BY DEBORAH FEAIRHELLER
Hypertension is a global health problem. Defined as a resting blood pressure higher than 120/80 mmHg, recent statistics estimate that close to 80 million adults in the United States have high blood pressure. Treatment costs are close to $50 billion, and even with that, blood pressure awareness and control remain problems.1 Many people don’t even know they have hypertension, and many others cannot control their blood pressure despite daily medication. Surprisingly, the majority of the population does not even know what blood pressure is, what increases it, what causes it to change, or how much it can fluctuate throughout the day.
High blood pressure increases the risk of cardiovascular disease, kidney disease, and stroke.2,3 Blood pressure increases with age and with body weight. Blood pressure is the product of vascular resistance (compliance of the blood vessels) and cardiac output. Blood vessels are made of muscle and, much like our large muscles, they can become less pliable. Dynamic changes in the smooth muscle activity as well as alterations in molecular signal traffic through the blood vessels define how the blood vessel lining responds.4 This can lead to an increase in vascular resistance, and increased resistance stiffens the blood vessels. Consider old and worn-out fire hose; it stiffens with age. Blood vessels are similar; they age and become less pliable.
Cardiac output is the total amount of blood that the heart can pump in one minute. This is directly related to heart rate and the volume of blood the heart ejects with each beat (stroke volume). Heart rate is controlled by many physiologic variables, but sympathetic activity is a major contributor. As firefighters, when we feel the rush of adrenaline when the pager goes off, we are actually feeling an increase in sympathetic nervous system activity. Sometimes, we can even feel our heart rate increase. This stress and excitement also increase blood pressure. It’s these instantaneous increases in blood pressure combined with a reduced flexibility of blood vessels that may make firefighters prone to cardiac incidents.
Firefighter Study
Recently, my laboratory measured blood pressure increases from certain amounts of stress in volunteer firefighters under different clothing conditions. In the study, the stress was a “controlled” stress of a treadmill test. Exercise stress on a treadmill is not a true simulation of actual firefighting work, but research needs to start somewhere. Research needs to elucidate exactly how high the blood pressure can and will go when firefighters are under the stress of fireground operations. The enthusiasm toward participation in the study proved how important heart health is to the fire service. It also showed how many firefighters are unaware of their true blood pressure levels.
The study design was simple: Firefighters completed two treadmill tests-one in regular clothing and one in full turnout gear with self-contained breathing apparatus (SCBA) while breathing air. Naturally, blood pressure increases with physical activity. So, as expected, blood pressure increased when the firefighters were on the treadmill in regular clothing and, as expected, the blood pressure increase was exaggerated when the firefighters were on the treadmill in full gear. The normal systolic BP increase for men at maximal stage of Bruce Protocol is about 50 mmHg above resting levels.5 In our study, when participants wore full firefighting gear, the systolic blood pressure increased from its resting level to a maximum level that was almost twice the increase expected during maximal effort.6 The blood pressure difference from rest to maximal levels averaged 87 mmHg, and this occurred within seven minutes. This is a very short time for blood pressure to reach these maximal levels. As firefighters, we work in extremely stressful environments while wearing thickly insulated and heavy clothing. We know that our heart rate and blood pressure increase while we are on a scene and active. But if we want to begin to prevent cardiac incidents, the relationship between how high the blood pressure can go, how quickly it gets there, and how this relates to the type of work we are doing needs to be understood.
The study also found that the blood pressure levels remained elevated in the firefighters after they had done the test in their full gear. Some firefighters’ blood pressure didn’t return to baseline levels for 12 minutes after exercise on the treadmill. Keep in mind that the treadmill test is a stress test but it is not as stressful as true fire and rescue operations. This emphasized the importance of taking breaks and participating in rehabilitation during fire operations. Many times on the fireground, crew members do not go to rehab to sit and rest. Perhaps this is another reason many cardiac incidents occur. Firefighters who are prone to cardiac incidents or who may have undiagnosed underlying cardiovascular disease need established breaks to allow blood pressure levels to return to normal.
Think about it: A firefighter does not stop working, cleans up at the scene, returns to the fire station, cleans up the tools, repacks hose, and washes down equipment. Many times, firefighters work continually for long periods and then go right home, never taking a break at all. Without proper recovery, firefighters prone to high blood pressure or at risk for cardiovascular disease are very likely a setup for a cardiac incident when they go home.
Improving Blood Pressure
So, the question becomes, what can improve blood pressure? Increased physical activity, improved diet, and stress management can all improve blood pressure.7 Many years of clinical research have shown that aerobic exercise improves blood pressure. Increasing physical activity even a little bit can improve the health of blood vessels. Just imagine if the old and worn-out fire hose could be rejuvenated! Research has proven that exercise can lead to around a 10 mmHg reduction in systolic blood pressure, and aerobic exercise can be as simple as going out for a good brisk walk.8 Any type of aerobic activity increases the amount of blood that the heart ejects with each beat. More importantly, though, is that exercise can also improve blood vessel function. This means that blood vessels actually become more pliable, or flexible, and allow blood to flow more easily. Therefore, when firefighters are in the middle of periods of high stress (like during fire operations), those with healthier blood vessels and a lower blood pressure will respond better, their heart is healthier, and they are less likely to have a cardiac incident. Exercise can do this. It will improve blood vessel health, reduce blood pressure, improve heart health, and help lower body weight.
As firefighters, we can spend considerable time on call, and we may not always feel like we have the time to get in a workout. No time is one of the top reasons cited by Americans for not exercising. Also, as firefighters, we may not like to do traditional exercise. We may not want to go for a ride on the bike, work out on the treadmill, or go for a jog. Many fitness programs specific to firefighters are available that provide information on health, wellness, and fitness, including those offered by the National Fallen Firefighters Foundation, International Association of Fire Fighters, National Interagency Fire Center FireFit program, and Firefighter Fitness Online. Some of these programs even suggest exercises that involve fireground tools or ladders. They are very functional for those who don’t like to get on the treadmill. My lab is going to begin to investigate what types of exercise or activity can most effectively lower blood pressure levels in firefighters.
Increasing awareness of firefighter blood pressure levels is imperative. Knowing what type of exercise can help lower resting blood pressure will be a significant finding. More importantly, though, knowing how much blood pressure actually elevates while they are doing firefighting activities will be a valuable step in the process of understanding how we can improve firefighters’ heart health. But, perhaps a key to all of this is for firefighters to know how it feels when their blood pressure goes that high and to be aware that they need immediate rest and rehabilitation.
Understanding firefighters’ blood pressure responses to work is a valuable first step in improving our cardiac health. Some firefighters know what their blood pressure is; some are aware of their heart health; and, interestingly, others don’t consider it. Let’s spread the word! Begin to talk about blood pressure with your peers, and begin to encourage increased physical activity in your crew. Concern for blood pressure and awareness of how firefighting activity affects blood pressure are the first steps to heart health.
Acknowledgment: Thanks to the following Pennsylvania volunteer firefighters for their participation in the first research study: Collegeville, Trappe, Upper Frederick, and Lower Providence fire stations in Montgomery County; Reading fire station in Berks County; and East Brandywine, Thorndale, and Oxford fire stations in Chester County.
Endnotes
1. Go AS, D Mozaffarian, VL Roger, EJ Benjamin, JD Berry, MJ Blaha, et al. “Heart disease and stroke statistics- 2014 update: a report from the American Heart Association,” Circulation 2014; 129(3): e28-e292.
2. Williams MA, JL Fleg, PA Ades, BR Chaitman, NH Miller, SM Mohiuddin, IS Ockene, CB Taylor, and NK Wenger. “Secondary prevention of coronary heart disease in the elderly (with emphasis on patients > or =75 years of age): an American Heart Association scientific statement from the Council on Clinical Cardiology Subcommittee on Exercise, Cardiac Rehabilitation, and Prevention,” Circulation 2002; 105:1735-1743.
3. Chobanian AV, GL Bakris, HR Black, WC Cushman, LA Green, JL Izzo Jr, DW Jones, BJ Materson, S Oparil, JT Wright Jr., and E J Roccella. “The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report.” JAMA 2003; 289: 2560-2572.
4. Feletou M, PM Vanhoutte. “Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture).” Am J Physiol Heart Circ Physiol 2006; 291(3): H985-1002.
5. Sharman JE, A LaGerche. “Exercise blood pressure: clinical relevance and correct measurement.” Journal of Human Hypertension 2014: 1-8. doi:10.1038/jhh.2014.84.
6. Feairheller DL. “Blood pressure and heart rate responses in volunteer firefighters while wearing personal protective equipment.” Blood Pressure Monitoring 2015; 20(4): 194-198.
7. Pescatello LS, BA Franklin, R Fagard, WB Farquhar, GA Kelley, CA Ray. “American College of Sports Medicine position stand. Exercise and hypertension.” Med Sci Sports Exerc. Mar 2004; 36(3):533-553.
8. Cornelissen VA, NA Smart. “Exercise training for blood pressure: A systematic review and meta-analysis.” J Am Heart Assoc 2014; 2: e004473.
DEBORAH FEAIRHELLER, PhD, is a firefighter with East Brandywine Fire Company in Chester County (PA) and Collegeville Fire Company in Montgomery County (PA). She is an assistant professor in the Health & Exercise Physiology Department at Ursinus College in Collegeville. Her research lab, the HEART (Hypertension & Endothelial function with Aerobic & Resistance Training) lab, examines the effect of lifestyle modifications on hypertension, ambulatory blood pressure, and vascular structure and function. As a firefighter, she has a vested interest in getting the fire service physically active and improving cardiac health.
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