Workouts don't read the same to everyone
~50% of your workout response is genetic — strength gain, recovery, endurance. ACTN3 alone decides sprinter or stayer. Train smarter, not just harder.
Two friends start the same beginner programme on the same week. Six weeks in, one has added three kilos of lean mass and thirty kilos to their squat. The other is stuck and demoralised. Genetics covers about half of that gap.
The three names worth knowing
ACTN3 codes for a protein in fast-twitch fibre. ACE tilts the body toward endurance or power. PPARGC1A controls how readily your cells build mitochondria. None of them is destiny; each one tilts a probability.
Read your first month as data
If strength climbs faster than size, lean into progressive overload. If size climbs faster, volume is your friend. If neither moves, change frequency first, then volume, then load.
What the genes do not cover
Sleep, protein, and consistency are roughly the other half. Train the body you have, not the one in the textbook.