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Androgenic profile & male metabolism
Free T and AR density, DHT vs muscle anabolism, estradiol benefits, glycogen use, 2–3 min rest.
1. Testosterone: total, free, and receptor density
Testosterone is the primary male anabolic hormone—but high total testosterone on a lab report does not guarantee faster hypertrophy.
Testosterone fractions
- Bound: most is bound to SHBG and albumin—inert, cannot enter muscle cells.
- Free (~1–2%): the only pool that crosses membranes and drives protein synthesis.
Androgen receptor density (AR)
Hypertrophy is limited by receptor number and sensitivity. Males express more AR in the upper torso (traps, delts, chest)—those regions adapt faster to lifting.
2. Conversions: DHT and estradiol
DHT via 5-alpha reductase
5-alpha reductase converts testosterone to DHT—the strongest androgen for neural drive, aggression, and libido. Skeletal muscle deactivates DHT quickly—little direct hypertrophy; main effects are CNS/prostate.
Estradiol via aromatase
Aromatase turns some testosterone into estradiol. Physiological estrogen is required, not optional:
- Anabolic synergy: up-regulates AR density and local IGF-1.
- Joint and CNS protection under heavy training.
- Cardiovascular: helps preserve HDL.
3. Male metabolism and fatigue kinetics
- Glycogen-dominant fuel: men rely more on glycogen and burn less fat, more amino acids per bout—glycogen depletes faster.
- Lower fatigue resistance: more Type II fibers—~4–5 reps to failure at 85% 1RM is typical.
- Longer rest: slower metabolite clearance and PCr resynthesis—120–180+ seconds on compounds to keep loads up set to set.