The audience, clad in warm winter coats, erupts in cheers as the swimmers dash into the ice-cold water of the green lake.
This is ice swimming, and it's more than dipping a toe into your local outdoor pool. These events take place in water colder than 41 degrees Fahrenheit (5 degrees Celsius), and you won't see anyone in a wetsuit.
"I love ice swimming competitions," she said. "I just love being outdoors in the fresh air. There is a sense of energy and a sense of life."
There are ice swimming events wherever there's a cool stretch of water: Russia, South Africa, the United States and Scotland are just a few countries that have hosted races.
"It's almost like the water is denser and I can feel it all down my arms and on my legs, and when I kick against it, it feels heavier than in a warm swimming pool," Campbell said. "I think that feeling, that sense of being in nature in that moment, on the edge is really exhilarating,"
The benefits of getting cold
With over 40 countries having branches of the International Ice Swimming Association
, it is clearly becoming a popular sport, offering a dose of adrenaline and adventure.
"Usually, I feel fantastic. I get a huge buzz ... a sense of elation, and I just want to do it again. I definitely have a sense of energy, a sense of life, a sense of purpose. It's a definite mood-lifter, no question," Campbell said.
In addition to the adrenaline rush, early studies
suggest that cold-water swimming could be a treatment for depression, as it activates the sympathetic nervous system and increases blood levels of noradrenaline and beta-endorphin
, which play an important role in the functioning of the heart.
Ice swimmers may also experience an endorphin rush, in which feel-good chemicals are released, says Dr. Jonathan D. Packer, an assistant professor of orthopedics at the University of Maryland School of Medicine
. He explained that this could be good for helping to treat mood disorders, adding that endorphins release stress, with a variety of health benefits.
"While the specific effects, the benefits of ice swimming haven't really been studied in a scientific manner, we can certainly look at other types of cryotherapy for any perceived benefits," Packer said.
Cryotherapy, the application of extremely cold temperatures to the body, is often used by athletes who submerge themselves in ice-cold water for about 10 minutes. Packer said research shows that this can decrease inflammation, promote healing and improve circulation.
"I know that many of the ice swimmers have had some anecdotal evidence -- that it can improve their cognitive abilities; they say it improves their energy; some people even say it helps their libido," Packer added. "There's also been some reports from patients with chronic pain conditions that have reported having improved pain from those conditions after starting ice swimming."
In terms of exercise, ice swimming could feel like an extra-arduous workout. Packer noted that "a potential benefit is that you burn more calories than regular swimming. Not only does your body have to work just as hard to swim from point A to point B, but it also has to work harder to keep your body temperature up."
Not all fun and games
Despite some potential benefits, ice swimming can be a risky activity for rookies, so don't go jumping into a freezing pool without some supervised practice. In this kind of sport, proper training is essential not only to success but to survival.
"Someone might be able to swim 10 to 12 hours in water that's 16 or 17 degrees (Celsius), and they are swimming 20 minutes in water of this temperature," said Dr. Ruth Williamson, who led the medical team at the ice swimming event at Loch Lomond.
"This is something you train for. You get your body used to getting in to the cold water and get over that cold shock," she said. With training, a competitor's muscles adapt to a lower blood supply so they can keep that muscle effort going longer.
Campbell says she tries to swim five days a week in very cold water, as well as normal club swim training two or three days a week, plus Pilates and yoga at least twice a week.
Regular icy swims allow her body to acclimate or learn to navigate potential dangers such as hyperventilation, high blood pressure and hypothermia.
This could be life-saving, as plunging into icy water unprepared can lead to a strong gasping response -- a reflex that can result in drowning.
"Initially, you have this shock, and people will take a couple of large breaths. It's important not to panic at that time, because you can accidentally ingest water. It can be dangerous, and you can drown," Packer warned. "The most common source of death from being in cold bodies of water are the cardiac arrests from this cold shock response."
The low temperature also makes the blood pressure rise, leading to fast breathing, and there's a risk of hypothermia.
Even out of the water, there's a risk of the body temperature dropping even further, so it's important to be monitored for an hour or so after a swim, Packer said.
"This is definitely not something to try by yourself. All of the ice swimmers often start swimming in the summer and gradually acclimatize," Campbell said.
(Don't) dive right in!
If you want to give cold water swimming a try, start with regular outdoor swims in the summer months and build up to those chillier seasons.
It's also best to enter slowly rather than diving in if the water is under 15 degrees Celsius
, though this may come as a natural instinct anyway, to counter the body's gasp reflex.
And swimming in icy water is not for the faint-hearted -- literally. If you have heart problems or pre-existing medical conditions, you should seek advice from a doctor before swimming, Packer said.
But if you're feeling brave, ice swimming could open up a world of icy-fresh possibilities, lifting your mood, helping friends and offering a unique form of exercise.