(32) RELATIONSHIPS BETWEEN METABOLISM AND BODY COMPOSITION IN COLLEGIATE WRESTLERS DURING A SEASON

Background: Resting metabolic rate (RMR) accounts for 60-70% of total daily energy expenditure, and therefore, plays a pivotal role in energy balance and weight management. Wrestlers undergo frequent weight cycling throughout a season to compete in specific weight class categories. The high training demands and intentional energy restriction may elicit unfavorable body composition and metabolic changes throughout the season.

Purpose: The purpose of the current study was to examine relationships between resting metabolic rate (RMR) and body fat percentage (BF%) in wrestlers and potential changes throughout a season.

Methods: National Collegiate Athletic Association Division III male wrestlers (n=24; Age: 19.5 ± 1.4yr.; Body Mass: 78.4 ± 14.3 kg; Height: 176.6 ± 6.1 cm, Body Mass Index: 25.3 ± 3.8 kg/m²) participated in this longitudinal study. A three-site skinfold assessment technique was utilized to calculate body density and later convert to BF% using the Brozek equation. RMR was assessed using indirect calorimetry in a climate-controlled laboratory setting, which was also used to calculate respiratory exchange ratio (RER). RMR was also estimated using the Mifflin-St. Jeor equation and used to calculate RMRratio by dividing measured RMR by predicted RMR to evaluate indications of metabolic adaptation (RMRratio < 1.00). Repeated measures analysis of variance was used to examine changes in body composition and metabolism across the first part of the competitive season (Pre-fall camp, Post-fall camp, and Mid-season). Statistical significance was determined as p < 0.05.

Results: A significant time effect (p< 0.001) was observed for FFM, RER, and body weight. Pairwise comparisons indicated a significant increase in body weight FFM (mean difference, 95% confidence intervals) from Post-fall camp to Mid-season (2.06, 0.95-3.2 kg; p< 0.001). There was a significant reduction from Pre-fall camp to Post-fall camp (-0.92, 0.047-1.79 kg; p = 0.036), followed by a significant increase Post-fall camp to Mid-season (1.59, 0.81-2.4; p< 0.001) returning to values similar to Pre-camp as displayed in Table 1. RMRratio was above 1.2 across all time points.

Conclusions: Changes in body weight were likely mediated by alterations in FFM. Minimal changes in RMR occurred throughout the first half of a competitive wrestling season and findings suggest no signs of metabolic adaptations as indicated by RMRratio values above 1.00 throughout the season. PRACTICAL APPLICATIONS: Reductions in RER and FFM may have been a result of energy deficiency via energy restriction leading through fall camp due to the preparation of minimal weight certifications for the upcoming season. Wrestlers should increase protein intake and continue engaging in strength-training activities to minimize reductions in FFM during fall camp and throughout the season.

Acknowledgements: This study was funded by the Mayo Clinic and University of Wisconsin-La Crosse Collaborative Seed Grant.