostate Cancer
Funder
National Health and Medical Research Council
Funding Amount
$519,330.00
Summary
Hormone therapy is very effective for treating prostate cancer however it produces a number of side effects including muscle and bone loss, fat gain, and increased risk of death from heart disease and diabetes. In other populations physical exercise has proven particulary effective for preventing such problems however no long term studies with prostate cancer patients have ever confirmed this. Knowledge gained from this study has potential to markedly reduce suffering and increase survival.
Understanding The Metabolic Consequences Of Impaired AMPKa2 And NNOS� In Skeletal Muscle: Implications For The Metabolic Syndrome
Funder
National Health and Medical Research Council
Funding Amount
$575,527.00
Summary
The inability of muscle to utilise sugar from the blood is a major problem that contributes to obesity and Type 2 diabetes. Since the number of people with these diseases will at least double by 2030, we need to find out what causes this problem. We will examine whether two muscle proteins that are impaired in obesity and Type 2 diabetes are also responsible for impaired sugar utilisation. We think that increasing these muscle proteins will fix the _sugar problem�, and remedy these diseases.