First Advisor

Stewart, Laura K.

First Committee Member

Hydock, David S.

Second Committee Member

Pullen, Nicholas A.

Third Committee Member

Haughian, James M.

Degree Name

Doctor of Philosophy

Document Type

Dissertation

Date Created

12-2025

Department

College of Natural and Health Sciences, Kinesiology Nutrition and Dietetics, KiND Student Work

Embargo Date

12-2026

Abstract

Introduction: The purpose of this study is to explore the effects of 2-weeks of high intensity interval training (HIIT) or cyclic hyperventilation with retention (CHR) on measures of overall health, function of the autonomic nervous system (ANS), mental health, circulating concentrations of c-reactive protein (CRP), natural killer cell (NKC) numbers, and NKC cytotoxicity. It was hypothesized that participants in the HIIT group (HIG) and CHR group (CHG) will experience similar improvements in measures of overall health through the improvement of sleep quality measured by the Pittsburgh Sleep Quantity Index (PSQI) and the reduction of sickness related symptoms measured by the Wisconsin Upper Respiratory Symptom Survey (WURSS), reductions of depression, anxiety, and stress scores measured by the Depression, Anxiety, and Stress Scale (DASS-21), reductions of systemic inflammation measured by CRP concentration, and improved immune function as measures of NKC counts and improved NKC cytotoxicity as measured by a human myelogenous leukemia cell line (K562) counts and the proportion of dead K562 cells (DEADPROP) after a 4 hour co-culture with peripheral blood mononuclear cells (PBMC), when compared to a control group (COG) after the 2-week intervention. Methods: A total of 36 healthy participants experiencing mild or greater scores of depression, anxiety, and stress, were recruited from the University of Northern Colorado and surrounding communities, then randomly assigned to one of three groups: HIG (n = 12), CHG (n = 12) or COG (n = 12). Participants completed measures of body size, body composition, and a cardiorespiratory endurance test at the pre-intervention timepoint and mental health surveys, ANS function, and a fasted peripheral blood draw at the pre- and post-intervention timepoints. Participant serum samples were used to quantify resting concentrations of CRP, and heparinized whole blood was used to isolate PBMCs to quantify NKC cells, defined by CD56+ mean fluorescent intensity (MFI). Isolated PBMCs were co-cultured with K562 cells at an effector to target ratio of 40:1 to assess NKC cytotoxicity of each participant. Live K562 cells were quantified by Calcein-AM (CAM), and CD71+ MFI for live K562 counts and used to calculate DEADPROP. All data are presented as mean ± standard deviation with a significance of α = 0.05. A One-way ANOVA or Kruskal Wallace test was used to identify significant differences among groups at the pre-intervention timepoint and a 3x2 mixed model ANOVA or nonparametric ANOVA was used to identify significant effects and interactions. Results: No significant differences among intervention groups were observed at the pre-intervention timepoint with respect to all study outcomes. A significant time effect was observed for mental health-associated measures, circulating biomarkers of stress, NKC counts, NKC phenotype counts, and live K562 cells. A reduction of depression (-22%), anxiety (-27%), stress (-19%), DASS total scores (-29%), CRP concentration (-19%), NKC numbers (-12%), CD56bright expressing cells (BRIs) (-16%), CD56dim expressing cells (DIMs) (-11%), live K562 cells (-14%) and an increase in DEADPROP (5%) was observed when pre-intervention data were compared to post intervention data. A significant group x time interaction was observed for live K562 cells, though post-hoc comparison was not significant. Additionally, a significant group x time interaction for DEADPROP was observed and post-hoc comparison revealed a significant effect of HIG with a 19% increase in DEADPROP(p = 0.006). Discussion: While a significant increase in DEADPROP was observed for HIG, a similar relative result was observed when comparing the exercise time requirements for HIG and CHG. The increase of DEADPROP for HIG was 360% greater than CHG, yet the required time for HIG was also 360% greater than CHG. Conclusion: Furthermore, CHR may be a viable option for improving NKC cytotoxicity for those individuals not suitable for HIIT, yet this study suggests that HIIT is preferred for the greatest possible improvement of immune parameters.

Abstract Format

html

Language

English

Extent

179 pages

Rights Statement

Copyright is held by the author.

Digital Origin

Born digital

Download

Available for download on Tuesday, December 01, 2026

Share

COinS