The Influence of Cardiorespiratory Fitness on Firefighter Cardiovascular Health Under Exercise Conditions

NCT04514354 | Completed

• 1 other identifier: H14-183HH
• Study Type: interventional
• Target: 21
• Locations: 1 country
• Sites: 1

Brief Summary

Sudden cardiac death (SCD) is the number one cause of on-duty firefighter death. It is most likely to occur in adults who are not physically fit that engage in sudden vigorous exercise. Cardiorespiratory physical fitness (also known as aerobic fitness) is a major heart disease risk factor. In FIT and FIRED UP, the study investigators looked at the influence of cardiorespiratory fitness on blood pressure, heart rate, and other heart markers taken from the blood before and after a vigorous exercise test to maximal effort among firefighters from a local fire department in Connecticut. In addition, the investigators also looked at how lifestyle habits including physical activity, nutrition, stress, and sleep may influence our findings. It was hypothesized that aerobically fit firefighters would show less stress on their heart than unfit firefighters.

Conditions

Cardiovascular Diseases; Post-Exercise Hypotension

Keywords

Firefighters; Post-Exercise Hypotension; Cardiovascular Disease

Outcome Measures

Primary Outcomes (7)

• Change in Ambulatory Blood Pressure (ABP)

  Subjects were attached to an Oscar2 automatic noninvasive ABP monitor (Suntech Medical Instruments Inc., Raleigh, North Carolina, USA) on the nondominant arm to be worn until the next morning. The ABP monitor was programmed to record BP at regular intervals three times per waking hour and two times per sleeping hour.

  ABP was measured at the conclusion of Visits 3 and 4 during weeks 3 and 4.

• Change in Resting Blood Pressure

  Resting BP was measured according to the American Heart Association (AHA) standards using an automated BPTRU monitor (BPTRU Medical Devices, Coquilam, British Columbia, Canada). Subjects were seated for 5 minutes and then BP was measured three times, 1 minute apart in each arm. If the readings obtained were within 5 mmHg, these values were averaged and recorded as resting BP. If these readings did not agree within 5 mmHg, up to three additional readings were taken. If there were three readings obtained that agreed within 5 mmHg, these values were averaged and recorded as resting BP. If after the additional readings were taken and there were not three readings obtained that agree within 5 mmHg, the three closest values were averaged and recorded as resting BP.

  Resting BP was measured during Visits 3 and 4 during weeks 3 and 4.

• Change in Fasted Blood Sampling

  The fasting blood sampling occurred prior to and immediately after the GEST and was performed to obtain lipid-lipoprotein profiles and baseline biomarkers associated with cardiovascular disease. A trained phlebotomist collected five tubes of venous blood (52 cc or 3.5 tablespoons) from the antecubital vein of each subject. Serum total cholesterol (mg/dL), triglycerides (mg/dL), high-density lipoprotein cholesterol (HDL-C) (mg/dL), and low-density lipoprotein cholesterol (LDL-C) (mg/dL) were determined by colorimetric enzymatic assays. Serum glucose (mg/dL) was determined by enzymatic/spectrophotometric methods.

  The blood sampling occurred at Visit 3 or 4 during the GEST Visit during week 3 or 4.

• Change in Fasted Blood Sampling

  The fasting blood sampling occurred prior to and immediately after the GEST and was performed to obtain lipid-lipoprotein profiles and baseline biomarkers associated with cardiovascular disease. A trained phlebotomist collected five tubes of venous blood (52 cc or 3.5 tablespoons) from the antecubital vein of each subject. Serum insulin (uIU/mL) was determined by radioimmunoassay.

  The blood sampling occurred at Visit 3 or 4 during the GEST Visit during week 3 or 4.

• Change in Fasted Blood Sampling

  The fasting blood sampling occurred prior to and immediately after the GEST and was performed to obtain lipid-lipoprotein profiles and baseline biomarkers associated with cardiovascular disease. A trained phlebotomist collected five tubes of venous blood (52 cc or 3.5 tablespoons) from the antecubital vein of each subject. High sensitivity-C-reactive protein (mg/L) was determined by immunoturbidimetry.

  The blood sampling occurred at Visit 3 or 4 during the GEST Visit during week 3 or 4.

• Dietary Intake

  Usual dietary and alcohol intake were measured using the National Health and Nutrition Examination Survey (NHANES) semi-quantitative Food-Frequency Questionnaire. The NHANES Food Frequency Questionnaire is a validated tool for measuring dietary intake of both macro- and micro-nutrients based on 127 food items. Subjects were asked to self-report their average daily consumption of 124 food items. The data derived from the Food Frequency Questionnaire were coded and analyzed by members of the National Cancer Institute utilizing Diet\*Calc software v1.4.3 (Bethesda, MD) in order to produce daily food frequency estimates of the 127 nutrient and dietary constituents. The Diet\*Calc software analyzed Diet History Questionnaire data and generated nutrient and food group intake estimates from the Diet History Questionnaire.

  The questionnaire was filled out during Visit 3 or 4 at the Control Visit during week 3 or 4.

• Peak Oxygen Consumption

  VO2peak was measured by the maximal graded exercise stress test (GEST). The VO2peak test is the gold standard measure of cardiorespiratory fitness.

  The GEST took place either during Visit 3 or 4 during week 3 or 4.

Secondary Outcomes (10)

• Health-Related Fitness Assessments

  The health-related fitness assessments were performed during study Visit 2 during week 2.

• Health-Related Fitness Assessments

  The health-related fitness assessments were performed during study Visit 2 during week 2.

• Health-Related Fitness Assessments

  The health-related fitness assessments were performed during study Visit 2 during week 2.

• Health-Related Fitness Assessments

  The health-related fitness assessments were performed during study Visit 2 during week 2.

• Anthropometrics

  Anthropometrics were measured during Visit 3 or 4 during the GEST Visit during week 3 or 4.

Study Arms (2)

GEST Visit

EXPERIMENTAL

As described in the detailed study description, the GEST Visit included measures of cardiovascular health at Hartford Hospital. These measures included BMI, waist circumference, exhaled carbon monoxide (CO), vascular health (i.e., carotid intimal medial thickness and arterial stiffness), HRV, resting BP, the GEST, and blood draws pre- and post-GEST to obtain SCD and CVD biomarkers.

Behavioral: GEST

CONTROL Visit

NO INTERVENTION

On either Visit 3 or 4, subjects performed the CONTROL Visit. Resting auscultatory blood pressure was measured according to AHA standards. At the conclusion of CONTROL, subjects were fitted for the ABP monitor. Subjects were instructed to proceed with normal activities, not to exercise, and to keep their arm still and extended at their side when each ABP measurement was being taken. Subjects carried a standard journal, recording activities performed during each measurement, any unusual physical or emotional events, and sleep and wake times. The following morning, subjects detached the monitor and returned it that day to the study investigators.

Interventions

GEST BEHAVIORAL

On either Visit 3 or 4, subjects performed a maximal cardiopulmonary GEST following the Balke protocol. Immediately prior to the GEST, the study physician or his designee performed a brief physical examination, in which BP was assessed and all relevant medical information (i.e. medical history, medications, family history) were reviewed. The physician who completed the physical examination remained present during the GEST to monitor the subjects' electrocardiogram (ECG) and other physical signs. After the GEST was completed, the study physician reviewed the ECG for signs of ischemia. Breath-by-breath analysis of expired gases (i.e. oxygen and carbon dioxide) (ParvoMedicsTruneOne® 2400 Metabolic Measurement System, ParvoMedics Inc., Sandy, UT) determined maximal oxygen uptake (VO2max). Heart rate was measured continuously with a 12-lead ECG system and BP was measured by auscultation every 3 minutes during the GEST.

GEST Visit

Eligibility Criteria

• Age: 21 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Subjects had to be full active duty firefighters employed by the local fire department in central Connecticut (CT).
• Subjects confirmed that they were taking the same medication for four weeks prior to Visit 1 and continued taking that medication throughout the duration of the study.

You may not qualify if:

• Subjects were excluded from the study if they were not able to comply with all study procedures as described in Visit 1, or in the event of injury or illness that would not enable them to participate.
• If subjects had resting blood pressure readings that were \> 160 for systolic blood pressure and/or ≥ 100 mmHg for diastolic blood pressure, they were excluded from the study and referred to their primary care physician for follow up.
• Subjects that were excluded from the study were not penalized in any way by the researchers or the administrators of the local fire department.

Sponsors & Collaborators

• University of Connecticut: lead
• Hartford Hospital: collaborator

Study Sites (1)

Hartford Hospital

Hartford, Connecticut, 06106, United States

Location

MeSH Terms

Conditions

Cardiovascular Diseases; Post-Exercise Hypotension

Condition Hierarchy (Ancestors)

Orthostatic Intolerance; Primary Dysautonomias; Autonomic Nervous System Diseases; Nervous System Diseases; Hypotension; Vascular Diseases

Study Officials

• Linda S Pescatello, PhD

  University of Connecticut

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: HEALTH SERVICES RESEARCH
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: August 6, 2020
• First Posted: August 14, 2020
• Study Start: April 1, 2015
• Primary Completion: January 1, 2016
• Study Completion: January 1, 2016
• Last Updated: August 14, 2020

Record last verified: 2020-08

Locations

US (1)