Physiological Demands

by NSCA's Essentials of Tactical Strength and Conditioning
July 2022


This excerpt briefly describes the different energy systems used by structural and wildland firefighters.

The following is an exclusive excerpt from the book NSCA's Essentials of Tactical Strength and Conditioning, published by Human Kinetics. All text and images provided by Human Kinetics.

When designing physical training programs, TSAC Facilitators must consider which energy systems are stressed during structural and wildland firefighting tasks. A comprehensive description of the typical job tasks for structural and wildland firefighters can be found in NFPA 1582: Standard on Comprehensive Occupational Medical Program for Fire Departments (81) and the NWCG’s Fitness and Work Capacity (110). Additional information may be sought for descriptions of job tasks for specialized teams (79, 80, 84).

Both structural and wildland firefighters perform a variety of tasks that stress all three energy systems. Table 17.1 summarizes several structural and wildland firefighter job tasks and the primary energy system that each task utilizes. Research regarding the cardiorespiratory demands of structural firefighting indicates that performing fireground tasks results in oxygen uptake levels that are 63% to 97% of maximum (122, 129, 132) and HR values between 84% and 100% of maximum (26, 122, 132). Not only are these physiological demands present during firefighting tasks, but HR and oxygen uptake may remain elevated for an extended period of time following work (often exceeding 30 minutes) (94), consistent with the established excess postexercise oxygen consumption effect (49). The minimum aerobic capacity for performing structural fireground rescue tasks should be 42 ml·kg−1·min−1 or 12 METs (range: 39-45 ml·kg−1·min−1) (15, 51, 82, 91, 122). Peak blood lactate values range from 6 to 13 mmol/L when performing fireground and rescue tasks (51, 129), suggesting a high degree of anaerobic stress.

Physiological Assessment of Structural and Wildland Fireground Tasks Classified by Primary Energy System Used; This table shows different firefighter tasks, relative intensity, and relative duration in regards to which energy systems each task falls under. I.e. a structural firefighter may perform a hose pull, which stresses the ATP-PCr energy system and may only last about 10 seconds or less.

The energy expenditure that occurs during wildland firefighting tasks varies from approximately 17 ml·kg−1·min−1 (or 2.5 kcal/min) for light tasks to >30 ml·kg−1·min−1 (or >10 kcal/min) for highly demanding job requirements (e.g., uphill hiking with a pack) (29, 110). Wildland firefighters must often sustain these tasks for prolonged periods of time on consecutive days, depending on the duration of the wildfire assignment, suggesting a need for aerobic fitness and LT levels higher than in the average population (8, 110).

NSCA's Essentials of Tactical Strength and Conditioning is the ideal preparatory guide for those seeking Tactical Strength and Conditioning Facilitator® (TSAC-F®) certification, and a reference for fitness trainers who work with tactical populations such as military, law enforcement, and fire and rescue personnel. The book is available in bookstores everywhere, as well as online at the NSCA Store.

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