Early Fat Loss and Plateau in Firefighter Recruits: Longitudinal Tracking of Body Composition Using Skinfold Analysis...

Area of Science:

• Exercise Physiology
• Sports Science
• Occupational Health

Background:

• Firefighter training academies involve intense physical demands.
• Monitoring body composition changes is crucial for assessing recruit adaptation and health.
• Multifrequency bioelectrical impedance analysis (MF-BIA) and skinfold analysis (SKF) are common methods for body composition assessment.

Purpose of the Study:

• To evaluate how MF-BIA and SKF track body composition changes in firefighter recruits during training.
• To compare the longitudinal tracking capabilities of MF-BIA and SKF for fat mass (FM), fat-free mass (FFM), and body fat percentage (BF%).

Main Methods:

• Thirty-nine male firefighter recruits participated in a structured exercise training program.
• Body composition was assessed using MF-BIA and SKF at five distinct time points (T1-T5) throughout the academy.
• Linear mixed-effects models were used to analyze longitudinal changes and cross-sectional differences between methods.

Main Results:

• Both MF-BIA and SKF demonstrated similar tracking of longitudinal changes in BF%, FM, and FFM, with no significant method-by-time interactions.
• Significant reductions in BF% and FM were observed from the beginning of training (T1) through later time points (T3-T5), indicating substantial early changes.
• Body composition changes plateaued between 12 and 18 weeks of training, with no significant differences between adjacent time points after the initial phase.

Conclusions:

• MF-BIA and SKF are reliable for monitoring group-level body composition changes over time in firefighter recruits.
• The primary body composition adaptations occur early in training, followed by a plateau.
• While strongly associated, MF-BIA and SKF should not be used interchangeably for individual assessments due to limited agreement.