The effect of short-term eccentric exercise training on inflammation and glucose tolerance in early stage type 2 diabetics

Research Spotlight - in progress

Ben Rattray, Walter Abhayaratna*, Gordon Waddington, Tegan Meredith*, Nick Ball and Vicki Deakin

Insulin pump with infusion pump

Staff  *The Canberra Hospital

Background: In Australia, physical inactivity is attributable to ~$400m per year in direct health care costs, although the indirect costs on society are estimated to be much higher. Physical inactivity can lead to a state of low-grade inflammation associated with many disease states including diabetes. Exercise can reverse this trend and both acute and chronic moderate exercise can reduce systemic inflammation. Specifically relating to metabolic disease states, exercise is known to ameliorate insulin resistance and glucose tolerance. However, compliance remains a major issue in physical activity yielding the health benefit gained from any exercise increasingly important.

Physical activity targeting muscle adaptation is desirable for metabolic disease states such as diabetes because skeletal muscle strongly regulates blood glucose and fat metabolism. At the cellular level eccentric exercise greatly increases stress on the muscle relative to concentric exercise at a lower metabolic and cardiovascular cost. Eccentric exercise thus offers the advantage of limiting many of the risks associated with exercise in at risk populations (i.e. increases in HR and BP) and thus better suited to address complex chronic diseases. A single bout of eccentric exercise can create a state of inflammation and transiently impair insulin-signalling pathways but this negative response is prevented during a second exercise bout. Several positive cellular adaptations can occur after less than a week of eccentric training. These observations suggest a much greater stimulus for adaptation than typically observed during concentric exercise.

Recent research investigating the effect of eccentric exercise training in impaired glucose tolerance has been poorly controlled. Downhill hiking prescribed over two months however has been shown to reduce systemic inflammation markers and may improve insulin resistance in apparently healthy individuals although no direct measure of insulin resistance was carried out. The proposed research will address this gap in the literature.

Plain English: Exercise forms an important part of the treatment of type 2 diabetes. Specific recommendations on the type of exercise that should be performed are less clear. Issues relating to exercise prescription include potential complications of exercise and compliance to an exercise program. Eccentric contractions occur during exercise when the muscle is lengthening, such as during weight training or walking down stairs or downhill. This can result in some initial muscle soreness but research suggests that eccentric exercise may provide a strong stimulus for positive adaptations to the muscle, resulting in improved glucose control and health outcomes. It is also thought that the improvements experienced during this type of exercise will be greater than those of other types of exercise at a similar heart rate level. Greater health benefits may be gained from less physical activity, promoting increased compliance to exercise programs. This project will assess how your glucose control and markers of inflammation respond to a two week bout of either concentric of eccentric cycle training.

Links: Blog post, in the news blog post, another in the news blog post.

The impact of varied physical load on an executive function task

Research Spotlight - in progress

Ben Rattray, Disa Smee and James Neill
Staff

Abstract: Exercise tends to facilitate cognitive performance although there are a number of caveats to this phenomenon. Higher levels of cognitive function appear influenced by the length, intensity and perhaps type of exercise. Interactions generally accepted to interfere in peripheral exercise physiology including heat, altitude and access to fuel can also have profound influence on cognition. Studies of the interaction between acute exercise and cognition tend to focus on constant load or incremental exercise last only a few minutes. These protocols replicate the demands of few (if any) true life sporting or occupational demands that typically involve periods of high and low intensities. It has been proposed that a cognitive reserve exists and that cognitive performance will not deteriorate until the amount of resources is insufficient to deal with both physical and cognitive tasks. It is intuitive that, if this is the case, the reserve will not be challenged until conditions are considerably taxing. This study’s primary aim is to evaluate the impact of varied physical workload on in executive function and a range of physiological correlates.

Plain English: Mental, or cognitive performance, is often improved during steady moderate exercise. Decision making however is often conducted under conditions in which the physical requirements are varied and heavy (e.g., sporting setting, emergency services and military operations). There is some evidence to suggest that heavy exercise, temporarily impairs cognitive performance, but it is unknown how changes in physical load will impact on decision making. The outcomes of the study are likely to influence physical preparation and strategies aimed at limiting any deterioration in cognitive performance during physically stressful conditions in both sporting and occupational settings.

Image is Oringen 458 by Ultimate-Orienteering.

The effect of controlled frequency breathing on the physiology and stroke characteristics of elite swimmers

Research Spotlight - in progress

Courtney McGowan
Bachelor of Sport Studies (Honours) student

Supervisors: Ben Rattray and Keith Lyons

Abstract: The use of controlled frequency breathing (CFB) or 'hypoxic' breathing is a common training method used by competitive swimmers. CFB is not simply breath holding; it involves the swimmer restricting voluntarily the frequency of their breathing for a set number of strokes. The reduction in frequency of breathing has implications for both the physiological and mechanical components of swimming performance. Physiologically, a reduction in breathing frequency can induce a state of hypoxia, and subsequently an increase in blood lactate. This added physiological stress on the swimmer may simulate that experienced during competition. Mechanically, changes in breathing pattern may contribute also to improvements in stroke coordination/mechanics and subsequent performance. This study will examine the effects of CFB on a swimmer's physiological responses, stroke mechanics and performance under conditions of maximum effort. Stroke characteristics such as stroke rate and stroke length, and the physiological parameters of blood lactate, pH, gas concentrations, and heart rate and performance times will be monitored and analysed. It is anticipated that the outcomes of this research will allow for an improvement in the understanding of elite swimmers' responses to CFB and how CFB could be used in elite training programs and competitive racing to improve performance.

Plain English: A variety of different training methods are employed by those who coach elite swimming; however a method that has been utilised continuously over the past few decades and recently has gained more support is controlled frequency breathing (CFB) or 'hypoxic' breathing. This method involves the swimmer restricting the number of breaths from their normal breathing pattern of 1 breath every 2 or 3 strokes to a pattern of 1 breath every 5+ strokes. In theory, CFB limits the air exchange in the lungs, therefore reducing the oxygen concentrations in pulmonary circulation and decreasing the oxygen supply to working skeletal muscles. This study will examine the physiological and stroke mechanic responses to the use of this training method. The characteristics of stroke rate and stroke length along with the blood based parameters of lactate, heart rate, pH and gas concentrations and performance times will be analysed. As this method is used commonly in training with the belief that it will elicit an improvement in performance, the primary focus of the report will be to demonstrate the positive and negative effects of the method on athletic achievements.
Image is Cold Steel Triathlon by UNC - CFC - USFK.

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Posted By Ben Rattray to UCNISS at 6/22/2010 02:03:00 PM