The Influence of Cardiorespiratory Fitness on Firefighter Cardiovascular Health Under Conditions of Heavy Physical Exertion
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 21
- 试验地点
- 2
- 主要终点
- Change in Ambulatory Blood Pressure (ABP)
研究概览
简要总结
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.
详细描述
The primary purpose of this study was to examine the influence of cardiorespiratory fitness on the acute release of SCD biomarkers and other cardiovascular disease (CVD) risk factors at rest and in response to a bout of maximal physical exertion among 21 firefighters from a local fire department in Connecticut. The study investigators hypothesized that firefighters that are aerobically fit will have lower levels of biomarkers of SCD and a more favorable CVD risk factor profile at rest and in response to a maximal physical effort than firefighters that are not aerobically fit.
FIT and FIRED UP is based on the theoretical foundation of the health belief and social cognitive models of health behavior change which have been shown effective in improving diet and exercise behaviors in firefighters. Specifically, the investigators sought to identify job-specific risk factors for SCD and CVD in firefighters in order to better tailor an intervention that focuses on providing information, reducing barriers to changing unhealthy behaviors, reducing stress, and increasing firefighter efficacy to engage in healthier behaviors.
All eligible members of the fire department were invited to participate in the study. Visit 1 included an orientation health education session at the fire department in which the study investigators delivered a lecture on physical activity and "heart healthy" habits. Interested subjects were able to review the informed consent and questionnaires.
Subjects completed and signed the informed consent at the beginning of Visit 2. This visit consisted of 4 health-related fitness assessments, including sit-up, push-up, flexibility and handgrip tests. Visits 3 and 4 consisted of measures of cardiovascular health at Hartford Hospital and the control visit. The cardiovascular health measures included body mass index (BMI), waist circumference, exhaled carbon monoxide (CO), vascular health (i.e., carotid intimal medial thickness and arterial stiffness), heart rate variability (HRV), resting BP, the maximum graded cardiopulmonary exercise stress test (GEST), and blood draws pre- and post-GEST to obtain SCD and CVD biomarkers. Firefighters were then attached to an ambulatory blood pressure (ABP) monitor and heart rate monitor for 24hr to assess ambulatory BP and HRV, respectively. Of note is that Visits 3 and 4 were conducted in random order so that study investigators could isolate the influence of the GEST on the ambulatory BP response to exercise from the control rest day. Randomization was performed using www.randomization.com. The control visit included measures of resting and ambulatory BP. In addition, subjects completed paper and pencil questionnaires on the topics of physical activity, nutrition, sleep, and mental health at this visit.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Health Services Research
- 盲法
- None
入排标准
- 年龄范围
- 21 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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.
排除标准
- •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.
结局指标
主要结局
Change in Ambulatory Blood Pressure (ABP)
时间窗: ABP was measured at the conclusion of Visits 3 and 4 during weeks 3 and 4.
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.
Change in Resting Blood Pressure
时间窗: Resting BP was measured during Visits 3 and 4 during weeks 3 and 4.
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.
Dietary Intake
时间窗: The questionnaire was filled out during Visit 3 or 4 at the Control Visit during week 3 or 4.
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.
Peak Oxygen Consumption
时间窗: The GEST took place either during Visit 3 or 4 during week 3 or 4.
VO2peak was measured by the maximal graded exercise stress test (GEST). The VO2peak test is the gold standard measure of cardiorespiratory fitness.
Change in Fasted Blood Sampling
时间窗: The blood sampling occurred at Visit 3 or 4 during the GEST Visit during week 3 or 4.
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.
次要结局
- Carotid-Intima Media Thickness (cIMT)(CIMT was measured during Visit 3 or 4 during the GEST Visit during week 3 or 4.)
- Change in Arterial Stiffness Assessment(Arterial stiffness was measured during Visit 3 or 4 during the GEST Visit during week 3 or 4.)
- Change in Resting Heart Rate Variability (HRV)(Resting HRV was measured during Visit 3 or 4 during the GEST Visit during week 3 or 4.)
- Change in Ambulatory HRV(Ambulatory HRV was measured during Visit 3 or 4 during the GEST Visit during week 3 or 4.)
- 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.)
研究者
Linda Pescatello
Professor
University of Connecticut