How far can teenage Kiwi running star Sam Ruthe go? What science and history tell us

When New Zealand runner Sam Ruthe crossed the line to break the under-18 indoor mile world record last week at Boston University, he became the 11th fastest indoor miler of all time.

By clocking the distance in 3 minutes and 48.88 seconds (3:48.88) he also became the youngest male to break the 3:50 mark in the mile – aged 16 years and 294 days.

Not only was this an unbelievable performance for a 16-year-old, it was also his first time on an indoor (banked) track.

When you also account for the 50-hour travel time from his hometown Tauranga to Boston, and subsequent jetlag, the run becomes even more extraordinary.

Yet it was another example of an emerging trend in middle-distance running, from 800 to 3000 metres: teenagers looking increasingly comfortable on the world stage.

Ruthe isn’t alone. Australia’s Cam Myers (aged 19) has continued to build on his performances from last season, recently running a world under-20 indoor mile record in New York, to become the second all-time fastest in that age group.

Between Ruthe and Myers, performances like this have many athletics fans wondering, how are these young athletes already so good?

The answer goes beyond early specialisation or simply “running more”. Research increasingly points toward how middle-distance running performance actually emerges, not just how much mileage is done in training.

The importance of ‘running economy’

In running, aerobic capacity – called “VO2 max”, the maximum volume of oxygen consumed for energy production – obviously matters. But in middle-distance running it is rarely what separates good athletes from the great ones, like Ruthe and Myers.

What typically matters is the athlete’s running economy (or efficiency), which describes how much energy is required to run at a steady pace well below their maximum aerobic capacity.

Research suggests athletes with good running economy use less energy (and therefore less oxygen) than runners with poor economy, while running at the same speed.

Further studies also highlight athletes who have similar VO2 max values can still differ by up to 30% in running economy. That difference alone can translate into large performance gaps at race pace.

The biomechanical edge

Several factors appear to influence an athlete’s running economy, especially in reducing the energetic cost to the runner.

One of the key factors is effective production and transmission of ground reaction forces – the force the body applies into the ground and receives back with each step – along with muscle stiffness.

Additionally, biomechanical traits such as lighter body mass, efficient limb proportions and optimal torso-to-leg ratios further enhance running economy.

For developing athletes like Ruthe, these characteristics appear to reduce the mechanical demands of repeated ground contacts.

Also, shorter contact times between the foot and ground, and greater use of “elastic” energy (the storage and recoil of energy in the Achilles tendon), allow speed to be sustained with less muscular effort.

This was potentially enhanced further on the Boston University track, which is widely regarded as one of the world’s fastest indoor (or “short”) tracks.

When combined with sound training, this may explain why some younger athletes such as Ruthe appear “senior-ready” much earlier than expected.

Shoe technology is improving

Another factor quietly shaping modern performances is footwear technology. (Ruthe is sponsored by Nike.)

Advances in carbon-plate design and midsole foam in “super spike” running shoes have reduced the metabolic cost of running by improving energy return and mimimising energy loss during ground contact.

Evidence suggests modern super spikes can improve performance and enhance step length (with no reduction in step frequency) by 1–2%. In a 1500-metre race, this equates to about a 15-metre advantage at the elite level.

Importantly, although super spikes are available to anyone, the benefits don’t appear to affect all athletes equally.

Lighter runners tend to compress modern foams more optimally, meaning a greater proportion of stored energy is returned during push-off in each step.

For younger athletes who already move efficiently, and are generally lighter than senior athletes, the shoes can amplify traits they already possess.

This doesn’t mean technology is a subsitute for talent, more that it rewards efficiency. This appears to be the case with Ruthe.

Where to next?

Whenever a young middle-distance runner breaks records, especially all the way from New Zealand, comparisons follow.

Norwegian star, 25-year-old Jakob Ingebrigtsen is the obvious reference point. He also ran world-class times across a range of distances as a teenager.

Before becoming an Olympic champion (1500-metres Tokyo 2021, 5000-metres Paris 2024), Ingebrigtsen ran his first 4-minute mile at 16 years and 250 days. Ruthe achieved this feat an entire year earlier.

Still, history reminds us that early excellence does not guarantee senior dominance. Many promising athletes disappear – not because they lacked talent, but because the system around them asked too much, too soon.

But according to Ruthe’s coach: “He trains like a 16-year-old, not like a fully professional.”

Nonetheless, while not training like a full pro, Ruthe has just been announced he will join Myers and Paris Olympics 1500-metre gold medallist Cole Hocker in the prestigious Bowerman Mile at the 2026 Prefontaine Classic in July.

New Zealand has a small but storied middle-distance history shaped by Olympic champions Peter Snell and John Walker. Ruthe’s recent performances have quickly elevated him into that lineage.

Despite his age, improved coaching knowledge, biomechanical understanding and technology are likely allowing his innate talent to express itself earlier.

The real story is that his performance invites us to rethink how middle-distance success emerges. Today’s best young athletes aren’t just fitter, they are more efficient, more economical and better supported to move well.

And in middle-distance running, athletes like Ruthe remind us that moving well often outweighs doing more.