Monday, December 30, 2013

Intermittent Fasting Beats Traditional Diets

  • Intermittent fasting or “scheduled eating” is a powerful strategy for shedding excess weight and reducing your risk of chronic diseases like diabetes, heart disease, and cancer
  • Three major mechanisms by which fasting benefits your body include increased insulin sensitivity and mitochondrial energy efficiency; reduced oxidative stress; and increased capacity to resist stress, disease, and aging
  • A recent human study confirmed that intermittent fasting was actually more effective for weight loss and improving insulin resistance than daily calorie restriction
  • Intermittent fasting can also dramatically boost human growth hormone production, reduce inflammation, and lessen free radical damage—all of which have beneficial effects on your health
  • To get started, consider skipping breakfast, and avoid eating at least three hours before you go to sleep. This should effectively restrict your eating to an 8-hour window or less each day

I have been doing IF to some degree or another for 3 years, and have found it is powerful for many reasons.  One is it just breaks the habit of eating all the time.  Two, it proved I don't have to eat all the time to "get enough food" to perform well in workouts.  There's no downside, no risk, and no cost - for most folks.  Start easy - push the breakfast back by hourly increments, and have good food on hand in case you "crash".

Good advice:
In order to understand how you can fast daily while still eating every day, you need to understand some basic facts about metabolism. It takes most people eight to 12 hours for their body to burn the sugar stored in your body as glycogen. Now, most people never deplete their glycogen stores because they eat three or more meals a day. This teaches your body to burn sugar as your primary fuel and effectively shuts off your ability to use fat as a fuel.
Therefore, in order to work, the length of your fast must be at least eight hours. Still, this is a far cry from a 24-hour or longer fast, which can be quite challenging. I believe that, for most people, simply restricting the window of time during which you eat your food each day is far easier.
For example, you could restrict your eating to the hours of 11am and 7pm. Essentially, you’re just skipping breakfast and making lunch your first meal of the day instead. This equates to a daily fasting of 16 hours—twice the minimum required to deplete your glycogen stores and start shifting into fat burning mode.

Saturday, December 28, 2013

Why do people hate CrossFit? — I. M. H. O. — Medium

To to a CrossFit box and see their workout of the day. Can’t do it? No problem. Any trainer at any box anywhere in the world will help you scale it, teach and reteach you the motions, and even come up with alternative movements if you are limited. The one thing that won’t happen is to have someone tell you that you are weak or giving up. They may encourage you to try to push yourself a bit more once you start to feel comfortable. That’s called progress.That’s called a challenge.
My favorite moments in CrossFit are watching the fifty-two year old mom of three who’s forty pounds overweight shout in triumph as she finishes her (scaled — gasp!) workout knowing she pushed a little harder this week than last on her path to health and fitness. This time, she ran each part of the running elements rather than walked, and that is a truly beautiful thing.

I enjoyed this article, which puts a finger on why the CrossFit backlash can be so angry.

Thursday, December 26, 2013

Wheat Threatens All Humans, New Research Shows - The Daily Beast

All grains produce lectins, which selectively bind to unique proteins on the surfaces of bacteria, fungi, and insects. These proteins are found throughout the animal kingdom. One protein in particular for which WGA has an extremely high affinity is N-Acetylglucosamine. N-Acetylglucosamine richly adorns the casing of insects and plays an important role in the structure of the cellular walls of bacteria. More importantly, it is a key structural component in humans in a variety of tissues, including tendons, joint surfaces, cartilage, the lining of the entire digestive tract, and even the lining of the hundreds of miles of blood vessels found within each of us.

It is precisely the ability of WGA to bind to proteins lining the gut that raises concern amongst medical researchers. When WGA binds to these proteins, it may leave these cells less well protected against the harmful effects of the gut contents.
WGA may also have direct toxic effects on the heart, endocrine, and immune systems, and even the brain. In fact, so readily does WGA make its way into the brain that scientists are actually testing it as a possible means of delivering medicines in an attempt to treat Alzheimer’s disease.

It's hard to know how real these "may" statements are, but once I committed to near elimination of wheat from my diet, I'm glad I have.  The changes from wheat elimination were subtle, and the changes in my health over the last 6 years have been profound, and I'm not sure which health changes to attribute to which food changes.  All I can say is it is certainly a thing to be concerned with and to experiment with if your health is not what you wish it were.

Tuesday, December 24, 2013

Tips for Proper Weight Management This Holiday

  • The average American gains close to one pound during the six-week period from Thanksgiving through New Year’s Day, while those who are overweight or obese gain an average of five pounds
  • Simple tips, such as planning out what you’ll eat at the start of each day, eating your protein at the beginning of your meal, going for a walk or reprograming the way your brain responds to high-sugar foods can help keep your weight in check
  • Intermittent fasting can also help you avoid weight gain and also normalize hormones related to weight and metabolism, such as insulin and ghrelin
  • Achieving and maintaining your ideal weight isn’t something to think about exclusively during the holidays; it should be more of a year-round consideration

Monday, December 23, 2013

It's the Reporting, Stupid

Meanwhile, bears have figured out how to be healthily obese and then lose massive amounts of weight without problems.
"I want to learn how the grizzly bears work their magic," Dr. Kamb says.
Dr. Corbit, who says he had worked "exclusively on mice" before joining Amgen in 2011, says his studies of fat and blood samples suggest the bears respond to excessive weight gain differently than many people.
The bears seem to adjust their sensitivity to the hormone insulin that controls how much the fat and sugars in food are broken down and stored for energy. The bears are more sensitive to insulin while putting on pounds for hibernation. When hibernating a few weeks later, the bears shut off their insulin responsiveness entirely.

Oh, the embarrassment of the researchers after reading this.  Humans are sensitive to insulin when they are healthy.  Humans likely become insulin resistant when fasting too, we have many of the same mechanisms as animals that hibernate.  The question, unless you are looking for a new drug, is "what is it that makes the exquisitely well adapted human mechanism for storing and losing fat go wrong such that people can be fat, feel lethargic, and be hungry when they are not calorie deprived?"

However, the article isn't really supposed to be an enlightening piece about fat loss and health, it's supposed to be about the fascinating idea that we may be learning from bears.  Reporters generally don't seem to know enough about metabolism to write informative articles, but it's easy to entertain with a piece written about bears.

Saturday, December 21, 2013

Derrick Rose, Rob Gronkowski, and the Rise in ACL Tears - Grantland

Dr. Robert Litchfield, medical director of the Fowler Kennedy Sport Medicine Clinic at the University of Western Ontario and part of the Canadian Alpine Ski Team medical group, studied videotape of ACL injuries and found a pattern. He found that those who tore their ACLs all did the exact same thing with their legs when they were avoiding a defender or reacting to an offensive player. "They throw it [the injured limb] out to the side, and they try to make an upper-body move where they move away from the side that they've just planted," he says. "And they get to what we call a `point of no return.'" The knee misaligns, turns inward, and the athlete lands knock-kneed. That is when you hear the pop. That is why, Dr. Litchfield believes, an athlete like LeBron James will never suffer a tear. "When he comes down from a dunk, he comes down very low and powerfully versus coming down on an extended leg." In short, LeBron's legs are bowed, and athletes who bow their legs generally don't tear their ACLs.

This one is a very personal issue for me - tore my ACL in 1989.  I was going over the 8 foot wall, came down a bit awkwardly and the sand under my left foot shifted.  The "POP" they reference in the article - yeah, it's wild.  You know in a moment that something is not right.  Weirdly they did not diagnose my blown ACL right then, which resulted in several pivot shift injuries over the following years.  Then in 1992, not knowing my knee was unstable, I tried skiing.  That quickly lead to a nasty tear of the meniscus.  With the meniscus tear and no ACL, my knee was so unstable that I couldn't walk a quarter mile without knee pain.  Not good.

I finally talked the Navy into a repair in 1995, and my knee has generally improved every year since then.  In 2007, I got to a point that I could no longer run more than 3 miles or so.  Then, I began CrossFit, and the resulting gains in hamstring strength, range of motion, and movement skill (running using the POSE method, and no longer heel striking, was a big help).  POSE walking also turned out to be a huge help - when I used to walk with long strides, and a fully extended knee on each step, my knee would fill with fluid.  The resulting Baker's cyst would swell and be painful for days.  Using the POSE ideas of never extending the knee, and instead, using gravity to help one fall off of the foot that is underneath you, I can walk without fear of pain.  My latest test was a 13 miles hike in mountain of Utah with about 30 pounds of gear, up and down at ~6500 MSL.  The next day - nothing!  It was awesome.

There are several elements of knee injury.  I thought the quote above was the most telling in the article, because it points to body position as the most significant factor in ACL injury.  I think we will see athletes who are taught solid positioning through CrossFit and CrossFit Kids will see reduced incidence of ACL injury.  Additionally, since the hamstrings help the ACL position the body and the knee (tight hamstrings pull the tibia towards the hip, reinforcing the ACL's work of preventing the femur from sliding off of the back of the tibia), those who are strong in the hamstrings from skillful work with squats and deadlifts will have an advantage in injury prevention.  Athletes can do amazing things with quad dominant squats and deads, but in the end, that's a poor movement pattern and there will be a price to pay.

The other issue with ACL tears is glycation - those who continually bomb themselves with high sugar diets create weak, glycated tendon attachments which fail at lower stresses.  I think CrossFit and CrossFit Kids athletes who avoid this dietary time bomb will reap the benefit in this way also.

Thursday, December 19, 2013

Mercola - Fructose and Cancer

Studies have shown that different sugars are metabolized using different metabolic pathways, and this is of MAJOR consequence when it comes to feeding cancer and making it proliferate. Three years ago, researchers published findings showing that fructose is readily used by cancer cells to increase their proliferation.6 Cancer cells did not respond to glucose in the same manner.
In this case, the cancer cells used were pancreatic cancer, which is typically regarded as the most deadly and universally rapid-killing form of cancer. According to the authors:
"Traditionally, glucose and fructose have been considered as interchangeable monosaccharide substrates that are similarly metabolized, and little attention has been given to sugars other than glucose. However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters.
Here, we report that fructose provides an alternative substrate to induce pancreatic cancer cell proliferation. Importantly, fructose and glucose metabolism are quite different; in comparison with glucose, fructose... is preferentially metabolized via the nonoxidative pentose phosphate pathway to synthesize nucleic acids and increase uric acid production.
These findings show that cancer cells can readily metabolize fructose to increase proliferation. They have major significance for cancer patients given dietary refined fructose consumption, and indicate that efforts to reduce refined fructose intake or inhibit fructose-mediated actions may disrupt cancer growth." [Emphasis mine]

Sunday, December 15, 2013

Double Under Instructional

Nice video of Dan Bailey teaching the double under:  mov

All the elements:
Body position - just like the POSE running position; soft knees, belly tight, butt tight, weight on forefoot

Feet close together

Jump = just slightly more vigorous than a single under - jumping too hard/high usually leads to bad position and from there to wasted effort and many missed jumps.  Most folks want to jump higher to get a double under.  Instead, move the hands faster.

If the knees bend after the rebound (IOW, pulling feet high to "make room" for the rope), or the body breaks at the waist, you are making this harder

Hands - move the hands with the wrists, elbows/shoulders should move little

Experiment with hand width - wider hands makes the rope "shorter" and faster, which can be bad or good

Hand position forward/aft - play with this but if you can't figure out why you are missing all of a sudden, this is probably it.

Slow bounce, as high as you can without distorting body position
Low bounce as fast as you can - slowly increase the tempo as you work towards 100 hyper fast single jumps
A double under is a slow, slightly higher bounce with the super fast hands.  If you try to jump high and fast, it don't work so great (unless you have hands like Chris Spealer or Buddy Lee!).

This is a high skill movement, and it is a decent question whether the time invested to learn it provides benefits equal to the investment.  Bouncing on the balls of the foot with balance and precision when gasping for breath is a good thing.  Correct body position over the balls of the feet is a good thing (carry over to running).  The ability to play with moving the hands at a different tempo than the feet is a good thing.  Being able to stabilize the torso while bouncing and gasping for breath is a good thing.  Being able to express this degree of skill when exhausted is a grand thing.

And doing double unders - it is just plain fun when you hear the whip of the rope and the double slap on the ground.  The glorious ecstasy that one finds when on a run of 10-40 DUs and also dead tired - the mind wonders how one can't miss the next jump.  The mind stops trying to control the DU and just lets them happen.  The body drives on until the mind takes back over at extreme muscle fatigue.  Crazy to be on that ride.

Friday, December 13, 2013

The Trouble with Snooze Buttons (and with Modern Sleep) : The New Yorker

Fortunately, the effects of sleep inertia and social jetlag seem to be reversible. When Wright asked a group of young adults to embark on a weeklong camping trip, he discovered a striking pattern: before the week was out, the negative sleep patterns that he'd previously observed disappeared. In the days leading up to the trip, he had noted that the subjects' bodies would begin releasing the sleep hormone melatonin about two hours prior to sleep, around 10:30 P.M. A decrease in the hormone, on the other hand, took place after wake-up, around 8 A.M. After the camping trip, those patterns had changed significantly. Now the melatonin levels increased around sunset—and decreased just after sunrise, an average of fifty minutes before wake-up time. In other words, not only did the time outside, in the absence of artificial light and alarm clocks, make it easier for people to fall asleep, it made it easier for them to wake up: the subjects' sleep rhythms would start preparing for wake-up just after sunrise, so that by the time they got up, they were far more awake than they would have otherwise been. The sleep inertia was largely gone.

Thursday, December 12, 2013

Mercola - Sugar Feeds Cancer?

"The study confirms the old adage that sugar feeds cancer because they found that tumor cells do thrive on sugar (glucose). However, the cells used fructose for cell division, speeding up the growth and spread of the cancer. This difference is clearly of major consequence, and should be carefully considered by anyone who is currently undergoing cancer treatment or seeking to prevent cancer.

"This does not mean you should avoid fruits, the benefits of most fruits outweigh any concerns to fructose. I would suggest to not juice your fruits and to eat them whole, and also realize we have bred many of these fruits to a very high level of fructose. Fruits today are many times sweeter than they were historically, and should be consumed in moderation.

"The real problem is the high fructose corn syrup that is added to practically every processed food and drink you see."

Saturday, December 7, 2013

Science, Diet, Health, Cognitive Dissonance, Opinion and Humility

Dr. Mike Eades of is blogging again and that's good for me, I have learned quite a lot over the years from his blog.  If he's overly contemptuous from time to time, he's also very skilled at teaching the scientific method as applied to health and diet.  There were a couple of posts that completely changed how I see human metabolism.  Thanks Mike!

In this post, he discusses the challenges in the business of helping people sort out dietary right from dietary wrong.  The title - Eat Less Move More and Die Anyway - points to the oft cited formula for how to change the world's predicted health care disaster (if everyone is sick, you can't pay for all the necessary meds and care).  The benefit of this simple approach is it is not intimidating - you might think "anyone can do this, even me."  The downside - the science that is available indicates that moving more and eating less does not help you dodge those nasty terminal endpoints of life that we would like avoid so that we can live long enough to die in our beds (as we used to say when I was a Patrolman trying not to get killed in the line of duty).  At the link above he details a 9 year study which proved fairly convincingly that a low fat, low calorie intervention with moderate exercise was not effective at combatting the diseases of civilization.

Not that you would have heard about that 9 year study, because if they mentioned that, they'd have to start saying things like "we never really knew whether low fat, low cal was good for you or not, but we were sure hoping it would be.  Sorry about all your dead relatives and all those meds you are taking to help with hypertension, gout, and diabetes."  As to that point, one might be concerned that government health care authorities made recommendations that may be killing us, and may be making us sick and at the same time enormous consumers of the medications that sick people get in this country, AND that those recommendations were not proven by science.  The implications are immense, but that's another discussion.

Nor were you likely to have heard about these studies, which could have changed the debate all by themselves (these quotes are also from Mike Eades' blog):

"A couple of years ago, Ron Krauss, as mainstream a researcher as you could find and holder of all sorts of academic credentials, started thinking that maybe saturated fat wasn’t the demon everyone thought it was. He dug up all the studies he could find looking at whether or not saturated fat actually did cause heart disease. He put all these studies together in a meta-analysis, and got it published in the prestigious American Journal of Clinical Nutrition (AJCN). The article, titled Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease, came to the following conclusion:
there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.
"And, as if to rub salt in the wounds of the lipid hypothesis folks, Krauss published another paper in the same issue of the same journal looking at a nutrient that often replaces saturated fat.
"This second paper, titled Saturated fat, carbohydrate, and cardiovascular disease, concluded
there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate. Furthermore, particularly given the differential effects of dietary saturated fats and carbohydrates on concentrations of larger and smaller LDL particles, respectively, dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity.
The point Mike Eades is grinding on is the abuse of the mantle of science by the combination of the "gurus" and the science journalists, who should know better than to simply babble on about the results of studies that, almost always, can't show cause and effect, but are treated as if they do.

You can see the resulting cognitive dissonance here, where Forbes reviews the book Grain Brain:
Some in the nutrition and medical communities take issue with Perlmutter’s premise and prescription. Several critics, while not questioning the neurological risks of a high-carb diet, have pointed out that readers may interpret his book as a green light to load up on meat and dairy instead, a choice that has its own well-documented cardiovascular heart risks.
“Perlmutter uses bits and pieces of the effects of diet on cognitive outcomes — that obese people have a higher risk of cognitive impairment, for example — to construct an ultimately misleading picture of what people should eat for optimal cognitive and overall health,” St. Catherine University professor emerita Julie Miller Jones, Ph. D., told the website FoodNavigator-USA.
If it is so dangerous to load up on a meat and dairy based diet, which of course is not what low carbers typically advocate, why can't they show one single intervention study in which people eat that way have poor mortality results?  Answer - because when people are put on a diet like that they don't get sick.  The thing that's not there can be ignored by those who still believe what has never been true.

Science is supposed to be about conflict, because the scientific method is fundamentally about the human condition.  Humans are not good at doing truth.  Humans are subject to all kinds of bias.  Being a scientist does not cure one from being human.  Thus, the first response to all scientific efforts should be to think "that's BS, how could they prove that?"  Perversely, we consult scientists and ask them their opinions as if that's the same as the scientific method.  Things that scientists say are judged authoritative.  This leads to the "You are an idiot and I'm a genius" argument that is all over the web, in which a person grades their own homework and tells the world how they know the science like no other.  It is certainly tough to get a blog audience by saying, "gee, we don't really know, but this is what I think".  When science is conclusive - drop an apple, it falls, debate about gravity over - we don't have much to fight over.  The presence of web-fighting about something is evidence of weak science.

Because the science of diet and health is so immature, humility will serve one well.  Rather than pretending to know what isn't known, I think it's more useful to focus on what works - for yourself, for your clients, while continuing the search for truth.  Human nature gets in the way of this approach, ego demands we proclaim our intellectual victories and pummel the ignorant authorities proved wrong daily, but that's the struggle of being human.  As it seems to be for Mike Eades, it is hard for me not to feel contemptuous and angry about folks who should know better, who hold positions of authority in government and as industry leaders, who say "this is true" when, based on the scientific method they claim supports them, "this may or may not be true."

What I think, and what has worked for me, is that excess blood sugar is the worst thing one can do to oneself if the goal is to avoid early decline, physical and mental degeneration, and the diseases of civilization.  The best way to regulate blood sugar is to avoid destroying your body's ability to regulate it for you.  The body has an ancient mechanism that works well when not bombarded by too much of the agricultural monsters we produce for ourselves today (primarily sugar and wheat, with industrial seed oils playing a role via enhanced inflammation). You will die one day, I will die one day, the point is what do you get to make of the days you have before that terminal end point?  The sick have fewer choices, and the sick take choices away from the ones that they love.  Striving for thriving health is the shizzle, I think, if shizzle still means what it did the first time I heard that ten years ago.  My conjecture may not work for everyone.  My conjecture has quite a bit of supporting evidence in the scientific literature but is far from proved true (although may be able to do something about that before I reach my terminal end point).

You can test this conjecture on yourself with ease.  If you restrict carbs with a well formulated high fat, moderate protein diet, does your blood sugar regulation improve?  Do you have less hunger?  Can you start to win the battles with your food obsessions?  Does real food begin to taste better?  Do your aches and pains feel less achy?  Are you sleeping more soundly?  Is your belly getting smaller?  Has the government stopped recommending foods that used to make you fat, lazy and sick?  (Just kidding on that last part, that's not going to happen anytime soon because they haven't exhausted their ability to try to prove what they said was proven 40 years ago).

So don't take some blogger's word for it, or some person's word for it who has a PHD after their name.  Do the experiment on yourself, the results can be (if the experiment is done correctly) more significant than a lifetime of expensive science performed by folks who you never met.

Tuesday, December 3, 2013

PN: Food Is Fuel ... And A Lot More

PN writes about their concern that fitness folks can only talk about food in term of it being fuel.  Why does that bug them?
Food is so much more than “fuel” or “energy” or “calories”.
For one thing, even if we’re looking at food purely in terms of its physiological effects, when we focus on “energy” and “calories”, we’re only telling part of the story.
Sure, the macronutrients (proteins, carbohydrates, and fats) in food contain “energy” or “calories”. Or, perhaps most correctly, “chemical bonds that, when broken, are used to create ATP”.
But food also includes micronutrients, phytochemicals, zoochemicals, water, and more.
Think of these as character actors in a movie. They may not be the “stars” of the show. They don’t really provide “energy” (or fuel) at all.
Yet their dynamic interactions create the spark. They’re absolutely critical for energy, performance, mood, and optimal long-term health. In other words, without them, the show won’t go on.
Unfortunately, the “food as fuel” story almost completely ignores these important characters.

My dearly deceased martial arts instructor and mentor used to reminisce about his instructor/uncle taking him to Star Wars, many times, usually late at night, and saying "Dis good part!"  Which is what this is:
Okay, so here’s the thing: Living organisms are not machines.
Rather, they’re incredibly complex, self-regulating, and dynamically steering. Frankly, they’re almost magical systems.
If you’ve spent any time doing “calorie math”, you’ll know that trying to calculate precise inputs and outputs is frustrating.
Perhaps you ate more calories than you thought you should… but got leaner.
Or you ate fewer calories than you thought you should… and gained weight. (Or you didn’t lose that last stubborn 10 pounds.)
Or you started eating breakfast instead of skipping it… and dropped a couple of inches off your waistline.
According to the simplistic “food as fuel” view, none of this should be possible. Yet it happens all the time.
Because human bodies aren’t combustion engines. They’re complex, dynamic, organic, and infinitely sensitive systems.

Sunday, December 1, 2013

Going Up?

The people who struggle learn the snatch – or really perform any overhead lift – are generally adults.  Why?  Because they've lost a fundamental movement pattern – overhead reaching – that everyone should have!  Barring some developmental disorder, everyone has the ability to get the arms overhead when they are kids, whether it's to reach for the cookie jar or to climb on the jungle gym at the playground.
Think about it: the overwhelming majority of teenagers can learn to Olympic lift in a matter of a few weeks or months.  And, it's been discussed time and time again how Eastern European kids would practice Olympic lifting patterns with broomsticks to maintain these crucial movement patterns to prepare for the day when they'd load them up.  They understood this very important lesson:

It's much easier to maintain mobility than it is to lose it and try to get it back.

This isn't just because tissues can become fundamentally short and degenerative.  And, it's not just because resting posture becomes more aberrant or individuals accumulate more wear and tear.  It has a lot to do with the plasticity of the human brain.  Just like it's a lot easier to train a puppy than it is to teach an old dog new tricks, it's much easier to shape the neuromuscular patterning of a developing child or teenager than it is to change the more concrete patterns of an adult with poor movement quality – especially when that adult insists on trying to learn the pattern with 65 pounds or more on the barbell (rather than just a broomstick) – and after years of sitting at a computer.

This was one of the revolutionary things about CrossFit.  I always worked out in one way or another, but CrossFit punished lack of mobility and rewarded improvements in mobility.  Thus, working to regain lost mobility wasn't the stuff you "should" do, it was what I wanted to do in order to get closer to my performance goals (with less pain!).  Doing the "right" thing is a whole new deal when it is in the context of better performance, instead of just time spent doing stuff that may or may not change how to your work/play/live.  I'm still not all eaten up with doing all the mobility work I could do, but one example that stands out is how much change I can see when I squat.  At age 49, I can squat to near full depth, cold.  At age 42, I could not squat to parallel, even with a warmup.  The implication of this regeneration of natural mobility when doing hard work is significant - better performance, greater injury risk threshold for the knees (and the back!), and the ability to squat and do work without back discomfort for much longer periods of time.