MacInnis, MartinAjayi, Oluwatimilehin Olamilekan2024-01-032024-01-032023-12-21Ajayi, O. O. (2023). An assessment of detrended fluctuation analysis (Alpha 1) in demarcating exercise intensity, quantifying training load, and predicting performance (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/117823https://doi.org/10.11575/PRISM/42666The short-term scaling exponent of detrended fluctuation analysis (DFA α1) can be used to measure exercise stress in humans. Based initially on theoretical knowledge, it was suggested that DFA α1 values of 0.75 and 0.5 aligned with the aerobic (i.e., gas exchange threshold (GET)) and anaerobic thresholds (i.e., respiratory compensation point (RCP)), respectively. Regarding constant work rate (CWR) exercise, DFA α1 has been studied while cycling at a fixed intensity with varied cadence. Accordingly, this study aimed to determine the utility and reliability of DFA α1 during ramp incremental (RI; phase one) and CWR exercise (phase two). Twenty (10M, 10F) and fifteen (10M and 5F) healthy recreationally active individuals participated in phases one and two of the project, respectively. Although not different between fast (25 W·min-1; FR) and slow (12.5 W·min-1; SR) RI tests (p=0.192), DFA α1 values at GET (FR: 1.18±0.40; SR: 1.32±0.42) were significantly larger than 0.75 (p<0.001). DFA α1 values at RCP were significantly larger than 0.5 in the slow ramp (0.64±0.24; p=0.020) and were significantly greater compared to the fast ramp (0.54±0.23; p=0.029). DFA α1 values at GET and RCP had moderate (ICC=0.654; p=0.429) and poor reliability (ICC=0.401; p=0.169), respectively. DFA α1 values decreased during 20-min of CWR exercise (p<0.001), with significant differences between the first and last 5 min (0.84±0.23 vs. 0.58±0.22; p=0.003), and DFA α1 was lower in the final 5 min of the second 20-min (0.44±0.14) compared to the final 5 min of the first 20-min (0.57±0.20) of a 40-min CWR bout (p=0.002). DFA α1 at the same relative moderate intensity of exercise (65% GET) declined during each bout, with the lowest values observed after time to task failure tests (p<0.05). This thesis adds to the growing body of work surrounding the use of heart rate variability metrics, specifically DFA α1, during exercise, but these mixed results highlight the need for additional research on DFA α1 values during various exercise protocols.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Exercise physiologySciencesWearable technologyHeart rateHeart rate variabilityExerciseKinesiologyPhysiologyEducation--SciencesEducation--Technologymaster thesis