The job of fighting fires is physically demanding. On arriving and assessing the situation, a firefighter may perform many tasks, including deploying and carrying a charged hose, climbing stairs, carrying victims, and performing ladder work. The added temperature from the fire increases the risk of overheating. The intensity of the work increases the heart rate substantially, putting undue stress on the heart. For a poorly conditioned individual, such exertion can be life-threatening.

Physical fitness programs can improve the firefighter`s overall conditioning. A suitable program will improve on-the-job performance and reduce on-the-job injuries. A common problem with typical conditioning programs is a lack of aerobic activities. When aerobic conditioning is performed, the intensity is often higher than the necessary level for the individual. The exercise prescription should take into account the individual`s age and present conditioning level. Without acknowledging these factors, a participant risks injury or illness.

Assessment of the appropriate output is based on the individual`s capacity to handle work. This ultimately gets down to the heart rate. Two types of training should be considered when setting up an exercise program–aerobic, which means ~~~~”with oxygen” and anaerobic, which means “without oxygen” or, more accurately, “limited oxygen.”

Why is oxygen an important element in a fitness program? The oxygen availability determines how long you can perform at a certain intensity; and often this means longer endurance on the job. It determines how much body fat you can use as fuel. Let`s look at how this all comes together.


Fat is an inefficient fuel for the body. The amount of fat your body has is affected by genetics and diet. At birth you have a given number of fat cells. If you do not eat a balanced diet for your genetics, you can enlarge the fat cell size. You do not remove the cells with exercise, you shrink them. The smaller the fat cells the less space it takes up in the body, and the more efficient you can be. Fat delays the blood flow to the working muscles, since the blood has to move around and about and then through the fat cells. Your goal is to shrink size of the fat cells. You can do this through aerobic exercise done in the correct heart-rate zone. Examples of this type of exercise are walking, jogging, running, bicycling, cross-country skiing, treadmill walking or running, and stair climbing. The appropriate zone for optimum fat burning uses the individual`s age and conditioning level as parameters. The percentage used to determine the exercise intensity is between 60 and 70 percent. Follow Karvonen`s Formula to calculate your zone as shown in Figure 1.

This guideline is based on your present age and conditioning level. As these parameters change so will your zones. The more efficient a fat burner you become, the lower your zones will be, and the more work it will take to get your body into the zone. Once you are in the zone, you will be able to stay there longer, consequently burning more total calories. If you exceed the zone, you will be able to endure longer at that output since you are blending fat and glycogen fuels.


To figure your heart rate zone, you need to find your resting heart rate first. Otherwise, you can use the average of 72 beats per minute. To obtain your true resting heart rate, try to pick three mornings on which you wake up without an alarm, if possible. Place your watch by the bed the night before.

When you awaken, reach for the watch before you get out of bed. Count your heart beats for a full minute and make a note of it. Be sure to count every beat, as some may be a little faint in the morning. Do this for three mornings and then average the results. This will be your true resting heart rate. It is a measure of how well-rested, dehydrated, and refueled you are.

This number can tell you quite a bit. If you are highly conditioned or a good fat burner, it will be low (40s to 50s).

It will tell you if you are recovered. If one morning you get up and it is three to five beats higher than normal, do not exercise that day. Eat and drink water to get back to your regular value.

The elevated heart rate might indicate that your body is fighting an infection, a possible injury, or fatigue and dehydration carried over from a busy shift. In addition, if you lifted hard one day, your body will experience little microtears in the muscles. If you do not eat enough to replenish the muscle, the body experiences a depletion–often indicated by soreness the next day.

Respecting the resting heart rate will reduce your chance of getting sick or injured. If you do not listen to this messenger you may lose seven to 10 days in recovering the body from a sickness or injury. As firefighters, you need to be aware of this possibility. If, after a busy shift, you fail to rest, hydrate, and feed, you will end up fatigued and sore. This may be compounded if you work a second job that is also physically demanding.

Once you have your resting value, proceed with the formula. The resulting number, after subtracting the age and resting heart rate, is multiplied by 60 percent and 70 percent. The resting heart rate is added to these numbers to get the two numbers for optimum fat burning. Your goal in the beginning will be to exercise as many minutes between these two values as possible to train the body to become a fat burner.

Using a Polar Heart Rate Monitor is one way to properly assess your heart`s response to the exercise. Using a heart rate monitor will allow you to adjust your workload quickly if your rate gets too high or too low, since it provides you with an auditory and visual response. It also alerts you to dehydration due to a bloodflow volume change being experienced at the heart. Your heart rate will climb seven to 10 beats without a change in the workload. Drink water while you exercise to avoid this response. If you are not on a monitor, take a 10-second count. The numbers to use as a guideline will be your zone numbers divided by six. It will probably be somewhere between 21 to 26 beats for the 10-second count.

After four to six weeks, you will notice a few things: hunger after you finish the exercise session, yet you will feel as though you didn`t do anything; your clothing will be getting too big in the waist area; hunger pains while exercising; and a need to urinate during the exercise session. Also, the intensity level necessary to stay in the zone will no longer be enough–you will be working harder at the same heart rate.

Once these phenomena have occurred, you can challenge the body with a variety of intensities and other activities so it will not get bored and stop providing you with results. This topic will be discussed in a future column.

CAROLINE SMITH, M.S. is president of SportSense Co., a Dallas-based consulting firm that works with individuals and groups on exercise and nutrition. She has a master of science degree in exercise physiology and bachelor`s degrees in psychology and nutrition. Smith also is wellness coordinator for the City of Richardson, Texas, where she created and implemented a physical fitness assessment and exercise prescription program for firefighters.

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