NIRS and Exercise Intensity in Patients With FLIA

Plain-language summary

The research objectives of this project are to increase the understanding of pathophysiology and performance limitations related to sport-related flow limitation in the iliac artery (FLIA) using non-invasive measurement of muscle oxygenation at the working muscles of the leg and mechanical power output recorded during cycling exercise. Skeletal muscle oxygenation measured with Near-Infrared Spectroscopy (NIRS) is growing more accessible for use by coaches, teams, and individual athletes for use in performance testing. Describing how muscle oxygenation profiles in endurance athletes diagnosed with FLIA differ in comparison with healthy athletes may allow the use of this non-invasive, accessible measurement device for the screening of athletes at risk of developing FLIA. The relevance of this work is that FLIA imposes risk of irreversible injury to the main artery of the leg in endurance athletes, limiting their ability to participate in exercise, with further consequences for health, fitness, and quality of life. Currently, the early course of this progressive condition is poorly understood, as early detection is difficult and hence appropriate treatment is often delayed. If impairment becomes severe, often more invasive (and risky) treatment is necessary. Earlier detection and monitoring of FLIA may allow for improved patient management and outcomes. The design of this experiment will compare a patient group of trained cyclists diagnosed with FLIA, to healthy control subjects including cyclists of a similar fitness level without signs of FLIA. Both groups will perform an incremental ramp cycling test and an intermittent multi-stage cycling exercise test. Incremental ramp cycling testing is used as part of clinical diagnosis of FLIA, as well as performance (eg. VO2max) testing of healthy athletes. Multi-stage exercise protocols are also often used for performance testing of endurance athletes and allows for observation of (path)physiological responses during submaximal work stages. Outcome measures of muscle oxygenation kinetics with NIRS and cycling power will be analysed and compared between patients and healthy subjects.

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