scholarly journals Handgrip strength and 2D : 4D in women: homogeneous samples challenge the (apparent) gender paradox

2021 ◽  
Vol 288 (1964) ◽  
Author(s):  
Nora Bäck ◽  
Katrin Schaefer ◽  
Sonja Windhager

The length ratio between the second and the fourth digit (2D : 4D) is a retrospective, non-invasive biomarker for prenatal androgen exposure. It was found to be negatively correlated with handgrip strength (HGS) in men, but the evidence for women is mixed. Such studies in women call for increased detection sensitivity. The present study was designed to reduce potential confounding factors, especially age and ethnicity variation. We measured the digit ratios and HGS of 125 healthy women between 19 and 31 years of age from a remote region in Austria. 2D : 4D of both hands was significantly and negatively correlated with HGS ( n = 125, right hand: r = –0.255, p = 0.002, left hand: r = –0.206, p = 0.011). Size, direction and significance of correlation coefficients remained stable when statistically controlling for age, body weight, body height, body mass index or hours of exercise per week. This yields theory-consistent evidence that HGS and 2D : 4D are clearly associated in women—when sufficiently reducing genetic variation (confounding 2D : 4D), the ontogenetic environment and age ranges (confounding HGS) in the study population. This finding implies similar organizing effects of prenatal androgens as in men, pointing to a more parsimonious developmental mechanism and a new look into its proximate and ultimate causes.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luisa Ernsten ◽  
Lisa M. Körner ◽  
Martin Heil ◽  
Gareth Richards ◽  
Nora K. Schaal

AbstractHands and digits tend to be sexually dimorphic and may reflect prenatal androgen exposure. In the past years, the literature introduced several hand and digit measures, but there is a lack of studies in prepubertal cohorts. The available literature reports more heterogeneous findings in prepubertal compared to postpubertal cohorts. The comparability of the available studies is further limited by the study design and different measurement techniques. The present study compared the reliability and sex differences of available hand and digit measures, namely digit lengths of 2D, 3D, 4D, 5D, digit ratios 2D:4D, 2D:5D, 3D:4D, 3D:5D, 4D:5D, relative digit lengths rel2, rel3, rel4, rel5, directional asymmetry of right and left 2D:4D (Dr-l), hand width, length, and index of 399 male and 364 female 6-month-old German infants within one study using only indirect and computer-assisted measurements. The inter-examiner reliability was excellent while the test-retest reliability of hand scans was only moderate to high. Boys exhibited longer digits as well as wider and longer hands than girls, but smaller digit ratios, with ratios comprising the fifth digit revealing the largest effect sizes. Other hand and digit ratios revealed sex differences to some extent. The findings promote the assumption of sexual dimorphic hand and digit measures. However, by comparing the results of the available literature, there remains an uncertainty regarding the underlying hypothesis. Specifically in prepubertal cohorts, i.e. before the influence of fluctuating hormones, significant effects should be expected. It seems like other factors than the influence of prenatal androgens contribute to the sexual dimorphism in hand and digit lengths.


2020 ◽  
Author(s):  
Gideon Nave ◽  
Christina M. Koppin ◽  
Dylan Manfredi ◽  
Gareth Richards ◽  
Steven J. Watson ◽  
...  

AbstractThe second-to-fourth digit ratio (2D:4D) has been associated with sexual dimorphism, with a lower 2D:4D in males. A large body of research has relied on the 2D:4D as a proxy for prenatal androgen exposure, and includes reports of relationships between 2D:4D and a wide range of human traits. Here, we examine the validity of the 2D:4D proxy by studying the association between 2D:4D and classical Congenital Adrenal Hyperplasia (CAH) due to 21-hydroxylase deficiency, a condition characterized by excessive prenatal exposure to androgens during most of the gestational period. To this end, we retrospectively examine 513 serial radiographs of the left hand obtained clinically in 90 youth with classical CAH (45 female) and 70 control youth (31 female). Replicating previous reports, we observe associations of the 2D:4D with sex (lower 2D:4D in males) and age (increase of 2D:4D through development). However, we find no evidence for differences in 2D:4D between CAH and controls (full sample: □ = -0.001 (−0.008, 0.006)]; females: □ = -0.004 [-0.015, 0.007]; males: □ = 0.001, [-0.008, 0.011]). Although our findings do not rule out a small association between the 2D:4D and CAH, they cast doubt on the usefulness of the 2D:4D as a biomarker for prenatal androgen exposure in behavioral research.


2008 ◽  
Vol 103 (3) ◽  
pp. 783-792 ◽  
Author(s):  
Martin Voracek

The associations of digit ratio (2D:4D), a likely marker for prenatal androgen exposure, and absolute finger length, a likely marker for postnatal androgen exposure, with self-reports on three Pavlovian temperament dimensions (strength of excitation, strength of inhibition, and mobility of nervous processes) were investigated in a sample of 84 men and 114 women. In men, left-hand 2D:4D was weakly, but significantly, negatively associated with strength of inhibition, and also weakly negatively, but not significantly, associated with the two other temperament dimensions. These effects were absent for men's right-hand 2D:4D. Finger lengths of both hands in men were weakly, but significantly, positively associated with mobility of nervous processes scores. All associations for women were negligible. Both prenatal and postnatal androgen action may contribute to small amounts of individual differences in Pavlovian temperament dimensions in men but apparently not in women.


Endocrinology ◽  
2009 ◽  
Vol 150 (11) ◽  
pp. 5119-5124 ◽  
Author(s):  
Sheri A. Berenbaum ◽  
Kristina Korman Bryk ◽  
Nicole Nowak ◽  
Charmian A. Quigley ◽  
Scott Moffat

Interest in biological substrates of sex-related variations in psychological and physiological characteristics has led to a search for biomarkers of prenatal hormone exposure that can be measured postnatally. There has been particular interest in digit ratio, the relative lengths of the second and fourth fingers (2D:4D), but its validity as a measure of prenatal androgen has not been established. We report the strongest evaluation of the value of 2D:4D as a biomarker for early androgen exposure. Individuals with 46,XY karyotype but no effective prenatal androgen exposure due to complete androgen insensitivity syndrome had digit ratios that were feminized: they were higher than those of typical men and similar to those of typical women. Nevertheless, the effect was modest in size, and there was considerable within-group variability and between-group overlap, indicating that digit ratio is not a good marker of individual differences in prenatal androgen exposure.


2015 ◽  
Vol 6 (2) ◽  
pp. 149-157 ◽  
Author(s):  
E. S. Barrett ◽  
L. E. Parlett ◽  
S. H. Swan

The prenatal hormonal milieu is widely believed to shape health later in life; however, there are considerable methodological challenges associated with measuring the in utero hormonal environment. Two potential biomarkers of prenatal androgen exposure that can be measured postnatally have been proposed: anogenital distance (AGD) and the ratio of the second to fourth digits of the hand (2D:4D). Although both measures are widely used research tools, their use in adult women may be complicated by the dramatic fluctuations in reproductive hormones across the menstrual cycle. To determine whether there is cyclical variation in these biomarkers, we conducted a longitudinal study of 12 naturally cycling, nulliparous adult women. Trained examiners assessed two measures of AGD [anus to clitoris (AGD-AC) and anus to fourchette (AGD-AF)] and 2D:4D in both hands for the duration of three menstrual cycles, taking measurements during the follicular, peri-ovulatory and luteal phases of each cycle. Despite the small sample size, longer (more masculine) AGD was associated with lower (more masculine) digit ratios, as predicted by the literature. Using multi-level linear regression models, we found that AGD and 2D:4D measurements did not differ significantly across cycle phases. AGD-AF and digit ratios in both hands were associated with age at menarche, suggesting a possible common developmental trajectory. These results demonstrate that AGD and 2D:4D are stable across the menstrual cycle. In addition, research is needed to determine how reliably these measures reflect the in utero hormonal milieu.


2021 ◽  
Author(s):  
Zheng Li ◽  
Meng-jiao Xu ◽  
Hong Xia ◽  
Huai-fang Li ◽  
Binggen Zhu

Abstract Background The distance between clitoris and urethral meatus (CUMD) for women has been considered to likely reflect the extent of prenatal androgen exposure, being similar to the anogenital distance (AGD) and the digit length ratio. But no published work has examined the association between the CUMD and the AGD or digit ratio and the effect of body weight on CUMD and AGD.Methods The CUMD and AGD (including AGD-AC, from the anus to the anterior clitoris; AGD-AF, from the anus to the posterior fourchette) measurements for 117 women (18-45 years) were taken using a digital caliper, and the digit ratios were measured from photos by a digital camera. Meanwhile, data of their height, weight, and body mass index (BMI) were collected at same time. Results In bivariate correlation analyses of all 117 subjects, two AGD measurements (AGD-AC and AGD-AF) were moderately correlated with one another (r=0.474, p<0.001), but the correlation between AGD-AC and CUMD was weak (r=0.172, p=0.063). Both AGD-AC and AGD-AF were notably correlated with weight (r=0.290, p=0.002 and r=0.189, p=0.041; respectively) and BMI (r=0.341, p<0.001 and r=0.204, p=0.027; respectively), whereas the CUMD was not affected by weight or BMI. Exclusion of obese individuals, the CUMD of 86 non-overweight subjects was obviously correlated with the AGD-AC (r=0.236, p=0.028). Conclusion These results indicated that the CUMD could be a marker of prenatal androgen exposure without influence of body weight, superior to AGD-AC or AGD-AF.


2014 ◽  
Vol 32 (4_suppl) ◽  
pp. 231-231
Author(s):  
Michael Stolten ◽  
Elisa Ledet ◽  
Aryeneesh Dotiwala ◽  
Eric Luk ◽  
A. Oliver Sartor ◽  
...  

231 Background: During gestation, development of the prostate is dependent on a functional androgen receptor and the presence of dihydrotestosterone. Prenatal androgen exposure has been correlated with a range of diseases including prostate cancer (PCa). Historically, the ratio of the second to the fourth digit (2D:4D) has been linked to prenatal androgen levels; however, the use of alternate finger ratios have been shown to be a greater indicator of prenatal androgen exposure compared to the traditional 2D:4D ratio. Studies have shown that the distal fingertip extent of the second digit (2T:2D) was also associated with prenatal androgens. This study aims to use alternative digit ratio measurements to determine aggressiveness of PCa. Our hypothesis is that alternative digit ratios are more sensitive to prenatal androgen levels, and a better predictor of disease than the traditional 2D:4D ratio. Methods: Digital measurements were made from hand scans of PCa patients. All fingers on the right hand were measured from the basal crease to the fingertip as well as the distal fingertip extent of the second digit. Race, family history (FH) (first degree relatives with PCa), and age at diagnosis were recorded. These clinical covariates were then compared to the finger length ratios which were dichotomized based on the median values and analyzed for possible correlations. Results: Hand measurements were taken on 350 Caucasian (CA) and 100 African American (AA) PCa patients. AA men were more likely to have a smaller 2D:3D (P < 0.0001) and 2D:4D digit ratio (P < 0.0001), and larger 3D:5D (P = 0.0002) and 4D:5D (P = 0.0125) when compared to CA men. AA men with a smaller 2T:2D ratio were younger at the time of diagnosis (P = 0.0446). Additionally, AA men with a larger 2D:5D ratio were more likely to have a FH of PCa (P= 0.0238). Conclusions: Alternative finger length ratios show strong differences between AA and CA men. In AA men, alternative digit ratios are associated with age of PCa diagnosis and FH of PCa. These hypothesis generating results require validation in a larger cohort, but may provide insight to the underlying racial disparity observed in PCa. Finger length may represent a unique, non-invasive predictor of PCa, specifically age of onset and FH in AA men.


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