Non invasive measurement of muscle oxygenation in elite athletes in the field

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A major problem in many physiological measurements is that the act of performing the measurement can itself alter the system that is under observation. The challenge for scientists is to develop techniques which allow the non invasive assessment of physiological processes. A technique called Near Infrared Spectroscopy (NIRS) has previously been used to measure the wavelength dependence of the optical absorption of blood and therefore its oxygen content (highly oxygenated arterial blood is bright red whilst oxygen depleted venous blood appears purple/blue in colour). In principle NIRS allows for the measurement of the oxygen saturation of the muscle. Muscles use oxygen to assist in the conversion of food energy (carbohydrate/fat) into the useable chemical energy that can drive muscle contraction and allow an athlete to run, cycle and swim. Exercise uses up oxygen and therefore how much oxygen is in the muscle (its oxygen saturation) is a measure of whether the oxygen being delivered is keeping up with its consumption. In aerobic exercise there is sufficient oxygen; in anaerobic exercise this is not the case. Achieving gold in the 2012 Olympics has become a top priority for UK Sport. There are many factors that will influence the position of Team GB in the medals table in 2012, including the development of optimised training regimes for elite athletes. Informed development of effective training strategies requires coaches to be given real time feedback on an athlete's performance at the trackside. Currently there is a scarcity of available devices that provide reliable and accurate physiological monitoring of elite athletes in the field. There are currently very few available methods which allow us to measure physiological changes in an athlete while they are training in the field. In theory NIRS methods could be used to measure muscle oxygenation in training athletes. However current commercial NIRS machines are large, heavy and non-portable.The aim of this feasibility project is to develop a non-obtrusive, battery driven, compact, NIRS device that measures local absolute muscle oxygen saturation and transmits this data via a wireless link to the coach in real time. Feedback from elite athletes and coaches at Essex (and via UK sport) will inform the design to ensure that the device will be acceptable to all athletes and will not compromise athletic performance. In parallel with the design of the prototype device we will be testing how the new technology could be used to enhance sports performance. We will focus initially on events, such as running and cycling, where it is easy to make complex biochemical and physiological measurements in the laboratory (using analysis of the exhaled air and measurements in blood samples). Our aim is to understand in detail the use of NIRS measurements in this laboratory setting using tests that attempt to recreate sporting events. Armed with this knowledge we will ultimately be able to apply the technology in the field during the training of an elite athlete. Of many possibilities we will initially focus on two uses for NIRS / optimising warm-up for athletes in sprint events and designing optimal pacing strategies (when to go fast and when to conserve energy) in endurance events. Beyond this feasibility study our long-term aim is to develop a device capable of providing a number of physiological measures for use in a wide range of sports and extreme environments including swimming and altitude training. Whilst we feel this device has the possibility of giving UK sport an edge in 2012, its manufacture will also be part of the Olympic post-2012 dividend, as it will have significant use in medical applications e.g. assisting paraplegics in improving muscle function and in investigating brain injury in patients.