Running Better: What Genetics Explains — and What Training Transforms

Running ability depends on three main factors, each partly genetic but all amenable to training.

Is running performance determined by genetics or by training? VO₂ max, lactate threshold and running economy are three key pillars of endurance, all influenced by biology — yet profoundly shaped by training. Drawing on a recent analysis published by The Economist, this article explores what science really says about the genetics of running performance, and why running slow remains one of the most powerful tools for getting faster.

Every January, countless runners lace up their shoes with renewed motivation. Some aim to complete their first marathon, others to beat a personal best, and many simply want to run without injury. But as training progresses and performances diverge, a familiar question arises: are we all equally built for running?

According to The Economist, the answer is nuanced — and reassuring:

Running ability depends on three main factors, each partly genetic but all amenable to training.

In other words, genetics matters — but it does not decide everything.

The three pillars of running performance

1. VO₂ max: a genetically influenced ceiling — rarely reached

VO₂ max refers to the maximum amount of oxygen the body can take in, transport and use during exercise. It is influenced by heart size, capillary density in muscles, and the efficiency of mitochondria in producing energy.

Genetically, some individuals start with a higher baseline VO₂ max, or show a faster response to aerobic training. This partly explains why two people following the same training plan may improve at different rates.

However, this theoretical ceiling is rarely reached. For most recreational runners, VO₂ max can increase substantially with structured training — especially at beginner and intermediate levels.

Genetics shapes the starting point, not the true potential.

2. Lactate threshold: where genetics meets training

The lactate threshold is the exercise intensity at which lactate accumulates faster than it can be cleared from the bloodstream. Below this threshold, the body can meet its energy demands efficiently through aerobic metabolism.

Certain genetic variations influence lactate production, clearance, and muscular tolerance to acidity. This can affect how hard an effort feels at a given pace, and how quickly fatigue sets in.

Yet lactate threshold is one of the most trainable physiological parameters. Low-intensity, high-volume training drives mitochondrial and enzymatic adaptations that gradually push this threshold higher.

Genetics may influence perceived effort, but training moves the limit.

3. Running economy: efficiency shaped by structure and repetition

The third and often least discussed pillar of performance is running economy — the amount of energy required to cover a given distance at a given speed.

Running economy is influenced in part by genetically linked traits such as body morphology, limb length, tendon stiffness, neuromuscular coordination and muscle fibre composition. These factors can make a runner’s stride more or less economical.

But running economy evolves slowly and primarily through repetition. High training volume, consistency and easy-paced running allow the nervous and muscular systems to refine movement patterns, gradually reducing energy cost.

Genetics influences mechanics; training shapes efficiency.

What 120,000 runners can teach us

In the absence of high-quality randomised controlled trials comparing marathon training plans, researchers increasingly turn to real-world data. A study published in 2024 by teams based in Britain, Ireland and New Zealand analysed 16 weeks of training data from nearly 120,000 marathon runners using the fitness-tracking app Strava.

The findings were striking:

• The fastest marathon runners logged roughly three times more weekly mileage than the slowest
• The number of long runs (over 20 km) was strongly associated with faster finishing times
• Completing ten long runs over 16 weeks was linked to nearly a 50-minute improvement compared with completing none

Run slow to race fast

Crucially, most of the additional distance covered by faster runners was completed at low intensity, below the lactate threshold and slower than marathon pace.

This approach improves endurance-related physiology while reducing injury risk and recovery demands. Elite athletes typically spend around 80% of their training time running slowly.

According to Cailbhe Doherty of University College Dublin, many recreational runners are “working too hard” during training — pushing intensity instead of building volume.

Even close to race day, performance can improve

Adjustments made in the final weeks still matter:

• Tapering mileage three weeks before a race, rather than one, can improve finishing times by up to 2.6%
• Carbohydrate loading in the final 48 hours — 8 to 10 grams per kilogram of body weight — helps replenish glycogen stores, a surprisingly difficult target for many runners

Genetics, performance — and freedom

At Adnà, these findings reinforce a key principle: genetics is not destiny. DNA provides information about biological tendencies, not fixed outcomes.

Understanding individual predispositions can help personalise training, recovery and nutrition — but it never replaces consistency, patience or enjoyment of movement.

In summary

➡️ Run often
➡️ Run long
➡️ Run slow
➡️ And run with a better understanding of your body

Because sometimes, the fastest way forward is to slow down first.

Sources
– The Economist, Science & Technology, 2024
– Multi-university analysis of Strava training data, 2024