"While the exact pathophysiology of SIPE remains uncertain, it is believed to be related to exertion, immersion in cold water, and overhydration. The body's normal response to exercise is to increase cardiac output to meet the increased oxygen demand. Although an increased cardiac output is known to cause pulmonary edema in racehorses, this increase is rarely enough to produce such an effect in humans. Cold-water immersion is instrumental in this process because the peripheral vasculature constricts to divert blood away from the extremities in an effort to maintain the core body temperature. This results in a central pooling of blood, leading to an increased preload, increased pulmonary artery pressure, and an increased cardiac output. The vasoconstriction also causes an increase in afterload, which leads to an increase in pulmonary vasculature resistance. The increased cardiac output from exertional activities coupled with an increased preload and afterload from immersion appear to be sufficient to rupture the pulmonary capillary membranes, thus resulting in pulmonary edema. In several documented cases of SIPE, it has been noted that the patients consumed anywhere from two to four liters of water in the hours leading up to their swim in an effort to remain well hydrated. It is believed that this degree of hydration led to a fluid overload that contributed to the onset of pulmonary edema by increasing the pulmonary capillary pressure. Patients may present with symptoms, such as cough, dyspnea, hemoptysis, tachypnea, and confusion with hypoxia, after exertional cold water activity such as swimming and scuba diving."
First off, triathletes need to take the swim portion seriously. This includes race day tactics and swim training preparation. Far too many triathletes don't train appropriately (or enough) to be prepared for the open water. For most developing triathlon swimmers, you need to learn how to swim at different intensities in the (with proper open water techniques), have more practice in the open water, know your abilities when you start the swim portion of the race and understand the demands of your swim course (ex. waves, currents, etc.).
We need every triathlon to offer a practice swim on the morning of the race. Not only does this provide a sport-specific warm-up but it gives athlete time to acclimate to the water and to adjust swim gear to the right fit/comfort. But to be honest, even when a practice swim is allowed, most triathletes don't take advantage of this practice swim because they don't want to be wet or they want to save their energy for the actual race. At IM 70.3 FL, there is a pool at the race venue. This year, I would guess there were no more than 50 total triathletes in that pool in the 90 minutes that the pool was open before the start of the race. You want to prepare your heart for the effort of the swim before you actually start swimming.
I am strongly against the use of "boosters" before a race - caffeine, energy drinks, etc. There is so much anxiety and stress from swimming alone and the added stress on the heart is not worth it. Triathletes need to create a go-to warm-up strategy before the race - something that is familiar and well-practiced. This can help ease nerves and reduce anxiety.
There's so much emphasis on sodium before a race that many athletes are overdoing it on pre-load and salt pills in an attempt to off-set the effects of dehydration. However, a hyper-hydration style beverage (or pills) may predispose an athlete to SIPE due to the potential of retaining excessive fluid. This will be worse if an athlete already has high blood pressure. SIPE is connected to a quick increase in blood pressure.
Although a wetsuit can be to blame, many triathletes feel more comfortable swimming in a wetsuit due to the buoyancy. However, triathletes need to practice in the wetsuit (at race intensities) to ensure it's the right fit (and race intensities are realistic). Gerry Rodrigues did a great discussion on his Tower 26 podcast on finding the right wetsuit.
Things to consider:
- Many athletes go into races overly hydrated - an increase in body fluid is not a good thing.
- Abrupt cold water exposure and/or compression of the wetsuit can push fluids to the core. I advise athletes to use a bottle of water to pour down the wetsuit and try to get wet before the race so the water is not a shock to the body when you can't warm-up in the water.
- Athletes who already have high BP can experience a further increase in BP at the race start - causing fluid in the lungs (similar to flash pulmonary edema).
- Interestingly, even though research has shown cardiac issues among elite athletes, I will generalize and say that swimming related deaths appear more common in the less experienced and in males. Instead of making assumptions of the risk of death in the triathlon swim, it would be beneficial if we could better understand more about the background of the athlete who passed away. For example, did this person have a preexisting heart condition, was she/he wearing a wetsuit for the first time, is she/he on any medications/drugs, what was the nutrition like on race day morning, was she/he stressed before the race, what type of training did she/he do on race week, etc.? This additional information may help us further prevent or reduce the risk of future triathlon swimming deaths.
What can we do to reduce the risk:
- Start slow in the water - give yourself time to warm-up and get breathing under control before taking your first stroke.
- No more than 30 ounce water on race morning.
- Get a medical exam (as comprehensive as possible) before a race (or before training for a race).
- Fuel and hydrate appropriately - don't restrict, don't overdo it either.
- Take training and racing very seriously. Long distance triathlon should not be seen as the new "marathon" but as an extreme endurance event that comes with great risk.
- Choose races appropriately - consider the water temperature, water environment (ex. chop, current, etc.) and how you will prepare for your open water swim (can you do practice swims in similar conditions)?
- Test out your wetsuit several times in advance - in the pool and open water.
- Take your health (and swimming ability) seriously.
Triathlon swim deaths