FITNESS AND BODY FAT: AN ISSUE OF PERFORMANCE
BY HENRY N. WILLIFORD, Ed.D., facsm, and Michele Scharff-Olson, Ph.D.
Over the past 20 years, there has been a great deal of controversy regarding the relationship between body fat, physical fitness, and firefighter performance. Because of the concern related to physical fitness, several organizations have developed guidelines or standards regarding physical fitness or performance. Although the controversy goes on as to what the minimal physical fitness or job-related standards should be, there are considerable research data that show the importance of physical fitness as it relates to firefighting.1-16
Several years ago, the Montgomery (AL) Fire Department, under the direction of Chiefs Wayne Grier, J. L. Fulmer, Ron Howard, J. W. McKee, and M. Jordan, initiated several studies to evaluate the health and performance status of Montgomery firefighters. They were concerned that if a firefighter became overly fat and had poor physical fitness, the firefighter would then be at a disadvantage in terms of performing duties on the fireground. Because of these concerns, several physical performance research studies were initiated to investigate the relationship between physical fitness and performance. The research projects were conducted in cooperation with the Human Performance Laboratory at Auburn University at Montgomery. The Human Performance Laboratory routinely conducts research related to health, fitness, and performance.
DOES ADDING WEIGHT AFFECT PERFORMANCE?
One study evaluated the effects of added weight on physical performance. The primary research question was, “Does adding extra weight or body fat affect performance?” The investigation found that adding additional weight while performing physical activity simulates the same physiological responses as carrying additional body fat.
The study results demonstrated what had been previously shown with different groups of athletes. (3, 12) Excess fat in terms of additional weight increases the energy cost of activity. A direct negative relationship was found between added weight and decreased performance. The greater the additional weight the person had to carry, the less efficient the person was in performing the aerobic or anaerobic activity. When extra weight is carried, the person is at an obvious disadvantage when performing prolonged strenuous weight-bearing physical activity. The added weight decreases performance and causes fatigue to occur at a faster rate. Carrying additional weight or fat produces an increase in exercise heart rate and blood pressure, a decrease in muscular endurance, an increase in cardiac demand, and a decrease in metabolic efficiency.
In addition, the extra weight can increase the potential for musculoskeletal injury. When competing in athletic events or firefighting, carrying additional weight has been shown to negatively affect performance. (3, 5, 11, 12) Being overly fat could prove to be dangerous for the firefighter and lead to injury and decreased job performance.
A recent investigation evaluating 88,000 Marine recruits found that recruits with a high body mass index (body weight in relation to height) and a 1.5 mile time of more than 12 minutes had a greater incidence of exertional heat-related injuries (ranging from dehydration to heat exhaustion and life-threatening heat stroke). (6) From 1988 to 1992, the Marine recruits experienced 528 cases of heat-related illness. The recruits with a high body mass index had an eightfold greater risk for developing exertional heat illness. Overweight individuals tend to produce a greater amount of heat during exercise and suffer from a reduction of the body`s ability to dissipate heat. (6)
One primary function of body fat is to store energy. Body fat is an excellent source of energy; however, one pound of fat is equal to approximately 3,500 kilocalories, or more than the required energy necessary to run a marathon. A 180-pound firefighter with 15 percent body fat would have approximately 94,500 kilocalories of storage fat (sufficient energy for approximately 32 days of fuel). Fat above optimal values adds extra weight that must be transported and is of little value from a physiological standpoint and can greatly decrease performance.
Table 1 on page 85 shows a summary of health and performance factors related to excess body fat. The research literature has clearly shown the adverse effects of being overly fat on both health and performance.
Table 2 on page 85 presents an example of the extra work required of a firefighter with a high percent of fat. Firefighter A weighs 180 pounds and has 15 percent body fat; Firefighter B weighs the same (180 pounds) but has 25 percent body fat. At 15 percent fat, Firefighter A has 27 pounds of fat and 153 pounds of lean body mass (lean body mass equals the weight of muscle, bone, and organs), whereas at 25 percent fat, Firefighter B has 45 pounds of fat and 135 pounds of lean body mass. Adding the weight of the mandatory equipment and SCBA (approximately 50 pounds), Firefighter A would have to perform while carrying a load of 77 pounds (fat plus equipment), whereas Firefighter B would be required to work with an additional 95 pounds. Firefighter B has 18 pounds less lean body mass and would have to carry an additional 18 pounds of weight. The additional 18 pounds of fat and less muscle mass for Firefighter B would put the firefighter at an obvious disadvantage from the aspects of performance, health, and safety.
SIMULATED JOB PERFORMANCE
In another project, we evaluated the relationship between a simulated job performance task and percent of body fat and lean body mass. (16) The research question was, “Is there a relationship between firefighter job-related performance and percent of body fat?” Approximately 100 firefighters were evaluated to determine their percent of body fat and their ability to perform a simulated job task. The job performance task consisted of a stair climb (carrying a 48-pound section of hose up five stories to the top of a drill tower), hoisting (hoisting a 36-pound hose from the ground to the top of the drill tower), forcible entry (using a nine-pound sledgehammer to move an I-beam five feet), hose advance (stretching a charged 112-inch hose 100 feet, and victim rescue (dragging a 175-pound manikin 100 feet).
Results of the investigation found a statistically significant relationship between percent of body fat and the time to perform the job tasks. As the firefighters` percent of fat increased, the time to perform the job tasks also increased. Results also found a negative relationship between lean body mass (muscle mass) and job-related performance. As the amount of muscle mass increased, the time to perform the job tasks decreased. The study concluded that percent of body fat and lean body mass were important predictors of job performance. Firefighters with greater fat-free weight and less fat tended to perform the simulated job tasks in less time.
In addition to the body fat data, we have additional data to show that muscle strength, endurance, and cardiovascular endurance are all related to job performance. Significant relationships were found between the number of pull-ups, pushups, 112-mile run time, and sit-ups and the simulated job task. The relationships indicate that cardiovascular fitness and muscular strength and endurance are also important predictors of job-related performance. (16)
MONTGOMERY FIRE DEPARTMENT PROGRAM
Considering the above data, the Montgomery (AL) Fire Department recently implemented a mandatory physical fitness program. Firefighters are screened monthly using height and weight standards. If the firefighter is over the height and weight standard, the firefighter can elect to be evaluated for percent of body fat. Firefighters who elect the percent of body fat option are evaluated in the Human Performance Laboratory. They are tested according to the hydrostatic or underwater weighting procedure to determine body composition (percent of body fat). The test determines the firefighter`s percent of body fat and lean body mass. Percent of body fat standards were established based on the firefighter`s age and sex. Individuals who are overly fat are given a period of time within which to meet the prescribed percent fat standards. Firefighters also exercise each duty day in a structured program to improve or maintain strength, endurance, flexibility, and cardiovascular fitness.
The Montgomery Fire Department is in the process of evaluating its physical fitness program. As a result of the physical fitness program, from 1995 to 1996, 328 personnel took the physical fitness test. The average fitness classification score increased 16 points. The mean 1995 score was 60 points (acceptable), and the mean 1996 score was 76 points (good). Firefighters were also required to perform a simulated job task annually. The mean time for the job task assessment was four minutes and 24 seconds.
Lack of physical fitness and performance puts the firefighter at an increased risk from the standpoints of both health and safety. The research data over the past 20 years clearly show the relationship between fitness, fatness, health, and job-related performance. For the Montgomery Fire Department, physical fitness and body composition standards were implemented as reasonable standards to promote the firefighters` health and safety and improve job performance. n
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HENRY N. WILLIFORD, Ed.D., FACSM, is a professor at Auburn University at Montgomery in Alabama and the director of the Auburn University Human Performance Laboratory. He conducts physiological research with the Montgomery (AL) Fire Department and has published more than 50 scientific articles related to health and performance. Williford was recognized as a Distinguished Research Professor in 1996.
MICHELE SCHARFF-OLSON, Ph.D., is an associate professor at Auburn University at Montgomery in Alabama and research administrator for the Auburn University Human Performance Laboratory. She is a faculty member for Reebok University and is recognized for her research related to physical performance and women. Olson has also published more than 50 scientific articles related to health and performance.