Sports
Marta Izo and the Grit Behind Open Water Ultramarathons
The fifth Brazilian woman to cross the English Channel shares her training routine, mental prep, and extreme crossings.
Speaking on the Girls Who Run podcast, swimmer and coach Marta Izo looks back on her journey in marathon swimming. From tackling the English Channel to the Hudson River, she shares the physical and mental dedication behind ultra-endurance open water swimming.
In the world of endurance sports, crossing the finish line requires navigating discomfort, solitude, and uncertainty. For marathon swimmers and ocean crossing athletes, the challenge is even more demanding: hours on end in open water without visual course markers, relying exclusively on stroke rhythm and psychological stability. As the fifth Brazilian woman to complete a solo crossing of the English Channel, swimmer and coach Marta Izo joined the Girls Who Run podcast to share the lessons gathered across decades in open water.
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From a 17-Year Hiatus to the English Channel Dream
Marta’s relationship with swimming began at age 6, on a doctor's recommendation so she could join her sister during bronchitis treatments. After competing as a registered athlete until age 17 for prominent Brazilian clubs like Espéria and Pinheiros, she stepped away to pursue a degree in Physical Education. The break lasted 17 years—a period during which she played baseball for seven seasons and taught swim lessons without competitive training of her own.
The dream of swimming the English Channel, dormant since her teens, resurfaced at age 33 during a Watsu certification course. Determined to turn the ambition into a concrete goal, Marta resumed training in 2004 at age 34. Preparing for the crossing meant overcoming a common hurdle for pool swimmers: the fear of open water. Combining visualization, breathing techniques, and steady training across reservoirs and the ocean, she built the foundation needed for the challenge.
The Solo Crossing and the Four-Hour Wall
To make her 2006 solo crossing a reality, Marta took on an intense routine, with peak training weeks hitting 100 km (62 miles) and weekend volumes of 15 to 20 continuous kilometers (9 to 12 miles). Logistics at the English Channel require waiting for weather windows and following strict escort boat rules.
In the water, her fueling strategy was strictly liquid, spaced every 30 minutes for the first four hours and gradually tightened to 15-minute intervals until the finish. According to Izo, the window between 3.5 and 4 hours represents the critical threshold for pain and mental adaptation in marathon swimming—comparable to the 20-mile wall in a marathon. Once past that hurdle, the body enters a flow state. Marta completed the swim between England and France in 12 hours and 43 minutes of continuous swimming.
World Records and 193 km on the Hudson River
In 2011, Marta returned to the English Channel for a four-woman two-way relay crossing (England–France–England). The team set world records at the time for both the one-way leg, completed in 8 hours and 22 minutes, and the full two-way crossing, clocked at 18 hours and 42 minutes.
Years later, in 2017 at age 47, she tackled the 8 Bridges Hudson River Swim in New York. The event spanned 193 km (120 miles) across seven days of continuous swimming down the Hudson River, with daily stages ranging from 20 to 32 km amid strong winds and low water visibility. Her recovery protocol involved electrical muscle stimulation (TENS), whirlpool therapy, and strict nutritional support to offset extreme calorie deficits.
From Athlete to Mentor: A New Challenge on the Brazilian Coast
Today, leading the coaching agency Anjos d'Água and directing training sessions in São Paulo, Marta focuses on passing her experience along to emerging and developing swimmers. Her next project gathers the coach and seven athletes for a relay challenge between Ilha Grande (RJ) and Ilhabela (SP), totaling roughly 120 km (75 miles) in open water with swimmer rotations every 30 minutes.
For Marta, open water ultramarathons go far beyond setting records; they foster resilience and belonging within the athletic community, reinforcing the value of helping newcomers overcome their fear of open water.
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