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Measuring Exhaustion Response: Example using Vagal Variance

Measuring Exhaustion Response: Example using Vagal Variance. Sean Collins. Evidence of Reduced Vagal Cardiac Control Variability in Exhausted Subjects & High Strain Job Subjects. Purpose :

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Measuring Exhaustion Response: Example using Vagal Variance

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  1. Measuring Exhaustion Response: Example using Vagal Variance Sean Collins

  2. Evidence of Reduced Vagal Cardiac Control Variability in Exhausted Subjects & High Strain Job Subjects • Purpose: • Present methods and propose hypotheses to test a component of the Stress Disequilibrium Theory based on “Regulatory System Variance” • HRV Project Background • Regulatory System Variance • HRV Project Methods • Determination of Exhausted Subjects • Repeated measures ANOVA

  3. Regulatory System Variance: Strain & Exhaustion Hypothesis • High Frequency Variance components of HRV reflect Vagal system activity • Vagal system is a regulator of the cardiac system • Vagal system variance reflects Vagal system capacity to adapt to regulatory demands: Regulatory System Variance – i.e. Ashby’s Requisite Variety • Reduced Control (High Strain) & Exhaustion may lead to a reduction in Vagal system regulatory capacity – and therefore reduced Regulatory System Variance

  4. Determination of Exhausted Subjects • Job Content Questionnaire Exhaustion Items • Unusually tired in the morning • End of the day, completely exhausted mentally and physically • “Most of the time” response required for both items • Four subjects reached pre-determined criteria for “exhaustion” • 3 “exhausted subjects – high strain jobs • Hybrid methodology

  5. Regulatory System Variance – Controlled / Controlled Relationship System Regulation HFP Time Series (Vagal Control) 4 Hours (= 48 Epochs) Beat-to-Beat Variability RR Interval Series 5 – Minutes Frequency Analysis – HFP (.15-.4 Hz) 1 Epoch

  6. Line of Identity Poincaré Plot for Entire Monitoring Period

  7. Poincaré Plot for Low Strain Subject at Work R2 = .552

  8. Poincaré Plot for High Strain Subject at Work R2 = .641

  9. Poincaré Plot for Exhausted Subject at Work R2 = .785

  10. Short Term Variation as Determined by Poincaré Plot Residuals

  11. Repeated Measures ANOVA

  12. Variance – Measurement Methods & Results Shape of Variance in Vagal Control

  13. Variance – Measurement Methods & ResultsData Variance > 1 σ: Vagal Cardiac Regulation

  14. Discussion Limitations • Sample size • Linkage between Reduced Regulatory Variance and disease • Identification of Reduced Regulatory Variance indicating reduced adaptive capacity

  15. Discussion Preliminary evidence of: • Reduced regulatory system variance of the vagal system in exhausted subjects during the workday that lasts into the hours following work • Reduced regulatory system variance of the vagal system in high strain subjects that seems to drop significantly during recovery hours • Clearly requires further study

  16. End of Measuring Exhaustion Response….

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