Canadian Swim Phenom McIntosh Shatters Records After Intense Altitude Training

The 18-year-old set new marks in the 400m freestyle and 200m butterfly at the 2025 US Open.

Apr. 13, 2026 at 6:09am

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A vibrant, abstract painting using rapid, energetic brushstrokes in neon shades of blue, green, and pink to depict the dynamic motion and power of a swimmer cutting through the water.An explosive, neon-hued painting captures the raw power and fluid grace of a swimmer pushing the limits of human performance.Austin Today

Canadian swimmer Summer McIntosh, 18, delivered a record-breaking performance at the 2025 US Open in Austin, Texas, setting the second-fastest time ever in the 400m freestyle and the fourth-fastest in the 200m butterfly. Just before the meet, McIntosh joined renowned coach Bob Bowman's elite squad in Colorado Springs for a grueling 24-day altitude training camp, which she credited for rapidly conditioning her body.

Why it matters

Altitude training is a controversial topic in the swimming world, with proponents touting its performance-enhancing benefits and skeptics warning of potential health risks. McIntosh's record-breaking feats at the US Open have reignited the debate, as her rapid improvement under Bowman's high-altitude regimen could inspire more swimmers to adopt similar training methods. However, the long-term impacts of such intense conditioning remain unclear, raising questions about the tradeoffs between short-term gains and long-term athlete wellbeing.

The details

In the days leading up to the 2025 US Open in Austin, the 18-year-old Canadian swim sensation Summer McIntosh joined Bob Bowman's elite professional squad in Colorado Springs for a 24-day altitude training camp. The grueling program, which included 10 training sessions per week, pushed McIntosh's body to adapt to the thin mountain air by producing more red blood cells - a physiological response that can boost endurance and speed. At the meet, McIntosh delivered a stunning performance, setting the second-fastest time ever in the 400m freestyle and the fourth-fastest in the 200m butterfly.

  • The 2025 U.S. Open took place from December 3-6, 2025 in Austin, Texas.
  • McIntosh joined Bob Bowman's altitude training camp in Colorado Springs just before the US Open meet.

The players

Summer McIntosh

An 18-year-old Canadian swimmer who set multiple records at the 2025 U.S. Open after completing an intense altitude training camp.

Bob Bowman

An elite swimming coach who led the altitude training camp that McIntosh participated in prior to the U.S. Open.

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What they’re saying

“Altitude training involves working out in environments with less oxygen, like mountain elevations, which forces the body to adapt by producing more red blood cells. This can boost endurance and speed, but it's not without debate—some experts worry about potential strain on the heart or overtraining.”

— Coleman Hodges, Writer

What’s next

As the debate around altitude training continues, experts will likely closely monitor McIntosh's long-term health and performance to better understand the risks and rewards of such extreme conditioning methods.

The takeaway

McIntosh's record-breaking performance at the US Open has reignited the debate around the use of altitude training in swimming, with proponents touting its benefits and critics warning of potential health risks. The long-term impacts of such intense conditioning remain unclear, raising questions about the tradeoffs between short-term gains and the wellbeing of elite athletes.