This clinical trial aims to determine whether consuming beef-based protein before and after physically demanding simulated firefighting activities improves recovery, physical performance, and cognitive performance in healthy adult firefighters. The study will also compare beef-based protein meals with plant-based protein meals.
The main questions this study aims to answer are:
Does consuming beef-based protein reduce changes in markers of muscle damage, physiological stress, and muscle soreness following a simulated fire ground test?
Does consuming beef-based protein help maintain or improve physical and cognitive performance during recovery compared with plant-based protein?
Researchers will compare two ready-to-eat meal conditions: beef-based protein, and plant-based protein. Each participant will complete all two conditions in a randomized crossover design, with 14 to 21 days between conditions.
18 to 60 years of age
Current trained male or female firefighter with the Fort Worth Fire Department
Able to comply with all study procedures and the study timeline
Willing to consume only the study-provided ready-to-eat meals (RTEM) during designated study periods
Younger than 18 years or older than 60 years
Not a current firefighter with the Fort Worth Fire Department
Pregnant, breastfeeding, or planning to become pregnant during the study
Orthopedic or musculoskeletal limitations that prevent safe completion of the vertical jump or simulated fire ground test
Crossover
Beef-Based Protein Ready-to-Eat Meals
Other interventionBeef-Based Protein Ready-to-Eat Meals: Participants will consume study-provided ready-to-eat meals (RTEM) in which lean beef 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. Beef-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
Other interventionPlant-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.
Change 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.
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.
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.
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.
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.
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.
Food Satisfaction
Participants will report satisfaction with the study-provided ready-to-eat meals to characterize acceptability of each dietary condition.
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.
Frequency and Severity of Adverse Symptoms
Participants will report the frequency and severity of general symptoms or side effects associated with each dietary condition, including gastrointestinal distress, dizziness, and shortness of breath.
Change in Profile of Mood States
The Profile of Mood States (POMS) questionnaire will be used to assess changes in mood state and perceived fatigue associated with the simulated fire ground test and subsequent recovery.
Change in Trail Making Test Performance
The Trail Making Test (TMT) will be used to assess cognitive performance during recovery from the simulated fire ground test. Performance will be compared across dietary conditions.
Change in Psychomotor Vigilance Test Performance
The Psychomotor Vigilance Test (PVT) will be used to assess sustained attention and reaction-time performance during recovery from the simulated fire ground test. Performance will be compared across dietary conditions.
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Sam Houston State University
Lead sponsor
National Cattlemen's Beef Association, a contractor to the Beef Checkoff
Collaborator
