Mg. Aguilera-Eguía, Raúl

Introduction: Bodybuildingis a sport that evaluates athletes based on their muscle mass, sym-metry, and muscle definition, unlike conventional sports that are usually based on athletic per-formance in competition. Objective: The objective of the study was to determine the relationship between fat mass (FM) and skeletal muscle mass (SMM)through bioimpedancewith sleep quality in Chilean natural bodybuilders on pre-competition day. Methodology: Twenty-sixnatural bodybuilders participated in the WNBF Chilean champion-ship. The objective was to evaluate body composition toobtain data regarding SMM and FM. Additionally, thePSQI was applied. Results: significant relationships were obtained with SMM andPSQI (p= 0, 02, R = -0,38, R²= 0.14) and a moderate correlation between FM and PSQI (p= 0.04, R = 0.40, R²= 0.15). Sleep efficiency showed a negative correlation (p= 0.001, R = -0.55, R²= 0.31) with FM and a positive correlation (p = 0.002, R = 0.58, R²= 0.34) with SMM. Sleep duration showed a negative corre-lation (p = 0.024, R = -0.39, R²= 0.15) with FM and a positive correlation (p = 0.021, R = 0.45, R²= 0.20) with SMM. Discussion: A lack of sufficient sleep has been linked to adverse effects on body composition, including reduced fat loss and muscle gain. Additionally, insufficient sleep has been associated with a decline in athletic performance.Conclusions: The findings of this study indicate that poor sleep quality is associated with higher body fat and better sleep quality with a higher skeletal muscle mass, underscoring the signifi-cance of sleep for achieving optimal body composition and performance in natural bodybuild-ers.

Introduction: heart rate variability is a key indicator of cardiovascular health and autonomic balance, influenced by various factors such as age and stress. Objective: to relate heart rate variability to body composition, physical activity levels, sleep quality, and self-perceived stress in young Chilean adults with low cardiometabolic risk. Methodology: a cross-sectional study was conducted in 2024 with the participation of 32 young adults (18 to 30 years old), selected based on inclusion criteria related to adequate physical activity levels and the absence of chronic diseases. The analysis considered variables such as body composition, sleep quality, stress levels, physical activity levels, and heart rate variability, with the latter measured over a 5-minute resting period. Results: age showed a significant negative relationship with RMSSD (β = -0.43, t = -2.48, p = .02), indicating a decrease in parasympathetic activity as age increases. Self-perceived stress, however, did not show a significant impact on RMSSD (β = .09, p = .60) or the RR/RMSSD ratio (β = -0.37, p = .04). Discussion: the findings highlight the importance of heart rate variability as an indicator of autonomic health, emphasizing how age and stress impact vagal modulation. These results reinforce the need to integrate autonomic monitoring into preventive strategies to improve cardiovascular health. Conclusion: heart rate variability is significantly related to age and self-perceived stress. These findings underline the importance of integrating autonomic monitoring into preventive health strategies.