Is One Type of Cardio Better Than Another? Short answer: It Depends. 

By: John Hofman MS., CSCS*D, TSAC-F*D

There is no question that exercise is needed in the fire service. It is a great way to maintain a healthy weight, curb cravings, promote good blood sugar levels, keep your mind sharp and support your entire cardiovascular system. 

But the type of cardiovascular exercise has been the latest argument. Should you be performing low-moderate intensity workouts or high-intensity workouts? There’s no question that as exercise and activity levels increase, cardiovascular risk decreases. The key is to do it on a regular and consistent basis.

So many fitness professionals will debate the importance of one over the other, but realistically they’re both valuable tools. Which is more important will depend on the goal of the firefighter. One specific goal of all firefighters is their maximal oxygen uptake (peak VO2).

Based on the recommendations of the IAFF/IAFC Wellness Fitness Initiative, firefighters should have a peak VO2 of no less than 42 ml·kg−1·min−1 to meet the job’s physical demands. Those who have a peak VO2 of 33.5 ml·kg⁻¹·min⁻¹ or less have been determined to be at risk because they can only perform specific firefighter tasks for a few minutes (1). Coronary heart disease is the leading cause of death within the fire service, and those with a low aerobic capacity increase their chances of having a myocardial infarction by 90% (3). So the overall goal should be to improve the firefighter’s aerobic capacity to a safe and effective level. 

Weight loss is a goal of many firefighters

High-intensity training will primarily focus on caloric quantity by promoting weight loss by exercising hard and maximizing our total caloric expenditure. On the other side, a long slow run will focus on caloric quality and what type of fuel is being burned. Our diet is the best method for overall weight loss, but it also helps determine what type of energy to burn. The correct training stimulus can determine what type of fuel we use during exercise and rest (4). High-intensity training will burn carbohydrates and create adaptations that will improve your glycolytic capabilities, while also improving your ability to tolerate lactate and efficiently convert it back to a usable form of energy.  However, for endurance athletes energy coming from fat (low intensity) spares the glycogen and saves unwanted muscle breakdown, helping them finish the race. 

Fire suppression does utilize both aerobic and anaerobic energy systems. Let’s look at a typical structure fire: the first few minutes are sizing up the scene, pulling hose, and preparing to ventilate. Once the command has been given, a fire attack is established and eventually extinguished. A normal Self Contained Breathing Apparatus (SCBA) will last about 20 minutes during this entire process followed by rehab. This scenario would be considered high-intensity. However the job is not completed and there is still overhaul, cleaning, and other specific tasks required which could be classified as low intensity. Sometimes during this scenario, the firefighter will have a crossover point or ventilator threshold (VT). This is where the body switches its primary fuel from fat to carbohydrates. The goal of any firefighter program is to push the VT (caloric quantity) into higher intensities (caloric quality) and optimize aerobic efficiency.  

Low-intensity training and its value for firefighters

When performing low-intensity training the challenge will be focused on inspiration because there is less CO2 produced in fat catabolism versus carbohydrate catabolism. This is why you are able to talk during a long slow run (ie. talk test). By improving on your aerobic system the firefighter will be able to improve their overall work capacity. High-intensity workouts will develop both inspiration and expiration of the firefighter because of the given amount of CO2 produced and O2 used. The body wants to remove the CO2 by expiring forcefully and rapidly. As the intensity is increased, so does the lactate production, requiring more buffering, which produces more CO2. When the anaerobic system improves the firefighter will be able to continue to work and high intensity for a longer period of time.

So is there an optimal type of training for firefighters?

Because most firefighters are pressed for time during their shift a short high-intensity intermittent training program would be appropriate. Based on science, we know aerobic training improves maximal aerobic power but does not change anaerobic capacity, but high-intensity intermittent training may improve both anaerobic and aerobic energy systems significantly, probably through imposing different intensities (5). In another study, high-intensity training was better at increasing aerobic capacity than moderate exercise (6). However, training at low-moderate intensity is still sufficient to reduce cardiovascular risk. One study found that only 1 out of 19 studies examined showed moderate-intensity exercise to be more effective than high-intensity when it came to decreasing cardiovascular health risk factors such as high blood pressure or cholesterol, blood sugar control or body weight (7). 

No conclusion has been made on the best prescription for cardiovascular disease. Some studies found that short, intense bursts were more effective, while others found that lower intensity for longer periods of time was better (8). Still, aerobic capacity is still widely regarded as a good measure of physical fitness and has been shown to be a good predictor of death due to cardiovascular problems. No matter which type or intensity of exercise the evidence deems the most effective, it will have no benefit unless the individual actually does it.

Plan of action

Identify the firefighter’s needs first before assuming one method is the best method for everyone. An older more experienced firefighter who is overweight and has a bad back may not be inclined to do hard intervals. So apply appropriate levels of exercise and progress them along.  Start them off with aerobic intervals, where specifically timed work intervals are followed by specific timed active recovery. By applying the appropriate strategy and solution you will help your firefighter achieve their goal which over time will create a healthier department. 

1. Tierney MT, Lenar D, Stanforth PR, Craig JN, Farrar RP. Prediction of aerobic capacity in firefighters using submaximal treadmill and stairmill protocols. J Strength Cond Res. 2010 Mar;24(3):757-64.
2. Peak, WF, Lundergan, L, and Johnson, JJ. Fitness self-perception and V̇o_2max in firefighters. J Occup Environ Med 44: 546-550, 2002.
3. Rita F. Fahy, Paul R. LeBlanc and Joseph L. Molis. Firefighter Fatalities in the United States 2010. June 2011
4. Melanson EL, MacLean PS, Hill JO. Exercise improves fat metabolism in muscle but does not increase 24-h fat oxidation. Exerc Sport Sci Rev. 2009 Apr;37(2):93-101.
5. Tabata, Izumi; Nishimura, Kouji,  Kouzaki, Motoki; Hirai, Yuusuke; Ogita, Futoshi; Miyachi, Motohiko; Yamamoto, Kaoru. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and ˙VO2max. Medicine & Science in Sports & Exercise: October 1996 – Volume 28 – Issue 10 – pp 1327-1330
6. Helgerud, J et al. Aerobic high-intensity intervals improve VO2 max more than moderate training. Med Sci Sports Exerc. 2007;39:665-71.
7. Houmard, JA et al. Effect of the volume and intensity of exercise training on insulin sensitivity. J Appl Physiol. 2004;96:101-6
8. Buchan, DS et al. The effects of time and intensity of exercise on novel and established markers of CVD in adolescent youth. Am J Hum Biol. 2011;23:517-2