Abstract 111: Effect of gender affirming hormonal therapy on muscle strength, body composition in individuals with gender incongruence

Background: As per international Olympic guidelines, transmen are allowed to compete in the male category without restrictions. For transwomen it was decided that the testosterone levels should be less than 10 nmol/L for a least period of 12 months. Muscle strength also plays a role along with testosterone in sports. No data is available with regards to muscle strength after gender affirming hormonal therapy in India. The aim of this prospective study was to assess the change in body composition and muscle strength after GAHT. Methods: This study was conducted over a period of one year in Endocrine OPD. Body composition was assessed by BIA (Bioelectrical impedance analysis) using Omron HBF 375 Karadascan in both cisgender (assigned gender at birth) and transgender (identified gender) settingsfor each participant both at baseline and at 6 months. Muscle strength was assessed using a handheld dynamometer (active force dynamometer) both at baseline (treatment naïve) and after 6 months of starting hormonal therapy. Results: A total of 21 trans females and 6 trans males were included. Among transwomen in both cis and trans settings there was increase in the whole-body fat, visceral fat and decrease in the skeletal muscle and muscle strength with a mean difference of (cis setting whole body fat + 2.1; visceral fat + 1.01; muscle % - 2.370, trans setting – whole body fat + 2.533; visceral fat + 1.22; muscle % - 2.5380) (p=< 0.001 for all). Among transmen in both cis and trans settings there was decrease in the whole-body fat, visceral fat and increase in the skeletal muscle and muscle strength with a mean difference of (cis setting – whole body fat – 0.76; visceral fat – 1.34; muscle % + 2.2 and in trans setting – whole body trans-fat – 1.06; visceral fat – 1.67; muscle % + 2.7) (p < 0.005 for all). Conclusion: Transwomen on treatment for at least 6 months showed increase in whole body fat, visceral fat, decrease in total muscle and muscle strength when compared to baseline. As there is significant reduction in muscle strength among transwomen, taking testosterone value alone into consideration for allowing them into sports is not fair. Among transmen there was increase in muscle mass and muscle strength, but it was less when compared to cis-men. It is justified to consider to take muscle strength into criteria along with testosterone levels for tanswomen.