Transgender Biology

Body Composition & Size

Muscle mass: Males have 40-50% more upper body muscle, 20-30% more lower body muscle
Muscle fiber size: Males have larger, denser muscle fibers (Type I and II)
Body fat: Females average 6-11% higher body fat (essential for fertility)
Bone mass: Males have 30-35% more bone mass overall, 50% stronger upper body bones
Pelvic structure: Females have wider pelvis, optimized for childbirth, compromising speed and stability
Heart size: Males have a heart 20-25% larger, with higher cardiac output
Lung capacity: Males have 30% larger lung volume on average
VO2 max (oxygen uptake): Males average 15-30% higher

Strength & Performance

Grip strength: Males average 60-70% stronger
Upper body strength: Males have 50% more strength
Lower body strength: Males have 30% more strength
Sprint speed: Males are 10-15% faster in sprinting events
Endurance running: Males 10-20% advantage in endurance events
Throwing velocity and distance: Males have 30-50% advantage
Vertical jump: Males jump 20-30% higher

Blood & Circulation

Hemoglobin: Males have 12-15% higher hemoglobin, increasing oxygen carrying capacity
Red blood cell count: Males have 10-15% higher RBC count

Metabolism & Hormones

Testosterone levels: Males have 10-20 times higher baseline testosterone
Basal Metabolic Rate (BMR): Males have 5-10% higher BMR (burn more calories at rest)
Estrogen dominance: Females have 6-8x higher estrogen levels

Brain & Neurology (average tendencies)

Corpus Callosum (brain hemisphere connector): Females have more cross-hemisphere connections
Amygdala (emotional processing): Males have larger right amygdala, Females have larger left amygdala
Spatial ability (mental rotation tasks): Males outperform females by 8-10%
Verbal fluency & empathy: Females score higher on average by 10-15%

Even with hormone therapy, surgery, or blockers, most of these biological advantages are only reduced, not eliminated. Here’s why:

What changes with hormones?

Testosterone suppression: Lowers muscle mass, strength, hemoglobin, and stamina somewhat
Estrogen therapy: Redistributes fat to more female patterns, softens skin, may reduce libido
Muscle mass loss: After 1 year, trans women lose 5-15% of muscle mass, but still retain advantage over females
Strength loss: Studies show only about 5-10% strength decrease—still above female averages
Hemoglobin drops: Near female levels, reducing endurance slightly, but VO2 max and heart size remain larger

What cannot change?

Skeleton size and structure: Bone length, pelvis width, shoulder width, hand/foot size remain unchanged
Lung size & heart size: Stay the same (meaning trans women still have bigger lungs, hearts, and circulatory capacity)
Fast-twitch muscle fibers: Do not fully revert; trans women retain more power and speed
Neurological wiring: Brain structures remain fundamentally male
Height: Obviously unaffected
Bone density: Reduces somewhat with hormone therapy, but still stronger than biological females
Gametes: Cannot produce eggs or menstruate. Sperm production stops, but DNA is still XY

Studies confirm:

Even after 3+ years of hormone therapy, **trans women retain about a 12-20% advantage in strength, speed, and power over cis women
This is why even some progressive sports scientists admit there is no “leveling” after hormone therapy

Bottom line?
Hormones make cosmetic and metabolic tweaks, but biology is baked in deep—from the skeleton to the lungs to the DNA. You can dull the sword, but it is still a sword.