The goal of this clinical trial is to learn whether consuming pork-based protein before and after physically demanding simulated firefighting activities can improve recovery, physical performance, and cognitive performance in healthy adult firefighters. The study will also compare pork-based protein meals with plant-based protein meals and a carbohydrate-focused control condition. The main questions this study aims to answer are: Does consuming pork-based protein reduce changes in markers of muscle damage, physiological stress, and muscle soreness following a simulated fire ground test? Does consuming pork-based protein help maintain or improve physical and cognitive performance during recovery compared with plant-based protein and a carbohydrate-focused control condition? Researchers will compare three ready-to-eat meal conditions: pork-based protein, plant-based protein, and a carbohydrate-focused control condition. Each participant will complete all three conditions in a randomized crossover design, with 14 to 21 days between conditions.
Firefighting is a physically and cognitively demanding occupation characterized by repeated exposure to strenuous activity, heat stress, heavy personal protective equipment, and time-sensitive occupational tasks. These demands can produce substantial physiological stress and fatigue that may influence recovery and readiness for subsequent occupational activities. Despite the importance of maintaining readiness between demanding events, relatively little is known about how short-term dietary strategies, particularly protein source and intake, influence recovery in career firefighters. This study will examine the effects of short-term consumption of ready-to-eat meals (RTEM) differing in protein source and quantity on physiological recovery and occupational performance following strenuous simulated firefighting activity. The study uses a randomized, double-blinded, repeated-measures crossover design in healthy adult career firefighters. Participants will complete three experimental conditions separated by a 14- to 21-day washout period. The dietary conditions consist of pork-based protein RTEM, plant-based protein RTEM, and a carbohydrate-focused lower-protein control condition. The pork- and plant-based conditions are designed to provide comparable energy and macronutrient intake while allowing investigation of potential differences associated with protein source. During each experimental condition, participants will complete a simulated fire ground test (FGT) consisting of nine occupationally relevant firefighting tasks while wearing personal protective equipment and a self-contained breathing apparatus. The FGT includes hose deployment and pulling, charged hose deployment, equipment carrying, a low-room search, forcible entry, ladder carrying, stair climbing and hose hoisting, ceiling breach activities, and a victim-dummy drag. Measures of FGT completion time, heart rate, air consumption, and work efficiency will be collected to characterize occupational performance and physiological demand. Recovery will be evaluated before the simulated firefighting activity and during the subsequent recovery period. Assessments will characterize blood-based markers of catabolism, immune stress, muscle damage, and clinical safety, as well as muscle soreness, mood, cognitive function, vertical jump performance, and subsequent occupational performance. The primary hypothesis is that the pork-based RTEM condition will attenuate catabolic responses, immune stress, muscle damage, soreness, and perceptions of fatigue following the FGT while supporting the maintenance or recovery of cognitive and physical performance. The inclusion of plant-based protein and carbohydrate-focused control conditions will help determine whether recovery responses differ according to dietary protein source and protein quantity. The findings are intended to provide preliminary evidence regarding practical, food-based nutritional strategies that may support recovery and occupational readiness among firefighters following strenuous firefighting activity.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
20
Pork-Based Protein Ready-to-Eat Meals: Participants will consume study-provided ready-to-eat meals (RTEM) in which lean pork serves as the primary protein source. Meals are designed to provide approximately 700 - 800 kcal, 80 g carbohydrate, 50 g protein, and 30 g fat per meal, with total daily protein intake targeted at approximately 1.4-2.0 g/kg/day. Pork-based meals will be provided during the approximately 3-day experimental period surrounding the simulated fire ground test and subsequent recovery assessments. Meals are designed to match the energy and macronutrient content of the plant-based protein condition.
Plant-Based Protein Ready-to-Eat Meals: Participants will consume study-provided ready-to-eat meals (RTEM) in which plant-based foods serve as the primary protein source. Plant protein sources may include soy, tempeh, tofu, and other soy-based foods. Meals are designed to provide approximately 700 - 800 kcal, 80 g carbohydrate, 50 g protein, and 30 g fat per meal, with total daily protein intake targeted at approximately 1.4-2.0 g/kg/day. Plant-based meals will be provided during the approximately 3-day experimental period surrounding the simulated fire ground test and subsequent recovery assessments and will be matched as closely as feasible to the pork-based condition for energy and macronutrient content.
Carbohydrate-Focused Lower-Protein Ready-to-Eat Meals: Participants will consume study-provided carbohydrate-focused ready-to-eat meals (RTEM) designed to provide a lower total daily protein intake of approximately 0.8 g/kg/day. This condition serves as the lower-protein dietary control for comparison with the pork-based and plant-based higher-protein conditions. Meals will be provided during the approximately 3-day experimental period surrounding the simulated fire ground test and subsequent recovery assessments.
Bob Bolen Public Safety Complex Administration
Fort Worth, Texas, United States
RECRUITINGSam Houston State University
Huntsville, Texas, United States
RECRUITINGChange in Testosterone and Cortisol
Serum testosterone and cortisol concentrations will be measured to characterize anabolic and catabolic hormonal responses following the simulated fire ground test. Changes in testosterone, cortisol, and the testosterone-to-cortisol ratio will be compared across dietary conditions.
Time frame: Baseline, 24, 48, and 72 hours following the simulated fire ground test
Change in Serum Creatine Kinase
Serum creatine kinase (CK) concentration will be measured as a marker of muscle damage and recovery following the simulated fire ground test. Changes in CK will be compared across the pork-based protein, plant-based protein, and carbohydrate-focused lower-protein dietary conditions.
Time frame: Baseline, 24, 48, and 72 hours following the simulated fire ground test
Change in Perceived Muscle Soreness
Participants will report perceived muscle soreness to characterize subjective recovery following the simulated fire ground test. Muscle soreness responses will be compared across dietary conditions.
Time frame: Pre-fire ground test and 24, 48, and 72 hours of recovery
Fire Ground Test Completion Time
Total time required to complete the simulated fire ground test (FGT) will be recorded as a measure of occupational firefighting performance. The FGT consists of standardized firefighting-related tasks performed while wearing personal protective equipment and a self-contained breathing apparatus.
Time frame: During each simulated fire ground test on Day 1 (baseline) and Day 4 (72 hour mark)
Change in Complete Blood Count With Differential
A complete blood count (CBC) with differential will be assessed to characterize hematological responses and monitor clinical safety across the experimental conditions. Measures will include standard hematological indices and leukocyte differential components reported by the clinical laboratory.
Time frame: Baseline, 24, 48, and 72 hours following the simulated fire ground test
Change in Comprehensive Metabolic Panel
A comprehensive metabolic panel (CMP) will be assessed to characterize metabolic responses and monitor clinical safety across the experimental conditions. Standard CMP components, including markers related to renal and hepatic function, electrolytes, glucose, and protein status, will be evaluated as reported by the clinical laboratory.
Time frame: Baseline, 24, 48, and 72 hours following the simulated fire ground test
Food Satisfaction
Participants will report satisfaction with the study-provided ready-to-eat meals to characterize acceptability of each dietary condition.
Time frame: At Baseline, 24, 48, and 72 hours
Heart Rate During the Fire Ground Test
Heart rate will be monitored during the simulated fire ground test to characterize cardiovascular demand during occupational firefighting activity.
Time frame: During each simulated fire ground test on Day 1 (baseline) and Day 4 (72 hour mark)
Change in Vertical Jump Performance
Vertical jump performance will be assessed as an indicator of lower-body neuromuscular performance and recovery following the simulated fire ground test. Performance will be compared across dietary conditions.
Time frame: Pre-fire ground test on Day 1 and Day 4
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