Swimming the English Channel Multiple Times: Sarah Thomas

What Sarah Thomas did

Thomas began her four way Channel attempt at approximately 1:00 AM on 15 September 2019. She finished at approximately 7:00 AM on 17 September 2019. The total elapsed time was 54 hours 10 minutes. Across the swim she covered approximately 134 statute miles or 216 km, the equivalent of nearly four times the standard 21 mile straight line crossing.

The swimmer

Sarah Thomas was born in 1982 in Conifer, Colorado. She had established a long history of marathon swimming including the Lake Memphremagog 80 mile swim in 2017 and other ultra distance open water events. She was treated for invasive ductal carcinoma in 2017 and 2018 including surgery and radiation therapy. The Channel attempt came approximately one year after completion of cancer treatment.

The crossing

Thomas swam from England to France for the first leg, France to England for the second, England to France for the third and France to England for the fourth. The swim followed the English Channel Swimming Association rules which require continuous swimming with no human contact and limited feeding from a support boat. Total distance was approximately 134 miles due to tidal currents extending the actual swimming distance.

The conditions

Water temperature during the September 2019 swim was approximately 16 to 17 degrees C. Thomas wore a standard swimming costume without a wetsuit, per Channel Swimming Association rules. The standard Channel swim rules require no thermal protection beyond swimsuit, cap and goggles. Cold tolerance must come from training, body composition and time at temperature.

The previous record

Three way English Channel swims had been completed previously. The first was by Jon Erikson in 1981. Multiple swimmers have since completed three way crossings. Thomas was the first person verified to have completed four consecutive crossings. The achievement extended the previous record by 25 percent and required swimming in a state that no prior swimmer had documented.

What 54 hours of swimming demands

Continuous ultra distance swimming combines specific physiological demands that no other endurance discipline matches. The combination of cold exposure, sustained shoulder work, fuelling difficulties and sleep deprivation creates a unique physiological challenge.

Caloric demand

Channel swimming expends approximately 600 to 800 kcal per hour. Across 54 hours the total expenditure exceeds 35000 kcal. Thomas reportedly consumed approximately 400 kcal per hour in feeding stops from the support boat. The negative energy balance produced significant cumulative deficit. Cold water exposure increases the caloric demand further through thermoregulatory needs.

Cold exposure

Sea water at 16 to 17 degrees C is cold enough to produce continuous heat loss in unprotected swimmers. Body fat distribution and overall body composition affect cold tolerance. Many successful Channel swimmers have higher body fat percentages than other elite athletes specifically to support cold tolerance. The fat insulates against heat loss and provides metabolic fuel reserves.

Shoulder load

Swimming uses repetitive shoulder motion. Across 54 hours of continuous swimming the shoulders perform approximately 200000 strokes per arm. Cumulative tendon and muscle stress is unavoidable. Channel swimmers train extensively to develop the specific tendon strength needed for ultra distance swimming. Acute and overuse injuries during long swims are common.

Sleep deprivation

Thomas swam continuously for 54 hours without sleep. Sleep deprivation produces cognitive effects within 24 to 36 hours. Decision making, motor coordination and emotional regulation all decline. The combination of physical fatigue and sleep deprivation across multiple days creates a state that few endurance disciplines require. Swimming continuously through extended sleep deprivation while monitoring conditions is distinctive to ultra distance swimming.

What returning to ultra swimming required

The Thomas achievement was made more notable by the timing in relation to her cancer treatment. Returning to elite endurance performance after cancer involves specific medical and physiological challenges.

The diagnosis and treatment

Thomas was diagnosed with invasive ductal carcinoma in 2017. Treatment included surgery and radiation therapy. She has spoken publicly about the treatment experience. Cancer treatment affects multiple body systems including cardiovascular function, muscle mass and energy levels. Return to elite endurance after cancer treatment requires careful progression.

Treatment side effects

Radiation therapy can produce cardiovascular effects, fatigue, skin changes and other longer term consequences. Modern cancer treatment is significantly more targeted than historical approaches but still produces measurable physiological effects. Elite athletes returning from cancer treatment must work around residual effects while rebuilding training capacity.

The return to training

Thomas rebuilt her swimming volume across the year following treatment. She completed multiple distance swims as preparation for the four way Channel attempt. The progressive return from cancer treatment to ultra distance swimming required sustained training without complications that might force interruption. Her medical team monitored her recovery throughout.

The Channel attempt timing

The four way attempt came approximately one year after treatment completion. The timing was conservative compared to some athletes who return to elite competition faster. The choice to attempt one of the most demanding open water swims ever attempted at this stage of recovery reflected both personal motivation and medical support for the attempt. The successful completion suggested her recovery had been thorough.

Lessons from the four way swim

The Thomas achievement extended what was thought possible in ultra distance open water swimming and demonstrated specific aspects of cancer recovery in elite athletes. The lessons inform thinking about progression, recovery and the limits of ultra endurance.

Records move as preparation methods evolve

The progression from one way Channel swims to two way, three way and now four way crossings reflects improved training methods, support and preparation. Each generation of swimmers builds on the methods of the previous. The current record will likely be exceeded over time. Performance ceilings in endurance sport are rarely absolute.

Cancer recovery can be substantial

Return to elite endurance after cancer treatment is possible with appropriate medical support and progressive training. The Thomas case is one of multiple examples of athletes returning to high level performance after cancer. The pattern is consistent with research showing that exercise during and after cancer treatment improves outcomes. Most cancer patients should be encouraged to remain or become active under medical guidance.

Cold tolerance requires preparation

Successful Channel swimming requires specific cold water training. The cold tolerance is partly trainable and partly related to body composition. Swimmers who attempt cold water work without specific preparation are at significant risk of hypothermia. Cold acclimatisation through repeated cold water exposure is essential before attempting any cold open water distance swimming.

Crossing the Channel is not training

The Thomas swim represents the absolute extreme of Channel swimming. Single Channel crossings are themselves significant achievements that require months to years of preparation. Recreational swimmers should not attempt Channel swimming without extensive cold water training, distance preparation and medical support. The achievement is at the upper limit of human capability rather than at the upper limit of recreational possibility.

More from the limits library

For another extreme open water swim, our How Ross Edgley Swam Around Great Britain guide covers Ross Edgley. Rowing the Atlantic Solo covers ocean rowing. And Extreme Cold Exposure covers Wim Hof and cold adaptation.