Muscle Strength Indexes and Its Association With Cardiometabolic Risk Factors in Adolescents: An Allometric Approach.

Background and aims: Muscle strength (MS) has been associated with better cardiometabolic health prognosis. However, the result for the beneficial relationship seems to be dependent on the influence of body size in determining MS levels. We investigate the association between allometric MS indexes and its association with cardiometabolic risk factors in adolescents. Methods: It was a cross-sectional study comprising 351 adolescents (male: 44.4%; age range 14-19 years) from Southern Brazil. MS was assessed by handgrip strength and three different allometric approaches were adopted: 1) MS index based on theoretical allometric exponent; 2) MS index including body mass and height; 3) MS index including fat-free mass and height. Obesity, high blood pressure, dyslipidemia, glucose imbalance and high-sensitivity C-reactive protein were investigated as individual factors or as combinations (either as combinations of components - presence of two adverse conditions, or number of components present in an individual - 0, 1, 2, 3+ cardiometabolic risk factors). Logistic and multinomial logistic regression analyses adjusted for confounding factors were used. The statistical significance adopted was 5%. Results: MS index based on theoretical allometric exponent was associated with lower likelihood (OR: 0.54; 95% CI: 0.28 - 0.89) for the presence of three or more cardiometabolic risk factors in the same individual. Conclusion: This study suggests that MS index based on the theoretical allometric exponent can be superior to allometric MS indexes that included body mass and height, or fat-free mass and height in representing the presence of high number of cardiometabolic risk factors in adolescents.