Brown, Scott Robert2013-07-112013-07-112013-05https://hdl.handle.net/11299/152449University of Minnesota Ph.D. dissertation. May 2012. Major: Kinesiology. Advisors: Dr. Stacy Ingraham, Dr. Beth Lewis. 1 computer file (PDF); vi, 115 pages.The aim of this study was to assess the effects of 16 weeks of marathon training on breath-to-breath (btb) respiratory exchange ratio (RER) variability, measured by sample entropy (SampEn), in college-age, healthy novice marathon runners. Average SampEn scores for participants increased with marathon training. SampEn analysis of RER time series may detect trainability, metabolic adaptations, or provide substrate utilization recommendations with endurance training.en-USMarathonMetabolismRespiratory exchange ratioSample entropyTrainingVariabilityThesis or Dissertation