Physical Fitness and Cardiac Risk Factors of Professional Firefighters across the Career Span. (Research Note-Physiology)

Article excerpt

Key word: aging

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Firefighting can be a physically demanding occupation. Sothmann, Saupe, Jasenof, and Blaney (1992) found that during firefighting emergencies firefighters' heart rates were sustained at 88[+ or -]6% of maximum, which was estimated to be equivalent to 63[+ or -]14% of maximum oxygen uptake ([VO.sub.2]max). Gledhill and Jamnik (1992) measured oxygen uptakes averaging 41.5 ml * [kg.sup.-1]*[min.sup.-1] and peak lactate concentrations of 6-13.2 mM during demanding simulated firefighting tasks. Lusa, Louhevaara, Smolander, Kivimaki, and Korhonen (1993) reported relative aerobic strains from 41-101% of [VO.sub.2]max and relative mean heart rates between 66 and 90% of the maximum heart rate during simulated rescues in 110[degrees]C ambient temperatures, while firefighters wore fire-resistive clothing and a self-contained breathing apparatus. O'Connell, Thomas, Cady, and Karwasky (1986) found that stair climbing at 60 steps per minute in uniform while carrying firefighting equipment required heart rates of 84-100% an d oxygen consumptions 63-97% of maximum. Based on aerial ladder climb, victim rescue, hose drag, and ladder raise tests, Lemon and Hermiston (197Th) concluded that firefighting required approximately 60-80% of [VO.sub.2]max, even when other external stressors present at a fire were eliminated (i.e., heat, humidity, decreased [O.sub.2], increased [CO.sub.2], and emotional stress.)

Professional firefighters are generally selected on the basis of excellent physical fitness, firefighting experience, and likelihood of success with professional training. Cardiorespiratory fitness, muscular strength, muscular endurance, flexibility, and healthful body composition are important not only to meet occupational requirements but also for the safety of the firefighter, coworkers, and the public.

Because the physical demands of firefighting may remain high no matter what the professional firefighter's age (Lusa, Louhevaara, & Kinnunen, 1994), it is important that high levels of fitness be sustained across the career span. Physical fitness declines with age in the general population (Canadian Standardized Test of Fitness (CSTF) Operations Manual, 1987; Golding, Meyers, & Sinning, 1989; Kenney, Humphrey, & Bryant, 1995), and this has also been observed in firefighters (Barnard & Anthony, 1980; Kilbom, 1980; Lemon & Hermiston, 1977b; Saupe, Sothmann, & Jasenof, 1991). In contrast, the incidence of cardiac risk factors increases with age in both the general population (National Center for Health Statistics, 1994) and in firefighters (Barnard & Anthony, 1980; Saupe et al., 1991; Swank et al., 2000). Because of the additional occupational stressors and responsibilities inherent in firefighting, reduction of preventable coronary risk factors is desirable (Davis, Biersner, Barnard, & Schamadan, 1982) .The pur pose of this study was to describe age-related changes in physical fitness and the prevalence of major cardiac risk factors across the career span of professional firefighters and compare their incidence to those observed in the general population.

Method

Physical Fitness

Seventy-one male, professional municipal firefighters from the city of San Luis Obispo, California, participated in annual medical evaluations and physical fitness tests between 1983 and 2000, after providing informed consent. Measurements included: height (cm), weight (kg), blood pressure (mmHg), body composition (% fat), hand grip strength (kg), number of sit-ups and pushups, sit-and-reach score (cm), and aerobic capacity (ml[O.sub.2]*[kg.sup.-1]*[min.sup.-1]. Body composition was determined using hydrostatic densitometry (Franklin, Whaley, & Howley, 2000; Brozek, Grande, Anderson, & Keys, 1963), and skinfolds (Jackson & Pollock, 1985; Golding, Meyers, & Sinning, 1982). Sit-up scores were the maximum number of bent-leg sit-ups, from mat contact with the head, shoulders, and elbows to contact of the elbow with ipsilateral knee, completed in 60s. …