Fitness markers: useful for shaping training, useless as a verdict
This category is genuinely interesting and routinely oversold. What it can do is suggest where your physiology may start from. What it cannot do is tell you what you are capable of.
What can DNA say about how I train?
It can suggest tendencies: whether your muscle-fibre composition leans towards power or endurance, how much you may gain from a given training stimulus, and how you may recover. These are small effects on top of a much larger contribution from training, sleep, nutrition and consistency.
The best-studied marker here, ACTN3, has been examined in elite athletes for two decades. It shifts the odds slightly at the extreme end of sport. At the level almost everyone actually trains at, it is a curiosity that might inform how you structure a block of training — not a reason to change sport.
Which fitness markers are read from a DNA file?
Four: power versus endurance, response to training, soft-tissue injury predisposition and recovery profile. The first rests on a single well-studied variant; the others draw on several positions each and carry correspondingly weaker evidence, which the report states rather than hides.
| What we look at | Markers |
|---|---|
| Power vs endurance | ACTN3 — R577X |
| Response to training | — |
| Soft-tissue injury | COL5A1 |
| Recovery profile | — |
Does a power or endurance result limit what I can achieve?
No. A genotype describes a starting point, not a ceiling. Endurance athletes with power-leaning markers exist in large numbers, and training explains far more of the variation between people than any of these variants do. Treat the reading as one input into how you train, never as a verdict on what to train for.
The most defensible use of this category is scheduling rather than selection: a suggestion of slower recovery is a reason to look honestly at rest days, not a reason to give up on a sport you enjoy.
The other categories
- Medicines How inherited differences change the way people process common medicines, which genes a consumer DNA file covers, and the two that it cannot read reliably at all.
- Family planning What being a carrier means, which recessive conditions a consumer DNA file covers, and why a clear result is not an all-clear.
- Nutrition Which nutrition and wellness markers a consumer DNA file covers, how strong the evidence behind them is, and why a blood test still beats a genotype.
- Traits Which everyday traits can be read from a consumer DNA file, which of them rest on strong single-gene evidence, and which are much weaker than they look.
- Ancestry How an ancestry breakdown is computed from a consumer DNA file, what mtDNA and Y haplogroups add, and why two services reading the same file disagree.