Isegoria

Years ago, I made the mistake of going waterskiing for the first time in a cold lake. A really, really cold lake. (I can’t remember, but I think it was late autumn.) When I jumped into the water, my chest seized up, and I couldn’t breath. “Don’t worry about it! You’ll be fine!” Aside from some mild hypothermia, I guess I was fine, but Cold Water Ups Risk of Lung Problem in Swimmers points out that strenous swimming in cold water — 67 degrees Fahrenheit, even in a wetsuit — can cause pulmonary edema:

Strenuous swimming in cold water may cause a life-threatening build-up of fluid in the lungs, the recent cases of three US sailors show.

Navy researchers report that the three men, all in their 20s, accumulated fluid in their lungs during a 2-mile ocean swim in water that was 67 degrees Fahrenheit.

During their swims, the men — all undergoing training as Navy SEALs — developed symptoms that included dizziness, rapid breathing, confusion and coughing up blood.

The swimmers recovered with treatment, but if they had been left untreated, the fluid in their lungs — the mark of a condition called pulmonary edema — would have cut off their access to oxygen, causing them to suffocate.

These cases of pulmonary edema, reported this week in the February issue of the Annals of Emergency Medicine, occurred even though the patients had worn wet suits. They also said they had not put their heads underwater or inhaled water during their swims.

I love the follow-up:

Once patients have recovered, the doctors advise them on how to swim without overexerting themselves, and suggest other ways to reduce their risk of future episodes.

“First, drop out of the SEALs…”

For years we’ve known that severe caloric restriction with adequate nutrition (CRAN) extended animals’ lifespans. Some people even practice CRAN, eating a third less than normal, in an effort to extend their own lives — what we call the “live longer by not really living” plan. According to Leanness, Not Diet, May Be Key to Long Life though, the key may not be near-starvation dieting; it may just be staying lean:

Many studies have shown that animals live longer when they eat, on average, about 30 percent less than normal. The findings have led scientists to speculate that people, too, can extend their lives by dieting.
[...]
Dr. C. Ronald Kahn of the Joslin Diabetes Center at Harvard Medical School and colleagues genetically engineered a mouse that lacked a gene called fat-specific insulin receptor. This change limited the action of insulin on fat cells.

The mice, which they nicknamed FIRKO mice (for fat-specific insulin receptor knock-outs), fed freely without gaining much fat and also lived longer than normal mice.

They had 50 to 70 percent less fat, no matter what they ate, and also were less likely to develop diabetes than normal mice. They lived on average 134 days, or 18 percent longer than normal mice. By the age of 30 months half the normal mice had died but 80 percent of the FIRKO mice were still alive.