Genetics and progress: what you can actually change

Two people run the same program, eat the same and sleep the same. Six months later one has added 45 kg to their squat and the other 15 kg. That is not an excuse, it is a measured phenomenon. Here is what genetics actually controls, what it does not, and how to set up training around it.

How big the range really is

The most cited study on this followed about 585 people through 12 weeks of an identical arm training program. Average growth in muscle cross-sectional area was around 19 percent, but the range ran from 0 to nearly 60 percent. Strength went up about 54 percent on average, with individuals ranging from a few percent to over 250 percent. Same training, same supervision, a tenfold difference in outcome.

Two things follow. If you are in the top third, you will progress on a mediocre program, so do not credit the program. If you are in the bottom third, you will still progress, but you need a longer horizon and cleaner execution of the basics.

What genetics does determine

• Leverages. Femur, torso and forearm length. Long legs with a short torso means more forward lean in the squat and usually a squat that lags behind your deadlift.
• Muscle belly length and insertions. A short biceps belly with a big gap to the elbow will never look full, no matter how you train it.
• Fiber type ratio. The average is roughly 50 percent fast twitch, but people fall anywhere from about 20 to 80 percent. This is why some respond better to triples and others to sets of 10.
• Satellite cell and myonuclei count. The fastest responders walk in with more nuclei per fiber before they ever train.
• Recovery speed. One person handles 20 sets per week for legs, another falls apart at 12.

What it does not determine

It does not determine your technique, your consistency, or how much weight is on the bar five years from now. Genetics sets the slope of the curve, not its length. Someone with a poor response who trains for ten years without stopping will out-lift someone with great genetics who takes a month off every six weeks.

How to measure your own response

Do not guess. Take 10 weeks, hold one program, and track:

1. Bodyweight in the morning, fasted, three times a week, then compare weekly averages.
2. Relaxed upper arm and thigh circumference at the same marked point, every two weeks.
3. Estimated 1RM on squat, bench and deadlift, taken from a set of 5 with two reps in reserve.

If 10 weeks give you 1.5 to 2.5 kg of bodyweight along with rising circumferences and lifts, your response is above average. If strength moved less than 5 percent and nothing changed in circumference, check sleep, calories and missed sessions first, then think about genetics.

Match volume to your response

The working range for most people is 10 to 20 hard sets per muscle group per week. Start at 12 to 14 and hold it for eight weeks. If you are progressing, add 2 sets every fourth week up to the ceiling. If a joint starts complaining or your main lifts stall three sessions in a row, drop 4 sets back.

If you recover slowly, split the volume across more days. The same weekly total is far easier to absorb as three days of 5 sets than one day of 15.

Leverages and exercise selection

Do not fight your skeleton. Long arms and a narrow ribcage mean a poor bench and a great deadlift. If that is you, bench with a slightly narrower grip and add 2 to 3 sets of incline press instead of grinding the same weight every Monday for a year.

Long femurs? Try squatting in shoes with a 15 to 20 mm heel and widen your stance by roughly one hand width. That single change is often worth 5 to 10 kg immediately.

A realistic rate of progress

• First year of consistent training: 30 to 50 kg on the squat, 20 to 35 kg on the deadlift, 15 to 25 kg on the bench.
• Second year: roughly a third of that.
• After year five: 2 to 5 kg per lift per year is a normal, good result.

When to see a doctor

Genetics is a convenient explanation, which makes it easy to hide something medical behind it. See a doctor if you have no progress plus constant fatigue for more than three months, unintentional weight loss, dropping libido with heavy morning grogginess, joint pain lasting more than two weeks, or chest pressure and breathlessness out of proportion to the effort. A basic blood panel with iron, ferritin, vitamin D and thyroid values answers most of these questions.

The short version

• Response to identical training varies tenfold, from 0 to over 50 percent growth in 12 weeks.
• Genes set how fast you progress, consistency sets how far you get.
• Measure for 10 weeks: bodyweight, circumferences, estimated 1RM, then draw conclusions.
• Hold 10 to 20 sets per group per week and spread them over more days if you recover slowly.
• Pick exercises that fit your leverages instead of forcing what your build will not allow.