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Tactical Strength and Conditioning

(25) EFFECT OF ON-DUTY CIRCUIT VS. HEAVY RESISTANCE TRAINING ON NEUROMUSCULAR FUNCTION IN STRUCTURAL FIREFIGHTERS

Friday, July 12, 2024
10:30 AM – 12:00 PM East Coast USA Time
Location: Exhibit Hall
Abstract Details: Background: The National Fire Protection Association (NFPA) reports approximately 65,000 firefighter injuries annually; 21% of fireground injuries result from a slip/trip/fall and 40% are classified as a strain, sprain, or muscular pain. Firefighters are recommended to perform on-duty resistance training to enhance occupational readiness and safety, however, it’s unclear how exercise-induced fatigue may impact firefighters’ ability to safely perform subsequent occupational tasks, as fatigue is considered a risk factor for slip/trip/fall-related injuries.  Heavy resistance and circuit training modalities are commonly utilized to meet these objectives and exercise sessions are often interrupted with emergency responses requiring that occupational tasks are performed in a fatigued state, potentially increasing injury risk.

Purpose: The primary aim of this study was to compare the effects of circuit versus heavy resistance training fatigue on neuromuscular function in firefighters.

Methods: A convenience sample of 12 career structural firefighters (Age: 40.3±9.1 yr; Fat: 27.3±7.0%) were recruited from a local fire department. Participants completed 3 testing sessions, separated by at least 72 hr. During Session 1 anthropometrics and familiarization trials of the balance and neuromuscular function assessments were completed, which included single-leg drop landing (SLDL), postural sway (PS), and modified Functional Balance Test (mFBT). The mFBT required ambulation on a plank while maneuvering over and under standardized barriers.  Sessions 2 and 3 were randomized, where participants completed either heavy resistance training (HRT; 5 repetition maximum (RM) load, 2 min recovery) or a circuit training (CT; 10RM load, 45 s recovery) session. Isometric midthigh pull (IMTP), long jump (LJ) lower body power, static and dynamic balance assessments were conducted pre- and 10 min post-exercise. Repeated measures ANOVA, effect sizes, and absolute and relative difference scores were used to analyze the effect of condition and time. Level of significance was set at p< 0.05.

Results: IMTP, LJ, and LBP decreased following CT and HRT (p≤0.019, ES≥0.409). Bi- and unipedal anterior-posterior PS mean velocity decrements were greater following CT compared to HRT (p=0.045). Despite not reaching significance, several additional balance variables exhibited large effect sizes reflecting greater potential decrements in neuromuscular function following CT. 

Conclusions: These findings suggest that on-duty resistance training reduces firefighters’ strength and power immediately post-exercise and that CT may impact some measures of static balance greater than HRT. PRACTICAL APPLICATIONS: On-duty exercise is critical to enhance firefighter readiness and safety. Firefighters are recommended to exercise during low call volume times and limit exposure to high volume circuit training stimuli to reduce the effects of post-exercise fatigue on risk of subsequent occupational injury. Heavy resistance training may be a better option than circuit training during on-duty exercise. 

Acknowledgements: None