The Influence of Habitual Protein Intake on Body Composition and Muscular Strength in Career Firefighters

ABSTRACT

Objective: The aim of this research was to determine the relationship among protein (PRO) intake, body composition, and muscle strength in overweight and obese firefighters. A secondary objective was to evaluate differences in body composition and muscle strength among overweight and obese firefighters with low (L; < 0.8 g·kg⁻¹), moderate (M; 0.8–1.0 g·kg⁻¹), and high (H; > 1.0 g·kg⁻¹) PRO intake.

Methods: Relative PRO intake [r_PRO] was evaluated from 3-day dietary logs, self-reported by 43 overweight and obese male career firefighters (mean ± standard deviation; age = 37.3 ± 7.2 years; body mass index = 33.2 ± 5.0 kg·m⁻²; percent body fat [%BF] = 28.9 ± 4.0%). Body composition (fat mass [FM], %BF, lean mass [LM], percent LM [%LM]) and muscle strength (peak torque [PT], relative peak torque [r_PT] of the leg extensors) were measured using dual-energy x-ray absorptiometry and isokinetic dynamometry, respectively.

Results: Greater r_PRO was associated with less FM, %BF, LM (r = −0.498 to −0.363) and greater %LM (r = 0.363), but not muscle strength (p > 0.05). Fat mass (r = −0.373) and %BF (r = −0.369) were associated with lower r_PT; %LM was associated with greater r_PT (r = 0.373). Individuals with L r_PRO had greater FM (mean difference ± standard error: L–H = 10.08 ± 3.18 kg), %BF (L–H = 3.8% ± 1.4%) and lower %LM (L–H = −3.7% ± 1.3%) than those with H r_PRO (p < 0.05) but no significant differences in muscle strength (p > 0.05).

Conclusions: Protein intake > 0.8 g·kg⁻¹ was associated with more favorable body composition in male career firefighters.

KEYWORDS:

• Dietary intake
• obesity
• first responder
• shift worker

Disclosure

EDR is the principle investigator of a service contract with the North Carolina Department of Public Safety. EDR and AESR are also principle investigators for a research contract with Naturex SA.

Acknowlegments

This project was supported in part by a Junior Faculty Award from the University of North Carolina at Chapel Hill and a grant from the National Institutes of Health (DK056350). EDR is the principle investigator of a service contract with the North Carolina Department of Public Safety. EDR and AESR are also principle investigators for a research contract with Naturex SA.

Additional information

Funding

This research was funded by the University of North Carolina at Chapel Hill (Junior Faculty Award) and the National Institutes of Health (D.K056350).