Blair T Crewther1, Christian J Cook2. 1. Institute of Sport - National Research Institute, Warsaw, Poland; Hamlyn Centre, Imperial College, UK. Electronic address: blair.crewther@gmail.com. 2. Hamlyn Centre, Imperial College, UK; University of Canberra - Research Institute for Sport and Exercise, University of Canberra, Canberra, Australia; School of Sport, Health and Exercise Sciences, Bangor University, Bangor, UK.
Abstract
BACKGROUND: The 2nd to 4th digit ratio (2D:4D) is regarded as a sexually dimorphic trait governed by prenatal testosterone (T) and estradiol exposure. However, relationships between the 2D:4D and adult sex hormone concentrations are inconsistent in females. Environmental contingencies (e.g., physical training) may provide a stronger basis for establishing these linkages, particularly if the relationships are plastic and not fixed. AIMS: To investigate associations between 2D:4D, training hours and salivary T (sal-T) measures in physically-active women. STUDY DESIGN: Descriptive and quasi-experimental monitoring across the follicular (day 7), ovulatory (day 14) and luteal (day 21) phases of three menstrual cycles. SUBJECTS: 35 naturally-cycling women training regularly for sport (range 3-12 h a week). OUTCOME MEASURES: Morning sal-T concentrations and changes in sal-T to a physical and psychological stimulus (~10 min) were measured. RESULTS: Both 2D:4D and training hours were related to morning sal-T concentrations in all three menstrual phases (p < 0.01) and their interaction was significant during ovulation. Follow-up testing revealed a negative 2D:4D and sal-T association in women reporting high, but not low, training hours each week. Participant 2D:4D was also related to sal-T changes under physical and/or psychological challenge across each menstrual phase (p < 0.01), whereas training hours and its interaction with 2D:4D were not significant predictors of these outcomes. CONCLUSIONS: 2D:4D linkages with basal and challenge-induced sal-T changes were identified in women undertaking regular physical training. Training hours also moderated the 2D:4D link to morning sal-T, but with some menstrual-phase dependency. These complexities and environmental relationships may help reconcile conflicting results.
BACKGROUND: The 2nd to 4th digit ratio (2D:4D) is regarded as a sexually dimorphic trait governed by prenatal testosterone (T) and estradiol exposure. However, relationships between the 2D:4D and adult sex hormone concentrations are inconsistent in females. Environmental contingencies (e.g., physical training) may provide a stronger basis for establishing these linkages, particularly if the relationships are plastic and not fixed. AIMS: To investigate associations between 2D:4D, training hours and salivary T (sal-T) measures in physically-active women. STUDY DESIGN: Descriptive and quasi-experimental monitoring across the follicular (day 7), ovulatory (day 14) and luteal (day 21) phases of three menstrual cycles. SUBJECTS: 35 naturally-cycling women training regularly for sport (range 3-12 h a week). OUTCOME MEASURES: Morning sal-T concentrations and changes in sal-T to a physical and psychological stimulus (~10 min) were measured. RESULTS: Both 2D:4D and training hours were related to morning sal-T concentrations in all three menstrual phases (p < 0.01) and their interaction was significant during ovulation. Follow-up testing revealed a negative 2D:4D and sal-T association in women reporting high, but not low, training hours each week. Participant 2D:4D was also related to sal-T changes under physical and/or psychological challenge across each menstrual phase (p < 0.01), whereas training hours and its interaction with 2D:4D were not significant predictors of these outcomes. CONCLUSIONS: 2D:4D linkages with basal and challenge-induced sal-T changes were identified in women undertaking regular physical training. Training hours also moderated the 2D:4D link to morning sal-T, but with some menstrual-phase dependency. These complexities and environmental relationships may help reconcile conflicting results.
Authors: Emma Eklund; Lena Ekström; John-Olof Thörngren; Magnus Ericsson; Bo Berglund; Angelica Lindén Hirschberg Journal: Front Endocrinol (Lausanne) Date: 2020-05-12 Impact factor: 5.555
Authors: Anna Kasielska-Trojan; J T Manning; A Antczak; A Dutkowska; W Kuczyński; A Sitek; B Antoszewski Journal: Sci Rep Date: 2020-07-09 Impact factor: 4.379