If you’ve ever jumped in the water without warming up and started swimming really hard, you might have experienced rapid heart rate, intense air hunger, labored breathing, and even dizziness, tunnel vision and disorientation. This is not what you want, at the beginning of a swim race, in open water, in the pool, or even at the start of a swim workout. This set of uncomfortable feelings—starved for air, pulse pounding, vision draining away—in no way helps you at the beginning of your race.
You might rather start off your swim at a fast pace, connect with the group you want to swim with, then settle down to a more comfortable, sustainable effort. That can be hard to do when you are gasping and thrashing.
What is happening to create these sensations, and how do you avoid them?
Humans are land mammals. Yet we have adaptations to water, especially in the cardio-respiratory systems. Infants up to six months old reflexively close their airways when their faces contact water. Physiologists talk about the Mammalian Diving Reflex, possessed by many mammals, including humans, and also by ducks, which are not mammals at all, but still have this same reflex.
Mammalian Diving Reflex, according to Ironman finisher, anesthesiologist and acupuncturist Donna Mitchell, M.D., of Timbre Integrated Health, is an automatic response to immersing your face in water. The Trigeminal nerve in your face sends a signal to the Vagus nerve in your heart to reduce your heart rate—and reduce it greatly. This response acts as if you are underwater so you cannot breathe, and you need to conserve oxygen in case you cannot get back to the surface anytime soon. Your pulse rate slows by 10 or more beats per minute and your body shunts blood away from its periphery toward the core—let’s keep the vital functions alive for as long as we can, and hope that you somehow get back to the surface and gulp some air in the next calendar decade.
When you dispense with your swim warm up and just jump in and start swimming, you are creating some wickedly opposing forces. The “Hey! I’m Exercising Here” part of you wants to elevate your heart rate, increase your breathing and deliver blood to your arms and legs. The “Mammalian Diving Reflex I Hope We Are Not Drowning Are We?” part of you does its best to slow your heart rate, retard your breathing and get blood out of your arms and legs so your drowning brain can have some. Which part wins? Who cares? It all feels awful.
There is one small physiological problem with this simple explanation, as all simple explanations of physiological phenomena tend to have. Mammalian diving reflex is only supposed to work when the water temperature is 70 degrees (F) or below. Why, then, does it feel the same when you omit your warm up and just start swimming fast in warmer water? Who knows? Sometimes it just does.
So what do you do to prevent physiological warfare between the competing parts of you as you start your swim?
It’s all in the warm up, Bob.
You’ve been to masters swim workouts when the coach barks, “Okay, 300 warm up,” and everyone in your lane takes off like it’s the Olympics. That’s not a warm up.
A warm up is when you swim slowly, easily, under control and without taxing your system too greatly. Imagine swinging gracefully on a porch swing, mint julep in hand. That’s a warm up. As you get older, you find that you warm up more slowly and need more time during the warm up to find your groove.
Even before you start your swimming warm up, you might consider doing your breathing warm up. You do this by bobbing in the water. Yes, bobbing. As in, bobbing up and down. Take a medium-sized breath, then go underwater and gently, easily exhale for about five seconds. Surface, take in another breath, then go under again, gently and effortlessly exhaling for another five seconds. Repeat this sequence five or six times, for a total of about one minute, before you ever take your first stroke.
Some say this sounds completely goofy. Well, it probably looks completely goofy, but it really works. Compression socks look goofy, too, but they work also so some people wear them. In public. Nobody ever said that triathlon was a beauty pageant.
By gently bobbing for perhaps a whole, entire minute before you start swimming, you settle down your Trigeminal-Vagus nerve cascade, get your Inner Mammalian Diving Reflex part to realize that indeed you are not drowning and you can just calm down. Then you can settle into your warm up (300, no barking, no tearing out like Daytona 500, no Olympics), and settle in.
On race day, make sure you get in the water plenty early. Relax. Float around. Put your face in the water and blow bubbles. Let the water fill up your wetsuit. Swim a few hundred yards. This is especially true when the water is chilly. Everyone knows you want to get into cold water at the last possible minute. At the inaugural HITS race in Palm Springs, CA in 2012, the water was especially cold, the morning dawned raw, windy and chilly, and very few athletes took advantage of the swim warm up. When the starting gun went off, many athletes charged into the frigid water, only to turn around and abandon the race in the first 100 meters. Several were pulled from the water by fully clothed civilian spectators. No warm up, big Mammalian Diving Reflex, much thrashing and gasping. Don’t let this happen to you.
Go ahead, bob. Up and down. That’s right. Just one minute. Try it the next chance you get and see if you don’t feel much more at ease at the beginning and throughout your swim. Your inner Mammalian part will thank you.