SIPE: Description, Research and Prevention

SWIM-INDUCED PULMONARY EDEMA

As a coach and an athlete, I have been curious about this phenomenon since I became aware of it.  I've been in multiple races where an athlete has died during the swim, and it's always been very sad but also mysterious as to why an athlete in good condition might experience what is normally attributed to a heart attack in the water.  It turned out some years ago that there was a little understood and rarely researched condition that military divers were experiencing called IPE.  Later, after more research, the name was changed to SIPE.  

The problem with SIPE is that it doesn't exhibit symptoms that are readily identifiable and these symptoms can be easily dismissed, but if ignored, can lead to death.  If the athlete stops swimming and rests, the symptoms often clear up spontaneously.  That can lead to dismissal of the concern and possibly recurrence and serious consequences later.  

WHAT IS IT? 

This issue occurs when fluid enters the alveoli of the lungs and essentially prevents oxygen transfer to the blood.  

This article from August 2023 Triathlon Magazine describes the reason that has been determined by researchers for this to happen. 

This article from The Dive Lab  also explains it.  The Triathlon article is pretty long but details the history of the research and how researchers are gathering data using actual athletes.  

SYMPTOMS

Symptoms include shortness of breath, a rattling or phlegmy cough, and fatigue.  Many triathletes, trained to ignore pain and push on, will do the same with these symptoms.  It's easy to brush them aside as being caused by a tight wetsuit, panic, overtraining, etc.   If you stop to cough up the phlegm with SIPE, it will be pink or bloody.  Most triathletes, focused on finishing the swim, will not stop long enough to examine their spittal, but this could save your life.  If you have these symptoms, get out of the water, your race should be over.  Find a kayak or buoy and request help to get back to shore.  

• Shortness of breath or rapid, heavy or uneven breathing
• Uncontrollable coughing. This cough is usually distressing and can produce pink, frothy, or blood-tinged sputum (originating in the lungs or bronchial tubes)
• Confusion or irrational behavior
• Tightness or pain in the chest
• Difficulty breathing at the surface
• Crackles, rattling, or junky feelings deep in your chest
• Wheezing

WHY DOES IT HAPPEN? 

The article in Triathlon Magazine discussed many of the underlying causes that have been researched.  It can happen to anyone, even without underlying causes, but there do seem to be some reasons it can happen.   Here are a few that have appeared to be factors: 

• Cardiac disease and high blood pressure
• Increased stress and exertion during immersion
• Immersion in cold water
• Excessive pre-hydration before immersion
• Antiplatelet agents such as aspirin or fish oil
• Using a snorkel

Researchers are finding that elevated blood pressure can be a significant factor rather than conditions that presage a heart attack.  High blood pressure, along with exercise and cold, can cause the body to shift circulation efforts to the core, causing blood pressure to elevate further. This can cause the barrier in the alveoli to be overcome, forcing blood into the lungs. Essentially, the athlete can drown in their own blood.  

CAN WE PREVENT IT? 

Researchers in Norway, using athletes competing in the Nordic Man race, found that Viagra, developed to reduce blood pressure and open capillaries, (the ED usage was a side benefit that was capitalized on by the pharmaceutical company) can be used prophylactically to reduce the risk of SIPE. While this seems somewhat effective, they found that not all athletes, even when screened prerace, can be identified for SIPE risk. During the Mont Tremblant race, researchers worked with Ironman to develop a predictive survey and protective swim protocol to identify, locate, and support athletes in the swim. Prior to the swim they gave special yellow caps to those athletes that appeared to have the risk of SIPE. They then used drones, one per each of the 25 racers, to watch their swim. During the race, none of those identified as having this risk had any problems, but the drone operator spotted another racer in distress and they were able to get help to that swimmer and prevent disaster.  

If you have had these symptoms in the past, it might be a good idea to visit your doctor and determine if you have elevated blood pressure or any of the identified possible underlying issues and get treatment.  

Educating yourself about this condition is another way to prevent it.  

Finally, you may want to find out if there are studies near you that you can participate in to help triathlon and your fellow triathletes swim more safely.  

The Value of Off Season....Maintenance training

I strongly encourage my athletes to take a serious break from training in December. The pros do, so why are you still training like there's an IM next week? If you're afraid of losing fitness, you can actually maintain your fitness with a lot less training than you do to prepare for a big race. So while I don't recommend a total break from training, I DO recommend you back down your training hours and training stress to a level that could feel minimal to most IM athletes. I understand. It can be hard to not train when you have a habit of going to the gym. My best advice is to keep going so you still have that habit, but to slow down, do more zone 2, reduce the time at the gym and generally focus more on enjoying the workout than on pushing your limits. There will be plenty of time for pushing limits once you get back onto the race prep planning. Another way to back down is to take more rest days per week. If you've only done 1 per week, take 2. Older athletes may train with 2 days of rest so adding a 3rd rest day will be necessary.

 

If you cannot fathom adding a day of doing nothing, change from a bike or run to an easy hike or a yoga class...not Iyengar or Hot Yoga, but more like meditative yoga for mental and physical rest and recovery. In essence, give yourself time to read a book, be bored, spend time with the family, or generally focus on anything else for a while. The hazard of continuing to train is that you burn yourself out before the race training plan begins because you've made your training into a second job instead of a break from work. IM training can feel like you're working the second shift at its peak. This taxes you mentally and physically, and continuing this without a break can break you and cause you to feel unmotivated and unjoyful when workouts appear on your Garmin or training plan.

 

Letting the biochemical adaptations of training clear, and then waiting for the season to bring them back, gives us a racing jolt. Otherwise, we'd cruise around at 75% of our capability all the time. This is why detraining in the off season allows us to peak for races. (From The Benefits of Taking and Off Season,Trevor Connor, Fast Talk Laboratories). 

If you use training peaks, look for a form # that is 0 or slightly positive. That means you are in a maintenance phase.  Negative form means you are building, but you need to save that for when you are training for your races. Ask your coach to help you figure out what to reduce to get Form to a 0 level. 

On tridot, go to your settings and set all your sports to LOW intensity. This will reduce your training plan sets and the training intensity to more of a maintenance level. You can ask your coach to help you with that if you can't find it. Thus you can keep working out, but your focus and intensity is lower for about a month to 2 months. Enjoy the time. Think about how you will fill in the extra hours you gain from less training. What books have you put off? What plays or movies would you like to see? What family events can you schedule? Your body may feel a bit jittery with less training, but like anything we adapt. Your mind will appreciate the break from the high demands of life, work, and training, and your family will certainly appreciate that they have your full attention for the holidays. 

If you're worried about fitness losses as you reduce your training, check out this article that says it is a good thing to lose some fitness and destress. DESTRESS and DETRAINING If you don't have time to read that article (YOU SHOULD...YOU'RE NOT TRAINING SO HARD NOW! lol), Here is a quote that should reassure you that your detraining levels will not impact your future outcomes as much as you may imagine. "Structural improvements such as capillary density, muscle fiber ratios, and the size of our hearts do not detrain quickly. Many studies have shown no changes even 12 weeks after stopping exercise. In fact, one study demonstrated that many well-trained endurance athletes still had larger hearts 14 years after retiring."

Here's an article from another coach about why resting and losing some fitness is a good idea in the off-season. REST SEASON GREETINGS In conclusion, give yourself a break. Take a few more naps, and rest assured you will be better served by doing that now than by continuing to push yourself for the next 6-12 weeks. In fact, putting more relaxation in your life can be a significant benefit in the long run. And that's what we're training for, right? The LONG RUN? I know I'm embedding a couple of lame puns but bottom line I hope is that you get it. Giving yourself, your family, and your friends time to reconnect and enjoy life is a good way to celebrate last year's training, racing, and the season. HAPPY HOLIDAYS TO ALL MY FRIENDS AND ATHLETES.