Fighting Fires and Heart Disease
On a muggy Texas summer morning, Dr. Matt McAllister found himself in full firefighter gear, hauling hoses and dragging a 160-pound dummy across the pavement of a Lake Travis Fire and Rescue parking lot. This may not be the typical scene that comes to mind when picturing an assistant professor at a university, but for McAllister this is just another day in the life of a researcher investigating the effect of a dietary intervention on firefighters’ physical health.
McAllister brought his interest in firefighters with him when he joined the Health and Human Performance (HHP) department in fall 2018. When he was a Ph.D. student at Mississippi State University, he worked with Dr. Heather Webb, whose research introduced him to the fact that firefighters have the highest occupational risk of death from heart attack or stroke. As a student of exercise science and nutrition, McAllister was immediately interested in what physical and dietary interventions had been tested in the firefighter population and was shocked to find that very few exercise interventions and not a single dietary intervention had been studied.
Firefighters’ predisposition to heart disease boils down to oxidative stress. Oxidative stress is a specific type of stress that results from excessive production of free radicals in the body. Free radicals have unpaired electrons and frantically search the body for an electron to pair with, which causes cellular damage that can elevate the risk of heart disease. Common causes of oxidative stress include heat, psychological stress, and disruptive sleep; in other words, an ordinary day for a firefighter.
Determined to find an effective intervention to lower this risk, McAllister is setting out to publish the first study on how dietary change may impact free radical damage in the bodies of firefighters. Specifically, he is studying firefighters who participate in an eight-week time-restricted feeding protocol that asks participants to eat all their calories for the day within a 10-hour period and fast for the remaining 14 hours. According to McAllister, just like human brains keep internal clocks that tell the body when to wake and when to sleep, human livers keep clocks that respond to food intake. When the liver clock is disrupted, levels of fat and cholesterol increase along with blood pressure. While no researcher has yet published a study on this intervention in firefighters, McAllister says there is some evidence that it may be the perfect diet for firefighters, who are often disrupted by shift work. Time-restricted feeding will help to regulate their liver clocks, which will increase the enzymes in their bodies that help to burn fat and decrease inflammation. This diet is also relatively easy for firefighters to implement, as it doesn’t ask them to change the amount or type of food they eat, only the period during which they eat it. In order to control for individualized exercise regimens, McAllister has divided participants into two groups. Over eight weeks, both will participate in a full body training program specifically created for this study, but only one group will complete the diet. Before and after this eightweek period, McAllister and his students will measure several biological factors such as muscular strength, body fat percentage, inflammatory markers and firefighters’ physical performance, which is where the Lake Travis Fire & Rescue parking lot comes into the story.
"If you follow this diet program and you can come out [of the fire grounds test] with a couple extra minutes of air, that would be a couple extra minutes of air that might save someone's life"
-Dr. Matt McAllister, Assistant Professor
McAllister’s partnership with Lake Travis Fire & Rescue developed through his HHP colleague, Stacey Herzog Bender, whose husband, Zach, is a firefighter in Lake Travis. McAllister presented the idea to Fire Chief Steve Knaus and firefighter Matt Benson, who is a station engineer and serves as the department’s health and wellness coordinator. The pair were interested in the potential partnership and brought it to the attention of Fire Chief Robert Abbott, who quickly saw that the research would come with myriad benefits for the firefighters and supported the project. With everyone’s approval, McAllister set off to begin his research, which started with three days of rigorous pre-testing prior to the eight weeks of exercise and dietary intervention.
On day one, firefighters were equipped with full gear and oxygen tanks and asked to complete what McAllister calls the fire grounds test, which is a demanding course that involves a series of physical challenges that would be required of them in the field, such as hose dragging, ladder carrying, forced entry tasks, victim removal, and ceiling breaching. In an act of solidarity, McAllister completed this test alongside the firefighters and finished in an impressive 10 minutes (the average time to completion for the firefighters was 9 minutes). During the test, McAllister’s students measured air depletion, time to completion and heart rate. They also collected saliva that will later be tested for inflammatory and stress markers.
Day two was comprised of muscular strength and endurance testing such as bench presses, squats, pushups, inverted rows and vertical jumps, and on day three firefighters participated in a graded excess treadmill test. In this test participants began by running on a treadmill at a low intensity and students gradually increased the intensity every three minutes so that the firefighters would become completely exhausted over the course of 15 minutes. The purpose of this test is to measure the maximal rate of their oxygen consumption, or VO2 max. McAllister points out that this is an important marker for his team to examine, as increasing the amount of oxygen one can consume per minute is correlated with lower risk of heart disease. On the third day, the team also measured body fat and collected blood to measure hormones, inflammatory markers and markers of free radical damage.
While McAllister is still in the data collection phase of his project, he is excited not only to see the results of the study, but also for the hands-on experience his students are getting. His Metabolic and Applied Physiology Lab is staffed by one funded graduate assistant and ten undergraduate and graduate students who receive training through his various research projects. In this study, his students experience a range of research activities from basic data collection, such as measuring height and weight to administering finger pricks to measure levels of lactate and glucose in the blood. Other students in his lab are trained to handle blood after it has been drawn and are able to centrifuge it and extract the plasma for analysis.
McAllister’s hope is that the study will be the first step in developing a physical training and diet program for firefighters that will help not only to save their lives, but the lives of others as well. Putting the study into perspective, he suggests, “if you follow this diet program and you can come out [of the fire grounds test] with a couple extra minutes of air, that would be a couple extra minutes of air that might save someone’s life.” •