Canadian Swim Phenom McIntosh Shatters Records After Intense Altitude Training

Summer McIntosh's US Open performance raises questions about the risks and rewards of extreme high-altitude conditioning.

Apr. 13, 2026 at 1:09am

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A dynamic, expressionist painting in vibrant neon colors depicts the explosive energy and fluid motion of a swimmer cutting through the water, conveying the intense physicality of elite-level competition.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. While altitude training can boost endurance and speed by forcing the body to produce more red blood cells, some experts warn of potential risks like heart strain and overtraining. McIntosh's success suggests the approach worked for her, but critics argue the extreme methods may not be sustainable for all swimmers.

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 success at the U.S. Open has reignited the ongoing debate around altitude training in swimming. While the approach appears to have paid dividends in the short term, the potential long-term impacts on athlete health and sustainability remain unclear, raising questions about whether such intense conditioning is worth the risks for the average swimmer.