Living Fit (LivFit) with HIV: Reducing inflammation and improving vascular function among older persons with HIV Open Access
Irwin, Crista (Spring 2023)
Abstract
Background: Persons with HIV experience endothelial dysfunction due in part to chronic inflammation that increases their risk for poor vascular function and cardiovascular disease (CVD). Routine moderate to vigorous aerobic exercise intensity has been shown to improve inflammation and vascular function, but the level of exercise adherence required for improvement among older persons with HIV (OPWH) has not been established. In addition, validation studies for the activity monitors to determine exercise intensity was also not established in OPWH. The purpose of this study was to: conduct a systematic review on the validity and accuracy of the FitBit Charge 2 for measuring aerobic exercise intensity level; utilize data from a secondary analysis to test the level of exercise adherence on measures of inflammation, and endothelial vascular function among OPWH.
Methods: Participants (n=115, mean age 55, 65% male, 82% Black) were enrolled in the 2-arm randomized controlled trial (RTC) Healing Hearts and Mending Minds parent study. The intervention group consisted of a progressive walking program (Let’s Move) compared to attention control participants (Let’s Flex) which were evaluated at baseline (BL) for cardiorespiratory fitness using the modified Balke VO2 max test. Inflammatory biomarkers Interleukin-6 (IL6), Tumor necrosis factor (TNF), and soluble C-differential-14 (sCD14) were drawn at BL, 3, 6-, and 12-months. Endothelial vascular function was measured by flow-mediated dilation (FMD) at BL and 6-months. Participants were provided with activity trackers and an exercise prescription based on their individual target heart rate at 60-70 % intensity and progressed to a minimum of 300 minutes per week. T-test were also used to compare the changes in inflammatory values between adherent and non-adherent participants in the exercise intervention group between BL and 3-, 6-, and 12-month timepoints. Change in FMD was examined between both groups from baseline to 6-months. Multilevel linear modeling was performed within the exercise intervention group to examine the incremental change in the biomarker values over time in association with a cumulative adherence level. Cumulative exercise was calculated by adding up whether exercise adherence was met (yes=1, no=0) at each 3-, 6-, and 12- month timepoint (i.e. cumulative adherence values ranged from 0 to 3).
Results: A systematic review of validation studies suggests that the Fitbit Charge2 activity tracker adequately measured HR at moderate intensity exercise levels. Over 60% of the participants in the intervention group maintained adherence to >300 minutes of moderately to vigorous (60-70% HR maximum) exercise throughout the 12-month study duration. Attrition rate was <10% in both groups over the study duration. The change in FMD was not significant between the intervention and attention control groups but was significantly improved among the participants who were adherent to their exercise prescription at least 70% of the time compared to those who were not adherent (adherent = 0.58, not adherent = -1.61, p=0.025) at 6-months. Among the participants in the exercise intervention who were adherent to their exercise prescription at least 70% of the time, sCD14 and TNF values decreased without statistical significance with small to moderate effect sizes (0.42 and 0.35 respectively).
Conclusions: Findings from this study indicated that OPWH were willing to remain engaged in a study over a 12-month period with very low attrition rates observed. Although reductions in the inflammatory markers were minimal, this was likely due to participants being well-controlled on their antiretroviral therapy (ART) with little room for improvement or change. Higher exercise adherence was associated with improved endothelial vascular function among OPWH and may lower CVD risk. Future studies are needed to examine exercise dose and modes on CVD risk reduction among OPWH.
Table of Contents
Chapter I: Introduction 6
Statement of the problem 6
Inflammation and HIV 6
Endothelial Function and HIV 7
Exercise, inflammation, and endothelial function in HIV 8
Exercise adherence 8
Exercise and physical activity measurement in HIV 9
Motivation to exercise 10
Purpose 10
Specific Aims 11
Manuscript descriptions 12
Conceptual Framework 12
Figure 1: Concept framework 12
Background and Significance 13
Effect of exercise on CVD 13
The role of inflammatory biomarkers in CVD etiology and disease
progression in PWH 16
Endothelial vascular function and CVD/HIV 17
Flow-mediated dilation 18
Exercise and endothelial function 18
Research Methods and Design 19
Parent Fitbrain Study design 19
Table 1: Exercise prescription 19
Intervention group 19
Table 2: Fitbit assessment schedule 20
Control group 20
Parent FitBrain study recruitment and sample 21
Human Subjects and informed consent 21
Sample size and power calculation 21
Table 3: Adherent versus non-adherent sample sizes 22
Variables and Measures 22
Sociodemographic variables 22
Table 4: Demographics 23
Clinical variables 23
Table 5: Baseline clinical variables 23
Parent study data collection 23
Cardiorespiratory fitness testing 23
AIM 1 data collection: Fitbit tracker validation. 24
AIM 2 data collection: Flow-mediated dilation 24
Figure 2: Flow-mediated dilation process 25
AIM 3 data collection: Inflammatory biomarker collection 25
Table 6: Variables, measures, and timepoint 26
Data analysis 26
Summary 28
References 29
Chapter 2: Systematic Review of Fitbit Charge 2 Validation Studies for Exercise
Tracking 37
Chapter 3: Higher exercise adherence among older persons with HIV is associated
with improved flow-mediated dilation 56
Chapter 4: Higher exercise adherence lowers inflammation among older persons
with HIV 81
Chapter 5: Integrative summary 104
Strengths and limitations 107
Implications and future directions 108
Conclusions 109
About this Dissertation
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Primary PDF
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Living Fit (LivFit) with HIV: Reducing inflammation and improving vascular function among older persons with HIV () | 2023-04-13 10:53:20 -0400 |
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Supplemental Files
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Permission for figure (Permission for Fig. 1, Chapter III) | 2023-04-07 14:40:51 -0400 |
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