The relationship between second-to-fourth digit ratio (2D:4D), muscle strength and body composition to bone mineral density in young women

Abstract

2D:4D ratio is determined by balance between androgens and estrogens. Low level estrogen reduces bone mineral density (BMD) and incurs negative changes to bone microarchitecture, increasing the risk of osteoporosis and, as a consequence, fracture risk in women. The purpose of this study was to investigate the relationship between 2D:4D, muscle strength and body composition to BMD in young women. One hundred twenty-seven young women (age range 24-36 years) voluntarily participated in this study. Lengths of the second (index) and fourth (ring) fingers, upper and lower body strength and body composition (body mass index, BMI; waist to hip ratio, WHR) and body fat percentage were estimated. Also, blood levels of calcium and 25-hydroxyvitamin D (25OHD) were evaluated and dual-energy X-ray absorptiometry device was used to measure BMD in the lumbar spine (LS) and femoral neck (FN). The results showed that digit ratios, upper body and lower body muscle strength, BMI and fat percentage had a positive relationship with LS and FN BMD (LS BMD: r=.47, r=.56, r=.46, r=.34, r=.28, p≤.001, respectively; FN BMD: r=.34, r=.49, r=.51, r=.45, r=.27, p≤.001, respectively). In addition, there was no significant relationship between WHR and BMD of LS and FN (p˃.05). Multiple linear regression analysis showed the upper body strength was a stronger determinant of LS BMD and the lower body strength was a stronger determinant of FN BMD. Based on the results, the researchers concluded that upper and lower body strength, 2D:4D ratios and BMI were important determinants of young women’s BMD. Also, it seemed that some of these factors may be able to help predicting the osteoporosis potential in young women

Effect of sequence order of combined strength and endurance training on new adiposity indices in overweight elderly women

“…Tan et al reported that performing six months of combined training (aerobic and resistance) improved body composition and significantly reduced BMI and waist-to-hip ratio in elderly persons [30]. In addition, the results of the current research are in line with the results obtained by researchers who observed improvement of body composition indices after performing combined training in sedentary people [31].…”

Variation of Digit Ratio (2d:4d) in Athletes and Differences With Sports Groups

“…Muscular performance plays a decisive role when reaching the objective in sports competition (Aikawa et al, 2020). Muscle strength, a basic physical ability regularly developed in athletes regardless of level and sporting experience, is related to 2D:4D in both women and men (Arazi & Eghbali, 2019). It has been observed a negative relationship between muscle power output (e.g., jump tests or reaction times) and 2D:4D (Hsu et al, 2018;Tambe et al, 2017).…”