•Interval training just got another boost from the New York Times:

[Researcher] Gibala...had a group of college students...ride a stationary bike at a sustainable pace for between 90 and 120 minutes. Another set of students grunted through a series of short, strenuous intervals: 20 to 30 seconds of cycling at the highest intensity the riders could stand. After resting for four minutes, the students pedaled hard again for another 20 to 30 seconds, repeating the cycle four to six times (depending on how much each person could stand), "for a total of two to three minutes of very intense exercise per training session," Gibala says.

Each of the two groups exercised three times a week. After two weeks, both groups showed almost identical increases in their endurance (as measured in a stationary bicycle time trial), even though the one group had exercised for six to nine minutes per week, and the other about five hours. Additionally, molecular changes that signal increased fitness were evident equally in both groups. ... In other words, six minutes or so a week of hard exercise (plus the time spent warming up, cooling down, and resting between the bouts of intense work) had proven to be as good as multiple hours of working out for achieving fitness.

So, as fitness geeks have been saying for a few years now, high-intensity training confers many of the benefits of long-distance work without requiring hours and hours of plodding and pounding.  This is great news for people who find long-distance work boring, and/or are short on time generally, and/or don't mind a little pain and suffering in their pursuit of fitness. 

To my eye, there's something slightly amiss here, though:  'fitness' here is defined as leanness, exceptional endurance, and some adaptations in the mitochondria of muscle cells (check out the whole article).  To my mind, these don't cover the entire spectrum of what constitutes good health and exceptional fitness:  there's nothing about flexibility, strength, joint health, posture, agility, power, balance, athleticism, or any other of the myriad markers of fitness in this study.  

Moreover, there's nothing about which system--if any--is truly sustainable.  Does interval training cause injury?  Does steady-state work cause repetitive-stress fractures?

As always, in measuring fitness, one has to ask, fit for what?  As long as the idea of 'fitness' is reduced to one or two markers, there will always be something missing from the picture.

•Here's another thought-provoker:  that obesity may have allowed us to fight off TB back in the day:

A provocative new hypothesis suggests that in some people, fat not only stores energy but also revs up the body’s immune system. This subgroup may have enjoyed a survival advantage in the 1800s, when people were plagued by a disease that decimated Europe: tuberculosis.


But the heightened immune response that helped some overweight adults survive tuberculosis is now an "evolutionary anachronism" that has outlived its usefulness, said Dr. Jesse Roth...

"Fat is not simply a collection of calories, it is acting like a part of the innate immune system," said Dr. Roth, an investigator at the Feinstein Institute for Medical Research in Manhasset, N.Y. "But this immune system has a downside."

...Yet the question Dr. Roth tries to answer has baffled scientists. The "thrifty gene" hypothesis suggests that evolution favored those who could store fat reserves that helped them withstand lean times, like periodic famines and food shortages.

But that does not explain why body fat carries so many drawbacks, setting off inflammation and metabolic disorders like insulin resistance, high cholesterol and atherosclerosis.

I'm no fancy evolutionary biologist, but I imagine that real obesity such as is epidemic today is probably a fairly modern phenomenon, simply because at no time else in history has such a large portion of the population been so sedentary AND had such easy access to calorie-dense food. 

There was a time, after all, when feeding oneself cost calories.  It wasn't just a matter of wheeling your SUV through the drive-thru:  you had to track down an animal or plant a crop.  The food you consumed was a reward for the physical labor of finding or hunting or growing that food (could this be part of why a post-workout meal tastes so good?).

Perhaps the gene for obesity was indeed effective in fighting off certain diseases and for keeping one alive during lean periods.  But back in the caveman days when these genes were evolving, I imagine that food was scarce enough that even Joe Caveman with the "fat" gene never really got fat.  He would have had to be exceptionally active by today's standards just to stay alive, after all:  running down prey and avoiding predators, migrating to fertile areas during winter months, and later, planting crops and tending fields.  Sitting around on the couch--or the comfy rock, perhaps--just wasn't an option. 

So back then we might have had a bunch of hairy strong guys carrying the fat gene who weren't fat.  They got all the disease-fighting, life-sparing benefits of having a 'thrifty' metabolism but weren't saddled with all the downsides of actuelly being fat which are so prevalent today.  So they lived long enough to reproduce, and eventually, their genes spawned our current generation of couch-dwelling, fast-food snarfing denizens.  

Anyone else have a theory?