Strength alone won’t protect firefighters from cardiac strain, but the right aerobic training and nutrition will
Cardiovascular disease has been the leading cause of on-duty firefighter deaths for more than two decades. Not building collapses, not burns, not traumatic injuries.1 Heart attacks. Year after year. Accounting for nearly half of all line-of-duty deaths.
Here’s what most people get wrong about that number: they assume it’s happening to the guy with the worst habits. The one skipping the gym, living on fried food and energy drinks, treating every shift dinner like a cheat meal.
But read through NIOSH firefighter fatality investigation reports and a different picture emerges. Experienced firefighters. Active on the job. No prior symptoms anybody recognized. Cardiac events on working fires.2 The pattern repeats across departments, across age groups, across body types.
Muscle Hides the Real Risk
Strength and cardiovascular health are related, but they are not the same system. A firefighter can have impressive upper body strength, carry his body weight easily, pass any functional test on the floor, and still have arteries silently narrowing toward a cardiac event.
Atherosclerosis is the buildup of plaque inside arterial walls, and it can progress silently for years. Decades, sometimes. The arteries narrow. The heart compensates. The body adapts. Until the demand of a working fire exceeds what the narrowed coronaries can supply, and the system fails.
Visceral fat compounds this. A firefighter can carry significant fat stored around his organs, metabolically active, chronically inflammatory, and directly correlated with accelerated coronary artery disease, and look completely normal in turnout gear.3 Body weight tells you almost nothing about that. BMI tells you slightly more and still misses most of what matters.
A firefighter who has spent years building his chest and arms while skipping aerobic work may look the part of someone who can handle the job physically. He probably can handle a lot of it. But strength doesn’t lower resting blood pressure. It doesn’t improve coronary artery compliance. It doesn’t reduce chronic inflammation. Those adaptations come from cardiorespiratory training, and looking muscular in the mirror is not evidence that you’ve done it.
Every Working Fire Is a Cardiac Stress Test
A clinical cardiac stress test elevates your heart rate to a controlled threshold and watches what happens. The goal is to uncover coronary insufficiency, the cases where the heart is fine at rest but can’t get enough blood supply when demand spikes.
A working structure fire does the same thing, except the threshold isn’t controlled, there’s no cardiologist monitoring, and the test ends when the fire ends. Not when your heart says stop.
Fireground tasks push oxygen uptake to 63 to 97% of maximum during active suppression, with heart rates climbing to 84 to 100% of max.4 PPE and SCBA drop aerobic capacity by 12 to 17% before the first hose length is pulled.5 Thermal stress, adrenaline, and accumulated physical work layer on top across the duration of the incident.
For a firefighter with undetected coronary disease, that’s not a fire. That’s a provoked cardiac event waiting for the right conditions.
The firefighter who looks fit but has never built a real aerobic base enters that environment with almost no reserve. Every task is near-maximal effort. Every task burns through oxygen faster. The heart works harder than it should to deliver blood through vessels that may already be compromised, and nobody suspected a thing because he looked fine.
What You Can Actually Do About It
The problem is real. But there are things we can do to prevent it.
Get Your Numbers Checked, Not Just Your Body Weight
A scale tells you your mass. It tells you nothing about your lipid panel, your inflammatory markers, or whether you have subclinical coronary artery disease. Get a basic metabolic panel and lipid panel annually. Know your LDL, HDL, triglycerides, and C-reactive protein, a marker of systemic inflammation directly associated with cardiovascular risk. Some departments provide these annual screenings through outside agencies. If yours doesn’t, that’s worth pushing for. Know what’s happening inside your body before it becomes a problem you can’t fix.
Train Your Aerobic Engine, Not Just Your Aesthetic
Consistent moderate-intensity aerobic work, 70 to 80% of max heart rate, three to four sessions per week, builds the base that protects your heart. Running, rucking, rowing. This is the training that grows stroke volume, improves coronary artery function, and lowers resting heart rate. Add intervals one to two days per week. Not instead of steady-state work, in addition to it.
The target is a VO2 max well above 42 ml·kg−1·min−1.6 VO2 max is simply a measure of how efficiently your body uses oxygen during hard effort. The higher the number, the more reserve your heart has when the work gets heavy. You don’t need a lab to get a rough estimate. The 1.5 mile test is the most straightforward option: run or walk 1.5 miles (2.4 km) as fast as you can and record your time. You can do it outside or on a treadmill. Plug your time into any free online VO2 max calculator and you’ll get a usable number. If your knees won’t cooperate, a 2,000-meter rowing test or a 12-minute cycling test on a stationary bike work the same way. The goal isn’t a perfect score. It’s a baseline you can track and improve.
Track Your Resting Heart Rate
Resting heart rate is one of the most accessible and overlooked indicators of cardiovascular fitness. A lower resting heart rate means greater stroke volume, better cardiac efficiency, and stronger parasympathetic function. Those are the exact adaptations that protect you when the work gets hard. Check it first thing in the morning before you get out of bed. A watch with a heart rate monitor makes it automatic, or you can place two fingers on the inside of your wrist, count the beats for 30 seconds, and double it. Track it over weeks and months. If it’s trending down, your training is working. If it’s suddenly 7 to 10 beats above your normal, take that seriously and back off until you understand why.
Clean Up What You Eat Between Calls
Most station nutrition is reasonable at shift dinner and terrible the rest of the time. Processed snacks, fast food on overnight calls, high-sugar drinks. That pattern chronically elevates insulin and inflammatory markers, directly feeding the process that puts plaque in coronary arteries. It doesn’t take an overhaul. Keep easy options around: boiled eggs, Greek yogurt, nuts, fruit, jerky, cottage cheese. Protein and fiber at every meal, even the small ones between calls. Small, consistent shifts in dietary quality across a career reduce cardiovascular risk in ways that no amount of gym work can fully compensate for.
You Can Get Ahead of This
The data has been consistent for more than 20 years. Cardiovascular disease kills more firefighters than anything else, and it doesn’t give much warning. It builds quietly behind a strong back and a clean bill of health at the last physical.
Most guys in this job will never think about their coronary arteries until something goes wrong. That’s understandable. But the research is clear, the risk is real, and the tools to reduce it are simple enough that there’s no good reason to wait.
Get your numbers. Build your engine. Eat like it matters. Know your resting heart rate. Take care of the body that takes care of everyone else.
References
- Fahy, R.F., LeBlanc, P.R., & Molis, J.L. (2023). Firefighter Fatalities in the United States – 2022. National Fire Protection Association.
- National Institute for Occupational Safety and Health. (2024). Fire Fighter Fatality Investigation and Prevention Program. Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/fire
- Baughman, P., et al. (2013). Central adiposity and subclinical cardiovascular disease in police officers. ISRN Obesity.
- Smith, D.L., et al. (1996). Cardiovascular, musculoskeletal, and metabolic responses to various firefighting activities. Ergonomics, 39(9), 1179–1186.
- Dreger, R.W., Jones, R.L., & Petersen, S.R. (2006). Effects of the self-contained breathing apparatus and fire protective clothing on maximal oxygen uptake. Ergonomics, 49(10), 911–920.
- Rhea, M.R., Alvar, B.A., & Gray, R. (2004). Physical fitness and job performance of firefighters. Journal of Strength and Conditioning Research, 18(2), 348–352.
Tyler Phillips is a fire captain with 15 years of service and the founder of Phillips Performance Systems, a fitness and nutrition coaching business built specifically for firefighters and first responders. He holds certifications as an NSCA Tactical Strength and Conditioning Facilitator (TSAC-F), NASM Certified Nutrition Coach (CNC), and Precision Nutrition Level 1 coach, alongside a doctorate in biblical studies. Tyler coaches firefighters on building the physical capacity to perform when it counts. Learn more at tylerphillips.org
