Maigrir sans y penser

Maintenir notre corps à bonne température est notre première dépense d'énergie, et une des raisons de la hausse de l'obésité aux Etats-Unis est la généralisation de la climatisation. 

Elle permet aux Américains de vivre indépendamment des saisons, de la météo, et des moments de la journée. N'ayant pratiquement plus besoin de s'adapter aux variation du climat, leur métabolisme ralentit, leur consommation de calories baisse... et la graisse s'accumule.

Les désastres de l'air en boîte de conserve

Je participe régulièrement à des congrès qui ont lieu dans des hôtels internationaux : pendant 2 ou 3 jours, nous marinons dans une atmosphère confinée, passant de nos chambres à coucher aux salles de conférence sans mettre le nez dehors.

Les allées et venues se font en ascenseur, les repas se prennent dans le restaurant de l'hôtel. Vous n'arpentez que des moquettes, des salles capitonnées, à la lumière des lampes électriques. Air conditionné oblige, les fenêtres sont verrouillées. La température y est toujours la même. 

L'effet sur l'organisme est spectaculaire : après quelques heures déjà, les paupières deviennent lourdes, la tête cotonneuse, les oreilles bourdonnent. Vos mains sont moites, vos pieds gonflent. Vous êtes assailli de crises de bâillement. Vous cherchez à vous ressaisir en passant à table. Mais après deux repas, l'effet s'inverse. Vous êtes écœuré tout en ayant l'impression de ne pas avoir assez mangé. Vous avez soif en même temps que l'impression d'avoir trop bu. Bientôt, toute votre énergie passe dans une lutte désespérée contre le sommeil ; la voix des orateurs, qui vous berce, les présentations au vidéoprojecteur qui se succèdent, vous imposent des efforts surhumains pour rester éveillé. La nuit, par contre, impossible de fermer l'œil. 

Pour être en forme, le corps a en effet besoin d'être fouetté par les éléments ! Bien loin de vous donner le rhume, rien de tel que la pluie, le vent, la boue, le soleil, le froid, le chaud qui alternent, pour vous fortifier, vous donner la santé.

C'est pourquoi une des premières mesures à prendre si vous souhaitez maigrir, est deréactiver votre
métabolisme en soumettant votre corps à des variations de température, et de conditions atmosphériques.

Baissez le chauffage en hiver, coupez la climatisation l'été

En plus d’économiser de l’énergie, vous augmenterez le métabolisme de votre corps pour se maintenir à la bonne température, et vous perdrez des kilos en trop, si vous en avez.

La douche écossaise

Pour survivre aux congrès, j'ai pris l'habitude de pratiquer la douche écossaise, c'est-à-dire de m'asperger longuement, matin et soir, d'eau la plus froide possible.

Cette pratique peut paraître brutale, mais on s'y fait très bien à partir du moment où on procède par ordre.

On ne commence pas en serrant les fesses et en prenant une douche glacée au sortir du lit.

D'abord, prenez votre douche comme d'habitude, puis vous montez la température, jusqu'à environ 40 °C, c'est-à-dire la température maximale que l'on puisse supporter sans se brûler.

Après quelques minutes à 40°C, vous avez tellement chaud que vous n'avez qu'une envie : baisser la température pour vous soulager. C'est d'ailleurs le principe du bain nordique, qui consiste à alterner séances de sauna et roulades dans la neige.

Vous baissez la température de votre douche, donc, jusqu'à ce que l'eau soit tiède, fraîche, puis vous remontez la température jusqu'à 40 °C. Dès que vous avez de nouveau trop chaud, vous redescendez la température au maximum, et ainsi de suite pendant une quinzaine de minutes, chaque cycle sous l’eau froide durant moitié moins de temps que celui sous l’eau chaude.

A chaque séance, vous verrez que vous supportez de mieux en mieux l'eau froide, jusqu'à découvrir qu'il est en fait très agréable de se passer de l'eau glacée sur le corps.

C’est une pratique qui détend considérablement le corps et qui le fortifie.

Au bout d'un certain temps, vous vous apercevez d'ailleurs que cela ne vous fait plus grand chose, et vous chercherez à retrouver le plaisir de l'eau bien froide en la passant sur les endroits chauds de votre corps : sur la tête, la nuque, les hanches, l'intérieur des cuisses, c'est-à-dire à où le sang se retire lorsqu'on a froid.

Votre corps ré-apprendra ainsi à auto-réguler sa température.

Excellent pour la circulation

• Sous l'eau chaude, artères et veines se dilatent afin de disperser la chaleur plus facilement ;
  
• Sous l'eau froide, elles se contractent pour éviter les pertes de chaleur.
  

Votre système sanguin retrouve sa capacité d'adaptation, augmente son élasticité. Vous luttez contre la rigidification de vos artères.

Après quelque entraînement, les plus robustes passeront directement à l’eau froide au sortir du lit, et vous évitez donc de gaspiller de l'eau et de l'énergie par une douche trop longue et trop chaude. 

Mais quoi qu’il en soit, vous avez tout intérêt à conclure chaque douche en diminuant la température de l’eau. Le fait est là : nous avons tendance à prendre des douches trop chaudes et à être de moins en moins résistants aux fluctuations de températures. D’où une tendance à gagner du poids, et une certaine fragilité en hiver.

A votre santé !

Jean-Marc Dupuis 

Le potage contre l'hypertension

Selon une nouvelle étude publiée par des chercheurs de l'Université de Barcelone, consommer régulièrement du gaspacho réduit de 27 % le risque d'hypertension artérielle. (1)

L'effet bénéfique du gaspacho est dû aux vertus de la tomate, du concombre, de l'ail et de l'huile d'olive, qui entrent dans sa composition et qui tous, individuellement, ont des vertus protectrices pour le cœur et les artères.

L'hypertension se caractérise par une pression anormalement forte du sang sur la paroi des artères. En situation de stress ou durant un effort physique, il est normal que la tension artérielle s’élève. Mais chez les personnes hypertendues, la tension reste élevée en permanence, même au repos ou en l’absence de stress.

A la longue, les artères souffrent, ce qui augmente le risque d'infarctus, d'accident vasculaire cérébral (AVC), d'insuffisance cardiaque (épuisement du cœur), de problèmes aux reins et aux yeux, car les petits vaisseaux sanguins qui les irriguent risquent d'éclater.

Gaspacho délicieux en moins de 15 minutes

Le gaspacho tout prêt Alvalle est vraiment excellent et se vend dans tous les supermarchés, au prix d'environ 3,90 euros le litre. (Je précise que je ne possède pas d'action de la société Alvalle, ni d'ailleurs d'aucune autre société.)

Il contient tomates, poivron, concombre, oignon, huile d'olive vierge extra, vinaigre de vin, sel, ail et jus de citron, et n'a pas de colorant ni conservateur ajouté.

Les légumes étant achetés en gros en Espagne et cuisinés immédiatement par le producteur, vous bénéficiez de l'effet de masse. Il vous sera presque aussi cher de cuisiner votre propre gaspacho, surtout en cette saison où les tomates ont le goût du navet et le prix des cerises.

Toutefois, pour être conservé, ce gaspacho est malheureusement pasteurisé (passé à haute température). Cela détruit en partie sa teneur en vitamines.

Alors voici une recette rapide, facile et bon marché à faire chez vous.

Pour quatre personnes, prenez :

- 6 tomates mures
- 1 concombre
- 1/2 poivron rouge
- 1/2 poivron vert
- 2 petits oignons
- 1 gousse d'ail
- 2 jus de citrons (ou plus, selon les goûts)
- 6 cuillères à soupe de vinaigre
- 1/2 verre d'huile d'olive
- basilic
- piment en poudre
- poivre et sel
- un verre d'eau

Préparation de la recette :
Réduisez l'ail et l'oignon en purée.

Lavez tous les autres légumes, épluchez le concombre, épépinez les poivrons, puis coupez les en morceaux.

Mixez les légumes avec la purée d'ail et d'oignon, puis ajoutez l'huile, le vinaigre, le jus de citron, le basilic, le sel, le poivre et le piment. Si la mixture reste trop épaisse, ajoutez de l'eau.

Bien mélanger et mettre au frigo deux heures.

Une recette idéale à faire avec les enfants : comme vous le voyez, il est a peu près impossible de rater un gaspacho...

Un peu de vocabulaire

Vous avez peut-être noté que j'ai intitulé cette lettre « Le potage contre l'hypertension », et non la soupe contre l'hypertension.

Le potage est une préparation de légumes et éventuellement de viande bouillis dans de l'eau, et qu'on mange avec l'eau de cuisson, mixée ou non.

Si vous décidez de sortir tous les morceaux et de ne garder que le jus, ce n'est plus du potage, mais du bouillon.

Votre potage ou votre bouillon deviennent une soupe lorsque vous les versez sur une tranche de pain. C'est le plat traditionnel des paysans français, qui n'est quasiment plus consommé aujourd'hui. Au Moyen-Âge, le mot soupe ne signifiait d'ailleurs pas la préparation liquide, mais la grosse tranche de pain elle-même, qui servait d'assiette et sur laquelle on versait la nourriture.

Les gastronomes dégraissent, filtrent leur bouillon, puis dégustent chaud ou glacé le précieux liquide ainsi obtenu : on parle alors d'un consommé, et il est souvent garni de morilles, d'asperges, de truffes ou aromatisé avec des vins madérisés.

Si, juste avant de le servir, vous liez votre potage avec de la crème fraîche, et que vous moulinez le tout pour obtenir une texture parfaitement onctueuse, il s'agit alors d'une crème. 

Ajoutez à cette crème un jaune d'œufs, pour mieux la lier que la crème fraîche, et vous dégusterez un velouté.

Il existe enfin une sorte particulière de velouté : lorsque l'ingrédient principal est un crustacé, on parle d'une bisque.

Avec ça, vous ne risquez plus de confondre potage Dubarry, crème Dubarry et velouté Dubarry...

A votre santé !

Jean-Marc Dupuis 

Fasting may protect against disease; some say it may even be good for the brain

By Emma Young -- New Scientist, Published: December 31

In 1908, Linda Hazzard, an American with some training as a nurse, published “Fasting for the Cure of Disease,” which claimed that minimal food was the route to recovery from a variety of illnesses, including cancer. Hazzard was jailed after one of her patients died of starvation. But what if she was, at least partly, right?

A new surge of interest in fasting suggests that it might indeed help people with cancer. It might also reduce the risk of developing cancer, guard against diabetes and heart disease, help control asthma and even stave off Parkinson’s disease and dementia.

“We know from animal models,” says Mark Mattson at the National Institute on Aging, “that if we start an intermittent fasting diet at what would be the equivalent of middle age in people, we can delay the onset of Alzheimer’s and Parkinson’s.”

Until recently, most studies linking diet with health and longevity focused on calorie restriction. They have had some impressive results, with the life span of various lab animals lengthened by up to 50 percent after their caloric intake was cut in half. But these effects do not seem to extend to primates. A 23-year study of macaques found that although calorie restriction delayed the onset of age-related diseases, it had no impact on life span. So other factors, such as genetics, may be more important for human longevity.

That’s bad news for anyone who has gone hungry for decades in the hope of living longer, but the finding has not deterred researchers who study fasting. They point out that although fasting obviously involves cutting calories — at least on specific days — it brings about biochemical and physiological changes that daily dieting does not. Besides, calorie restriction may leave people susceptible to infections and biological stress, whereas fasting, done properly, should not.

Some even argue that we are evolutionarily adapted to going without food intermittently. “The evidence is pretty strong that our ancestors did not eat three meals a day plus snacks,” Mattson says. “Our genes are geared to being able to cope with periods of no food.”

Trying out a fast

Fasting will leave you feeling crummy in the short term because it takes time for your body to break psychological and biological habits, researchers say. There isn’t really agreement, though, on what fasting entails. To research this article, I am trying out the “5:2” diet, which allows me 600 calories in a single meal on each of two weekly “fast” days. (The normal recommended daily intake is about 2,000 calories for a woman and 2,500 for a man.) Proving that fasting is not necessarily about losing weight, I am allowed to eat whatever I want on the five non-fast days.

A more draconian regimen than the 5:2 plan has restricted-calorie fasts every other day. Then there’s total fasting, in which participants go without food for one to five days. (Fasting for more than about a week is considered dangerous.) This might be a one-off experience, or repeated weekly or monthly.

Different regimens have different effects on the body. A fast is considered to start about 10 to 12 hours after a meal, when you have used up all the available glucose in your blood and start converting glycogen stored in liver and muscle cells into glucose to use for energy. If the fast continues, there is a gradual move toward breaking down stored body fat, and the liver produces “ketone bodies,” short molecules that are byproducts of the breakdown of fatty acids. These can be used by the brain as fuel. This process is in full swing three to four days into a fast.

Various hormones are also affected. For example, production of insulin-like growth factor 1 (IGF-1) drops early and reaches very low levels by Day 3 or 4. It is similar in structure to insulin, which also becomes scarcer with fasting, and high levels of both have been linked to cancer.

As for treating cancer, Valter Longo, director of the Longevity Institute at the University of Southern California, thinks that short-term complete fasts maximize the benefits. He has found that a 48-hour total fast slowed the growth of five of eight types of cancer in mice, the effect tending to be more pronounced the more fasts the animals undertook.

Fasting is harder on cancer cells than on normal cells, he says. That’s because the mutations that cause cancer lead to rapid growth under the physiological conditions in which they arose, but they can be at a disadvantage when conditions changes. This could also explain why fasting combined with conventional cancer treatment provides a double whammy. Mice with gliomas — very aggressive forms of cancer and the most commonly diagnosed brain tumor in people — were more thantwice as likely to survive a 28-day study if they underwent a 48-hour fast accompanied by radiation therapy as were those that did not fast.

Could fasting prevent cancers from developing in the first place? Evidence is scant.

Longo says there are “very good reasons” why it should. He points out that high levels of IGF-1 and glucose in the blood and being overweight are risk factors for cancer, and they can all be improved by fasting.

Another risk factor is insulin, says Michelle Harvie at Britain’s University of Manchester. Studying a group of women whose family history put them at high risk of developing breast cancer, she put half of them on a diet that cut calories by about 25 percent and half on a 5:2 fast. After six months, both groups showed a reduction in blood insulin levels, but the reduction was greater in the fasting group. Harvie’s team is now analyzing breast biopsies to see whether this translates to fewer of the genetic changes associated with increased cancer risk.

The effect on diabetes

High insulin is also associated with Type 2 diabetes, so perhaps it is no surprise that fasting shows promise there, too. At the Intermountain Heart Institute in Murray, Utah, Benjamin Horne has found that a 24-hour water-only fast, performed monthly, raises levels of human growth hormone. That hormone triggers the breakdown of fat for energy use, reducing insulin levels and other metabolic markers of glucose metabolism. As a result, people lost weight, and their risk of getting diabetes and coronary heart disease was reduced. Alternate-day fasting (with a 500-calorie lunch for women and a 600-calorie meal for men on fast days) has similar benefits, says Krista Varady of the University of Illinois. She has seen improvements in people’s levels of low-density lipoprotein cholesterol, or “bad cholesterol,” and blood pressure in volunteers eating either a low-fat or high-fat diet on “feeding” days.

For people who are overweight, any kind of intermittent fasting diet will probably help reduce the risk of diabetes and cardiovascular problems, Mattson says. In 2007, he found another benefit, too. He put 10 overweight people with asthma on an alternate-day incomplete fast and found that their asthma symptoms improved after just a few weeks. Blood markers of inflammation, including C-reactive protein, also decreased, suggesting that the fast was helping to moderate their overactive immune system.

Whether fasting would benefit normal-weight people with asthma or other conditions associated with an overactive immune response remains to be seen. There is some evidence that alternate-day fasting can lower their levels of blood fat. However, Mattson suspects that with diabetes and cardiovascular disease, fasting may not be as beneficial for people of normal weight as it is for people who are overweight, simply because they are already likely to be in pretty good shape, metabolically speaking.

How the brain reacts

Mattson has, however, identified another effect of fasting that he believes can benefit everyone: It is good for the brain. “If you look at an animal that’s gone without food for an entire day, it becomes more active,” he says. “Fasting is a mild stressor that motivates the animal to increase activity in the brain.” From an evolutionary perspective, this makes sense, because if you are deprived of food, your brain needs to work harder to help you find something to eat.

His studies suggest that alternate-day fasting, with a single meal of about 600 calories on the fast day, can boost the production of a protein called brain-derived neurotrophic factor by 50 to 400 percent, depending on the brain region. This protein is involved in the generation of new brain cells and plays a role in learning and memory. It can also protect brain cells from the changes associated with Alzheimer’s and Parkinson’s. In mice engineered to develop Alzheimer’s-like symptoms, alternate-day fasting begun in middle age delayed the onset of memory problems by about six months. “This is a large effect,” Mattson says, perhaps equivalent to 20 years in humans.

So, what about the common advice to start the day with a good breakfast? Mattson believes it is flawed, pointing out that the studies supporting this idea were based on schoolchildren who usually ate breakfast; a decline in their academic performance might simply be due to the ill effects that occur when people begin fasting.

Mattson skips breakfast and lunch five days a week, then has dinner and normal weekend meals with his family. Varady has tried alternate-day fasting, but she likes to eat dinner with her 18-month-old child and husband, so she does all her eating within an eight-hour period each day.

Harvie sounds a cautious note for anyone thinking of giving fasting a go. “We still don’t know exactly who should be fasting, how often or how many days a week,” she says. Also, it may not be without risks. One study in rats, for example, found that an alternate-day fast for six months reduced the heart’s ability to pump blood.

There is also the fact that fasting is difficult. Varady finds that 10 to 20 percent of people who enroll in her studies drop out, unable to stick to the regime. This may be less of a problem in the future, though. Some researchers are investigating the possibility that you can get some of the health benefits of fasting simply by reducing protein intake.

As I count down the minutes to the end of my fast, I can’t help but wish them success.

This story was produced by New Scientist magazine and can be read in full at www.newscientist.com.

Le fer peut tuer

Le manque de fer est une des carences les plus répandues au monde. 25 % environ des êtres humains sont touchés, selon l'Organisation Mondiale de la Santé !

Manquer de fer est très gênant, parce que le fer est indispensable pour vous oxygéner. Lorsque vous respirez, l'oxygène qui arrive dans vos poumons passe dans votre sang. Plus exactement, il passe dans les globules rouges qui sont dans votre sang et, plus exactement encore, dans une protéine qui est à l'intérieur de vos globules rouges, l'hémoglobine.

Or, au cœur le plus secret de l'hémoglobine, se trouve un atome de fer, et c'est à cet atome que se fixe l'oxygène.

Si vous manquez de fer, vous ne pouvez produire assez d'hémoglobine. Vos globules rouges s’aplatissent, votre teint devient jaunâtre, vous vous sentez faible et le moindre effort vous essouffle. Maux de crâne et vertiges vous accablent. Tout cela parce que votre sang ne transporte plus assez d'oxygène pour approvisionner correctement vos muscles et votre cerveau.

La fatigue est d'autant plus forte quand vous manquez de fer qu'il est essentiel à la production de l'adénosine triphosphate (ATP), source première de l'énergie corporelle, dans vos cellules. Il permet à vos muscles de stocker de l'oxygène dans la myoglobine. Enfin, il régule la croissance et la différenciation des cellules.

Il est donc important de ne pas manquer de fer.

Qui risque de manquer de fer ?

Près de 99 % de toutes les cellules sanguines sont des globules rouges. Vous devez continuellement produire des globules rouges pour remplacer ceux qui meurent, ainsi que l'hémoglobine qui les remplit.
Les enfants, qui grandissent, et qui ont donc besoin en permanence d'accroître leur volume total de sang, peuvent manquer de fer.

Les femmes qui ont leurs cycles menstruels, et qui perdent donc régulièrement du sang,  peuvent aussi manquer de fer. On estime que c'est le cas de 20 % d'entre elles. 

Mais les personnes les plus à risque de manquer de fer sont les femmes enceintes, qui puisent dans leurs réserves pour constituer celles de leurs enfant. 50 % des femmes enceintes manquent de fer, au point que les médecins leur prescrivent presque automatiquement des compléments de fer.

En revanche, les hommes adultes qui ne se blessent pas, ni ne saignent du nez, mais qui mangent beaucoup de viande rouge, ou d'autres aliments riches en fer (voir ci-dessous), risquent fort de souffrir d'un excès de fer dans leur organisme, ce qui est dangereux :

Votre corps peine à éliminer les excès de fer

Notre corps est capable d'éliminer la plupart des nutriments en excès que nous absorbons. Une personne qui consomme trop de vitamine C ou de calcium, par exemple, va éliminer les excès par les urines. Les médecins parlent de mécanisme « d'excrétion », qui veut dire élimination. L'excrétion se fait principalement par les urines, par la bile (dans les intestins), et par la sueur.

Mais ce n'est pas le cas pour le fer.

Il n'existe que deux moyens d'excrétion du fer : par l'élimination de cellules mortes de la peau ou des voies digestives ; ou par les pertes de sang.

Ces deux mécanismes sont très lents, surtout pour les hommes qui ne perdent pas de sang. Le fer risque alors de s'accumuler dans l'organisme.

Le problème est que le fer rouille. Il « s'oxyde » dit-on. Si vous avez trop de fer dans le corps, cela produit une oxydation massive de vos tissus. Les cellules du pancréas sont particulièrement vulnérables au fer. Ce sont elles qui fabriquent l'insuline, une hormone qui régule le taux de sucre sanguin. Trop de fer peut détruire les cellules du pancréas et provoquer un diabète de type 1 (provoqué par l'incapacité du pancréas à produire de l'insuline), une maladie dangereuse, qui peut rendre aveugle et qui est la principale cause d'amputation actuellement.

En abîmant les cellules qui tapissent vos artères, l'excès de fer peut aussi provoquer desmaladies cardiovasculaires, qui peuvent elles aussi être graves voire mortelles : infarctus, accident vasculaire cérébral (ce qu'on appelle une « attaque » ou AVC), insuffisance cardiaque (fatigue du cœur).

Enfin, parce que l'oxydation abîme les cellules et en particulier l'ADN, elle peut provoquer l'apparition de cellules cancéreuses qui, se multipliant, provoquent des tumeurs.

Vous le voyez, l'excès de fer est un problème à prendre très au sérieux.

Êtes-vous concerné ?

Pour savoir si vous êtes concerné, il ne suffit pas de mesurer votre taux de fer sanguin. La mesure la plus utile pour connaître votre statut en fer est de mesurer la quantité de ferritine présente dans votre sérum (le liquide jaunâtre dans lequel baignent les globules rouges). Cette analyse doit toujours être effectuée à jeun, car la plupart des gens sont en excès de ferritine après avoir mangé.

Le niveau optimal de ferritine sérique (dans votre sérum) est de 40 à 60 ng/mL. Une petite marge est permise, mais en-dessous de 20, vous êtes en déficit et au-dessus de 80, vous êtes en excédent.

Les niveaux de ferritine peuvent monter extrêmement haut. Il arrive qu'ils dépassent 500, voire 1000 ng/mL. A ce niveau, le dommage oxydatif est très intense.

La solution

La solution est simple. Si vous avez trop de fer, il suffit de participer au don du sang.

En faisant deux ou trois dons par an, vous pourrez maintenir votre taux de ferritine à un niveau sain.

Si vous manquez de fer

Pour les personnes qui ont le problème inverse, et qui manquent de fer, la première solution n'est pas de prendre des compléments alimentaires, mais de manger des aliments riches en fer, ainsi que de la vitamine C car elle en augmente l'absorption.

L'aliment riche en fer assimilable le plus courant est la viande rouge. Choisissez une viande de haute qualité, de bovins nourris à l'herbe, si possible issus de la filière biologique.

Mais l'aliment le plus riche en fer est la palourde : fraîches et bouillies, ou même en conserves, une portion de 80 g de palourdes (6 palourdes environ) vous apporte 18 mg de fer, soit l'apport quotidien recommandé pour une femme de 19 à 50 ans. Pour les femmes enceintes, la dose recommandée est de 27 mg/j. Pour les hommes, ainsi que pour les femmes ménopausées, 8 mg/j.

Les foies de bœuf et de volaille sont également riches en fer (6 mg pour 100 g). Certaines sources végétales sont également intéressantes (tofou, haricots blancs, lentilles, épinards), mais il faut savoir qu'il s'agit alors de fer « non-héminique », que nous n'absorbons qu'à 5 %, contre 25 % pour le fer héminique que l'on trouve dans la viande, le poisson et les crustacés.

Attention aux compléments de fer

Essayez autant que faire ce peut de corriger vos déficits en fer par l'alimentation. Si ça ne suffit pas, le recours à des compléments de fer peut être nécessaire, mais la plus grande vigilance s'impose alors.

Tout d'abord, de nombreux effets indésirables sont à craindre. Le mieux connu est la constipation, mais une supplémentation en fer peut également provoquer des nausées et vomissements. Il est donc conseillé de commencer par une très faible dose puis augmenter petit à petit. Prendre le complément le soir avant d'aller se coucher peut aussi diminuer les inconvénients ressentis.

D'autres part, toutes les formes de fer que vous trouvez dans les compléments ne se valent pas :

Le sulfate ferreux, que vous retrouvez dans le Tardyféron, le Timoferol et le Piedaven ainsi que dans de nombreux multivitamines, y compris pour les enfants, est une forme relativement toxique et non-organique de fer, qui peut causer de graves problèmes, allant jusqu'au décès en cas d'overdose. Et le simple fait pour un enfant d'avaler d'un coup un tube de multivitamines enrichies en fer peut déjà provoquer cette overdose, des cas ont lieu chaque année.

Il existe des formes organiques de fer, produites à partir du pentacarbonyle de fer, qui sont plus assimilables par l'organisme, par exemple le biglycinate ferreux, qui se compose d’une molécule de fer ferreux liée à deux molécules de glycine.

Toutes les bonnes préparations orales de fer donneront une couleur noirâtre aux selles. Cela est normal et ne signifie pas qu'il y a une perte de sang. 

Attention, ne prenez PAS de compléments alimentaires de fer, y compris les formes organiques si vous souffrez :

• d'hémosidérose, et en particulier d'hémachromatose ;
  
• d'anémie hémolytique.
  

Enfin, même si vous prenez du pentacarbonyle de fer, qui n'a pas la dangerosité du sulfate ferreux, veillez tout de même à ne pas le laisser à portée des enfants.

Aidez vos proches

Peu de médecins alertent leurs patients sur les risques d'excès de fer dans l'organisme, et la plupart oublient de prescrire régulièrement des analyses du taux de ferritine sérique.

Vous pouvez facilement partager cet article avec vos amis en le leur transmettant. Le niveau de fer peut avoir un impact majeur sur la santé et, qu'il soit trop haut ou trop bas, vous pourrez aider un nombre considérable d'amis à aller mieux par la simple recommandation de se faire analyser leur taux de ferritine sérique, ce qui est simple et bon marché.

A votre santé, et bonne année !

Jean-Marc Dupuis 

****************************** 

Stretching Doesn't Work

by Dean Somerset – 12/28/2012
I spend most of my day working with sedentary office workers who toil in cubicle mines for an average of 8-12 hours a day. Not surprisingly, most arrive at my door with the mobility of a clam, which makes training them to do even simple things like hip hinges, squats, and other staples of a training program a challenging endeavor.
However, static stretching alone is not the answer. In fact, it barely provides any benefit at all.
No matter how much time a client spends stretching, they typically see only transient improvements in flexibility and negligible improvement in motor control when performing any movement using that new range of motion.
As a result, I've dropped almost all static stretching from my programs in favor of some more advanced mobility methods I'll discuss here.

Banana Hammock Splits

Let's start with the basics. "Mobility" means increasing the usable range of motion at a joint or joints in the hope that this increased range of motion allows for performance benefits and injury prevention.
This new range of motion should stick, or at least be something you can get back relatively quickly, as the only limiting factor should be the joint structure itself.
Everyone should theoretically be able to do the splits. The hip joint can get to 170 degrees of flexion, and in some angles outside of the saggital plane it can get to more than 200 degrees flexion. It can also extend to between 40-60 degrees, which adds up to way more than the necessary 180 degrees to do a split.
This leaves soft tissue restrictions as the reason most people can't tea bag the floor. Sure, some have structural issues with the shape of their hip joints, but that can't be something that could account for the entire population.
Flex Wheeler used to hit the splits on stage, carb depleted and dehydrated while packing more muscle than 95% of the population, proving the concept of being "muscle bound" to be complete and utter horse shit.

Why "Stretching" Won't Make you Stretchy

The common thought process regarding static stretching is to hold an elongated position for 20-30 seconds to create additional length within a muscle to allow for a greater range of motion.
This is good in theory, but in practice it doesn't seem to happen. If stretching is supposed to increase range of motion, why do people keep stretching while remaining chronically "tight"?
A better question would be why is that muscle or tissues so tight that they require stretching in the first place? Muscles are stupid creatures and they only do what they're told to do. The nervous system calls the shots and if it says contract, the muscle contracts.
If the brain tells a muscle "get tight," it's for a reason, usually to produce movement (eccentric or concentric action), provide stability, or to protect joints during novel movements or ranges of motion.
The muscles of the hips are getting tight to try to provide some level of stability for another area of the body that doesn't have it, so you can move efficiently and without pain.
This means that simply stretching a muscle without figuring out why it's tight will just result in it getting tight again.
Below is a video to show the thought process in action with a live assessment and corrective strategy. Watch what happens with her left hip internal rotation:

She didn't have to move her hip through any kind of range of motion to gain that new mobility, so we know stretching wasn't going to be the answer.
Some people claim that static stretching helps increase the length of the muscle, which is almost as possible as me caring about Kim Kardashian or not being glued to the TV when the movie, Blood Sport,is playing.
If you grab a rope and pull it, it gets longer for as long as the tension is applied, but then when you let it go it returns to its normal length. That is unless you start ripping fibers and causing some irreparable damage.
Gymnasts and dancers have crazy mobility for life because they tend to go through deformational changes as children to help them get deeper stretches and more range of motion through alterations to their femoral head and neck, hip capsule, and almost every other joint where freaky mobility is necessary for their sport.
Static stretching a muscle is the same. Sure, it changes length for a little while, but returns quickly. There's no way stretching will add sarcomeres in series – which would actually increase the length of the muscle – without long sustained holds of about 20-30 minutes, as shown by some studies.
Additionally, static stretching reduces your ability to produce muscular force, meaning you're less likely to push massive weights and catch the attention of someone who may want to see you naked. Who would want to limit themselves like that?

What Else Could You Do?

While many people think foam rolling is a method of stretching, it's not. The length of the muscle or tissue isn't undergoing any kind of length change, but rather a neural down-regulation that reduces resting tone in prime movers, meaning you can move more easily and with a better chance of having balanced tension around the joint.
It's a testament to how resetting the neural tone of a tissue can help increase range of motion faster than simply stretching.
But again, un-gluing a chronically tight area without restoring stability to the tissues it's trying to help stabilize will only result in it getting tight again.
Chronic IT band pain? Look at how your hips and feet are moving, how your knees are positioned during your squats, and also your lateral core stability on that side.
Start off by gripping the floor and trying to form an arch in your foot whenever you have it in contact with the ground. You should be thinking of using your heel and the ball of your foot to shorten your sock without curling your toes.
From there, drive the knees out when squatting and deadlifting, so you keep the knees vertical over the feet instead of letting it cave in a valgus stress.
Foam rolling should be the first step to regaining lost mobility, specifically for the hips, typically occupying the first 5 minutes or so of any training session. Go super slow through all the tight spots, slow enough to make glaciers say, "Slow down!"
Traction is another form of mobility that can be applied to anyone and is a very effective form of mobilization to help un-glue sticky joints. I picked up a version of a dynamic traction movement with a thick elastic band from Kelly Starrett.
This involves having the band up high on the thigh, close to the hip joint, and rocking side to side. The elastic is pulling the hip joint slightly apart, while the action of the rocking helps to get the muscles working around the hip while in the new joint position.

(Just watch out so you don't get your junk caught in the action.)
This can help reduce the resting tension of the muscles around the joint as it reduces the compressive signaling in the muscles supporting the joint.
An additional benefit is that the mild compression on the adductor muscles of the inner thigh can help increase activation and provide a better chance of total joint stability rather than simply addressing hamstrings and glutes.
The adductor magnus also causes a degree of hip extension, so spend some time on that as well when you're trying to build your posterior chain.
Traction has commonly been used in therapeutic settings to provide a decreased stimulus to overactive muscles and receptors, and encourages an increase of fluid delivery into the joint spaces. Decompression tables for disc injuries are a common method of traction.
In passive settings it's effective, but again doesn't address the muscular stabilization component mentioned earlier. Having the dynamic rocking as shown here helps clean this up nicely.
Active mobility comes into play with the newly unlocked joints and tissues. The role of active mobility is to train the body to use the range of motion in the most effective way possible so that the likelihood of maintaining this new range is higher than simply rolling in to the gym at peak hour, squatting heavy, high fiving everyone in the gym and then going home.
The major directions that tend to be lacking in hip mobility are full hip flexion (bringing the knee to the chest), abduction (legs wide apart), external rotation (crossing an ankle over your knee), and even hip extension.
When doing any active mobility, it's best to try to get all the movements down as fast as possible while focusing on getting the movement to come from the hip and not from the lumbar spine.
Focus on keeping the spine tense and the core active while sinking deep into the stretches, hold each for a single breath per rep, and continue on to the next one.

Putting it all Together

So to outline a plan of attack to get your hips going in the right direction:

1. Foam rolling: Super slow, hips, IT band and adductors – 5-10 minutes
2. Traction: Super slow and concentrated – 2 sets x 15 reps
3. Active Mobility: Core tense and focus on breathing – 2 x 8-12 reps each side

The total time needed to get the hips singing a happy tune should only be about 15 minutes. If this 15 minutes means the difference between squatting deep into the hole and developing a bigger and better squat, or getting your hips back in a deadlift without having your low back flex to compensate, you'll have a greater chance of pulling big numbers and not getting injured.
I should also say that having more hip mobility opens up more possibilities for exercises you can do, which will help reduce boredom and monotony in the gym. It can also increase the number of, ahem, positions you can get into outside of the gym.
You're welcome.

References

Winchester et al (2009). A single 30-s stretch is sufficient to inhibit maximal voluntary strength. Research Quarterly for Exercise and Sport. Vol 80 (2) pp. 257-261.

Liebenson C: Rehabilitation of the Spine Ð A Practitioners Manual. 2^nd edition Williams and Wilkins. 2006.

6 Interesting Things About Strength

by Tim Henriques – 12/26/2012
Strength is a seductive temptress and I have no shame in proclaiming my love for her. But like anything in life that gets your juices flowing, to truly understand strength you must consider both the stuff you like and the stuff you don't like.
Here are 6 very interesting things about strength.

1. The Best Thing About Strength

The best thing about strength – in my opinion of course – is that anyone can improve from their starting level of strength. I'm not suggesting that everyone is capable of becoming a world record holder, but everyone can get better.
You might start out struggling to bench the bar and then a year later be using 150 pounds – not fantastic but still a lot better than where you started.
Being strong is an inherently relative concept. The good news (which I say with tongue planted firmly in cheek) is that as the general fitness level of the average person declines, it actually becomes easier to set oneself apart and become that much stronger than average.
Train several hours a week or more, train hard, incorporate the main lifts, follow progressive overload, stick with it for an extended period of time (measured in years, not months), and you'll get significantly stronger than when you started, not to mention a hell of a lot stronger than a "normal" person. In addition, as the strength comes, so do all the health benefits that accompany it.

2. The Worst Thing About Strength

The worst thing about strength – in my opinion – is that strength is specific, not general. Most people think strength is a single, all-encompassing quality, i.e., a person is strong or not.
An example of this line of thinking would be the comic book character The Hulk. The Hulk is super strong, which means he can do anything that's related to strength – pick up cars, throw tanks, cause earthquakes by smashing the ground, even fly because he can jump super high. Hell, his muscles are so strong that bullets simply bounce off him.
Unfortunately it doesn't work that way, as there's no single "strength quality." If there were, then the world champion arm wrestler, powerlifter, weight lifter, shot putter, and the World's Strongest Man would all be the same person. But it's not, nor has ever been the same person. Fact is, nobody's ever been on top in even two of those categories, except for the immortal Bill Kazmaier.
The reason for this all relates to the principle of specificity. Muscles don't function independently of the nervous system, and for every movement we need a motor pattern. In order to operate at very high levels, this motor pattern must be trained regularly. If it isn't, an individual may not be able to use the strength they've developed in one context in another, unrelated one.
In the classic Supertraining, Siff states that strength should not be viewed as "the ability to produce force by the action of the muscles," but instead that "strength is highly context dependent" and "can manifest itself into many forms."
To be clear, I'm not saying that there's never a relationship between strength in one activity and strength in another; what I am saying is that it's more of a tenuous relationship than one might assume.
If two activities are very similar – for example, deadlifting and picking up the back end of truck – there's likely considerable transfer, but bench pressing and punching through bricks might not be as related.
Strength is specific and not general, and therefore we can't simply rank people on something as broad as "strength" and accurately predict how they'll perform in all settings.

3. The Best Thing About Strength that Gets the Least Attention

Strength is easy to measure if you accept the common standards of testing it, such as seeing how much weight can be lifted with a barbell. This is an invaluable though often overlooked attribute – because strength can be easily measured, every set and rep gives the lifter precise, instant feedback.
Consistent practice with a focus on self-improvement is the key to mastery of any skill. Strength training brings that idea home like nothing else.
Imagine if an expert sat behind you as you typed up a paper, and after every paragraph gave you feedback about what was good and what was bad. Initially it might drive you crazy, but because she had expertise in the subject, the feedback would ultimately make you more confident in what you were writing about.
Nowhere else in life do we get such constant, clear feedback as at the gym, and this goes a long way towards building confidence and boosting self esteem. It's very empowering to see yourself succeed at something challenging as a result of your hard work, and I believe that all those positives can be traced back to the fact that strength is easy to measure.

4. The Thing You Might Not Have Known About Strength

For a single, all-out effort, assuming accuracy and injury are taken into consideration, it's likely impossible to be too strong. However, for other activities, particularly where endurance is a component, one can be too strong for the activity.
A few years ago I was helping my brother move. He'd boxed up everything and packed it into a U-haul truck and drove to his new place, and then I unloaded everything for him.
Let's assume we both did the same amount of work (i.e., we each moved the same number of boxes and the boxes weighed the same). My brother is moderately fit but not strong, certainly not by powerlifter standards – I would estimate he could deadlift 350 as his 1RM. To keep it simple, let's say that I'm twice as strong as he is, at least in the deadlift.
So there I am, unloading the truck and moving 120 boxes into the house and I started getting tired. More specifically, it was my erectors that were getting tired. How could this be possible if I was twice as strong as him? How could he do the same amount of work without much problem?
Each muscle has a certain number of motor units (a motor nerve and their accompanying muscle fibers) in it. Each motor unit can generate some level of force. Let's say for simplicity's sake that we both had 100 motor units in our erectors. Keep in mind that one benefit of training is the trainee learns how to better contract, or turn on, the tougher-to-fire motor units (type IIB), which generate the most strength. Also remember that the boxes didn't have weights labeled on them, and when moving objects of unknown weight one typically over-contracts to make sure their muscle force overcomes the resistance.
When my brother was loading up the boxes he may have contracted half or fewer of his motor units, and he was likely hitting mainly the slow twitch ones with just a few fast twitch thrown in. These motor units don't generate much fatigue and these boxes weren't super heavy – most were likely less than 50 pounds – so a huge level of strength wasn't required to lift them.
I theorized that I'd be more likely to stimulate the bigger type II motor units, which generate more force but also produce more waste products when they contract. Each individual box likely felt a bit easier to me but rep after rep, my erectors were over-contracting, using too much force per motor unit to get the job done, which ultimately led to the feeling of fatigue.
It's worth noting that training doesn't increase the total number of motor units you have; instead it increases how much force each one can produce and how many motor units you can use.
To summarize, my brother might have been contracting 50 of his motor units, each one generating 2 pounds of force, and thus his total level of fatigue wasn't great. I might have been contracting 65 motor units, each one generating 4 pounds of force, and thus I was working too hard for the task at hand.
So in essence, I believe one can be too strong for certain tasks, especially in relatively low resistance, endurance type activities.

5. The Thing You Kind of Know About Strength

Joint health is extremely important to strength. The body has sensors and proprioceptors throughout its framework to tell it what's going on. Joint stability and joint integrity is a very important concept for the body. If your joint is in pain, the body will turn off (deactivate) parts of the agonist muscles that cross the joint and produce the movement.
The body does this because the lower levels of force represent a reduced chance of injury to the already fragile joint. This is why, in my opinion, it's generally not advisable to train through joint pain. Even if you're tough enough to do it, you're using less of your muscle so you'll get compromised results – this is ignoring the fact that the pain is a warning something is wrong and further work might really mess up the joint.
While many factors affect joint health, a big one is joint stability. This is a reason why lifting aids like a belt or a bench shirt have become popular – the belt adds to the stability of the joint by externally stabilizing it. This allows the muscles that cross the joint to contract more strongly (recruiting more motor units) and thus more weight is lifted or more force generated.
This is also why powerlifters who wear gear (bench shirts, squat suits, etc.) often have a hard time calculating how much their gear helps them. In one sense it's simple – how much can you lift raw versus how much can you lift in gear – but another factor is how much the gear is adding to the stability of the joint and thus allowing the muscles to contract more forcefully.

6. The Thing You Always Read About Strength But Never Take to Heart

Bodyweight has a huge impact on strength. Some exercises are more affected by bodyweight than others, such as the bench press, military press, and squat. It's not just how much actual muscle or lean mass you have, but simply total bodyweight.
This ties in closely with the point made above. One of the ways to boost joint stability (and thus increase the muscles ability to contract) is to gain weight.
As you gain weight (10 pounds is usually enough to notice a bit of a difference) your surrounding tissues (even if it's extra fat) will buffer and support the joint, similar in the way that an external wrap would cover and help the joint. This increases stability and in turn increases strength (relative strength may or may not increase, absolute strength almost assuredly will).
I'm not advocating you gain 50 pounds of fat so your bench goes up 10 pounds, but I am suggesting that if you've been at a plateau for quite some time (both with your strength and your bodyweight), you might think about allowing yourself to gain weight to see if that allows your strength to increase noticeably.
That increase in turn, tends to make the training more fun, your enthusiasm is renewed, and you always have the option of losing that weight later on and seeing what happens to you.
Take a look at the line-up from the World's Strongest Man competition. None of them look ready to step onto a bodybuilding stage, but they all look like they're ready to dominate some serious weight, and that extra bodyweight is increasing their joint stability.

It's Time For Strength To Shine

There you are my friends, 6 interesting tidbits about strength. Some may seem more obvious than others but I'd argue they're all important. Which points do you agree with or disagree with? Which one's are new to you? Have you any points of your own?
That's what the Live Spill is for. See you there.

Does Everyone Need To Squat (Deep)?

by Tony Gentilcore – 12/27/2012

This article is about squatting and whether or not everyone needs to (or should) squat deep. To cut the suspense, the answer is no!
Actually, the answer is "it depends."
There's a gulf between the word need and want. They're two very different things.
For example, do you need to crush beers every weekend? No, but you want to. Do you need to bench press three times per week? No, but you want to. Do you need to DVR the Victoria Secret fashion show and watch it every time your girlfriend leaves the room? Yes, yes you do.
As a strength coach, I say people need to squat, and squat well, period. Depth, on the other hand, is more of a "want" issue; I want people to squat deep, but it's just not always feasible. So I work with what I can.
Squats are invaluable for building strength, power, and improving athletic performance.
You'd be hard pressed to find another exercise that helps engage the entire body and, as a result, burn more calories, so even for those more concerned with fat loss or aesthetics, squats are an unparalleled exercise.
Furthermore, squats do a fantastic job of offsetting many of the postural imbalances we see from those who spend much of their lives sitting in front of a computer perusing Facebook or playing Angry Birds on their iPhone.
Someone who can perform a proper squat demonstrates that they have the ample ankle dorsiflexion, hip flexion, hip abduction, t-spine extension, core stiffness, and glenohumeral ROM (among other talents) to do so. This is quite a feat, given many people can't sit down onto a chair without blowing out their back.
So the real question isn't, "Does everyone need to squat?" but rather, "Which squat variation (and by extension, depth) is the safest and most effective for any one individual?"
While I'm 100% in favor of people squatting with a full ROM (which for me is when the front surface of the thighs drop below knee level), sometimes it's just not feasible, and borderline counterproductive.
As an example, encourage someone with chronic anterior knee pain or Femoral Acetabular Impingement (FAI) to squat "ass to grass" and you're setting him or her up for something bad.
Likewise, having someone with a degenerative disc issue do squats could be bad news, as it could for someone who goes into lumbar flexion (butt wink) when going to a certain depth, or someone who has any number of postural imbalances.
Of course, context must always be considered. Every person has a unique injury history and training experience that may or may not dictate what kind of squat variation is indicated.
Too wishy-washy? I don't know about you, but my bullshit meter goes into hyper drive whenever I hear anyone use the words everyone, never, or always.
It's human nature to seek out absolutes, but there really aren't any in the fitness world, or in the "real" world for that matter.
Listen, I'm not saying that I don't do it – I certainly have my biases. I feel everyone should deadlift (in one form or another) at least once a week.
Also, if you have a history of shoulder issues – especially dislocations – you should never perform another dip. Like ever.
Those examples aside, I do a pretty bang up job of not leaning too far to the left or right on any given topic. With few exceptions, I feel there's a time and place for everything – yes, even leg presses (as much as it pains me to admit it), and I'd encourage everyone reading to foster the same approach.
Still, the squat is one hell of an exercise, and I generally lean towards the camp that thinks (most) people should include it – to some capacity – in their programming.

Squat Technique

Of course, much of the time it's simply a matter of placing a premium on coaching someone to squat properly.

• Groove a proper hip-hinge pattern (learn to sit back).
• Coach a more vertical shin angle (especially for those with chronic knee pain), although we can't forget that there's going to be some forward translation of the tibia during any squat.
• Teach clients to push their knees out. I can't even begin to tell you how this simple cue works wonders in helping to clean up squat technique.
• Learn to engage core stiffness (get tight). Each set should begin with taking a big breath and encouraging more apical expansion of the torso. This is something that I've recently started to realize that I've missed the mark on for many years.

Physical therapist Bill Hartman keyed me in on the notion that it's unwise to only focus on pushing the belly out (which encourages more anterior pelvic tilt, and places far more stress on the facet joints of the lumbar spine). Along with pushing the belly out, we also need to be cognizant of attaining lateral and posterior (apical) expansion.

• Learn to engage the lats, and as a result, the thoraco-lumbar fascia to provide more stability to the spine.
• Try not to shit a kidney.

While there's more to it than that, if everyone made it a point to hone in on those key objectives when squatting, we'd undoubtedly see less injuries and (probably) bigger numbers under the bar.
Nevertheless, it can't be understated: it's imperative to teach people to squat within a ROM that's safe for them!
A safe and acceptable depth for one person could be harmful for the next. It's still possible to reap all the benefits of a squat without necessarily going "ass to grass," so it behooves everyone to take the time to find out exactly what their "acceptable" range is.

Assessing Squat Depth

A quick aside: assessment is the foundation for any program that I write. It's a way for me to delve into the bigger picture and construct a program that will allow for the quickest and safest results possible.
More to the point, it's also a way for someone to prove to me that they move well enough that I'm confident they're capable of performing the movements or exercises I deem appropriate for their skill level.
It's important to reiterate that squatting deep is not dangerous or bad. Contrarily, and without getting derailed, squatting deep (whatever that means to you) can be argued to be safer than the alternative, as I noted in this article.
But how do we "assess" the appropriate squat depth for you?
While there are dozens of ways to do so effectively, a great starting point would be a simple drill discussed in the book Deadlift Dynamite, where both Andy Bolton and Pavel quote the godfather of spinal biomechanics, Dr. Stuart McGill:

"In order to find the optimal hip width (or amount of standing hip external rotation), have the athlete adopt a four point kneeling stance. From neutral, rock or drop the buttocks back to the heels.

Mark the angle at which spine flexion first occurs. Then repeat with varying amounts of space between the knees. Look for the optimal knee width that allows the buttocks to get closest to the ankles without any spine motion.

This is the hip angle that will produce the deepest, and ultimately the highest performance squat. It is much wider than most people think. Observe the world champs squatting."

Check out the video below for a demo:

But even this is a somewhat convoluted or limited way to assess things, as squatting by its nature isn't performed in a quadruped position (not to mention squatting is a bit more dynamic in nature, especially under load).
At Cressey Performance, part of our initial assessment with every new client is to take a look at their standing overhead squat and ascertain their squatting proficiency.
If you're curious to play along, here are some simple screens you can perform yourself.

Squat Screen # 1

Assume a shoulder width-apart stance with your toes facing straight ahead and your arms fully extended overhead and then squat down as far as you can go.
What do you notice?
If you're one of the few who can squat all the way down without any major compensation(s) coming to the forefront (heels coming off the ground, knees caving in, excessive lumbar flexion, excessive forward lean, to name a few), congratulations, you get a gold star!
This is more of an evaluative squat assessment, and isn't how I'd go about coaching someone to squat, but more on that shortly.

What this demonstrates is that you have ample hip internal rotation to go into deep hip flexion with very little (if any) ramifications. Granted, we could make a case for hypermobility/laxity, which has it's own set of drawbacks, but the majority of people reading won't have this luxury anyway.
More commonly people will have difficulty attaining proper depth performing this particular assessment, which is why I'll tweak it further.

Squat Screen # 2

Widen your stance, allow for a little "out-toeing," and perform the exact same drill.

Things tend to clean up significantly with this tweak, namely because you're giving yourself a wider base of support and the out-toeing provides a bit more stability, which serves to open up the hips more to attain more depth.
This is how I prefer to coach someone to squat, and deem this more of a performance-based screen.
Plenty of coaches and trainers like to teach squatting with the toes pointing straight head – and more power to them, it's not necessarily wrong – but I argue from a performance standpoint, squatting with a wider base and with some slight out-toeing allows for more weight to be lifted.
That said, if things still look a little dicey, we can move onto the next tweak.

Squat Screen # 3

Perform the exact same protocol as above, but this time, elevate your heels with a 10-pound plate underneath each foot. Most likely you were able to squat much deeper.
Much in the same way why Olympic lifters wear shoes with a high heel lift, it places the body at a mechanical advantage to squat deep(er).
In the likelihood that using a heel lift drastically improves your depth, it may dictate that you have the ankle mobility of the Tin Man and that you need to address it rather than rely on the heel lift as a crutch.
But let's say that after all those screens you're still having trouble attaining ample depth without compensating in some fashion. What happens then? Are you forever relegated to endless corrective ankle, hip, and t-spine mobility drills, or worse, those cute exercises on a BOSU ball your local pencil-necked personal trainer would have you believe is "functional training?"
Sadly, for many, this is the route they end up taking, and it's all because they don't take the time to dig a little deeper.

Squat Screen #4

Lastly, get rid of the heel lift, grab a 10-pound plate, hold it out in front of you with your arms fully extended, and again squat.

Usually we see a profound improvement not only in squat technique, but also squat depth.
By holding the weight out in front of you as a counterbalance, you're forced to engage your anterior core musculature, which in turn gives the entire body the stability it needs to allow for more squat depth.
Without performing this last screen, many would automatically assume that the reason they can't squat to depth is because of a mobility issue, when in fact, as Alwyn Cosgrove has noted on numerous occasions, it's a stability issue.
Without this differentiation, we can see how many people would be barking up the wrong tree, and doing themselves a massive disservice on the training side of things.
Think what would happen if we omitted or neglected to perform the last squat screen – we'd assume that we have a mobility deficit somewhere and just focus on that one component, rather than address the realissue at hand, namely lack of stability.

So Now What?

Hopefully you understand that using the above screening process can help better determine what would be an appropriate depth for any individual.
And with that information at our disposal, we can also ascertain how to go about addressing some common squatting mishaps.

Like the Tuck Under (Butt Wink)

Some people picked the right parents, have awesome levers, and are able to squat ass-to-grass with no issues at all.

Someone with limited hip flexion that attempts to squat deeper than their anatomy allows inevitably tucks their hips under at the bottom. Invariably this leads to lumbar flexion under a significant load, otherwise known as the butt wink.

Due to any number of reasons, namely atrocious ankle mobility and lack of core stability, the butt "tucks" underneath the pelvis when attempting to go into deep(er) hip flexion.
As a result, it causes a boatload of compressive load on the lumbar spine, and to a lesser degree, which I can't prove with any science, drives Dr. McGill bat shit crazy.
Returning to the quadruped rockback test, lets compare a passable test with a god-awful one.
We saw this one earlier:

As you can see, I'm able to get to a decent depth without any major red flags or noticeable compensation patterns rearing their ugly head. My spine stays relatively "neutral" throughout, and my arms look pretty freakin gunny, thank you very much.
But let's look at what a train wreck looks like:

You should immediately notice a lumbar hinge, and unfortunately, if this were some random person, I'd probably refrain from having them squat past that point of no return.
I mean, if it's this bad with no spinal loading, can you imagine how much of a walking ball of fail this hypothetical person would be if I placed a barbell on his back?

How Can We Fix It?

Fixing a majority of problems with the squat isn't complicated. While everyone is different and I don't like making general recommendations, I've found a few universal themes that generally work wonders for most:

Foam Rolling

It's no one's favorite, it's admittedly not sexy or exciting, and I'm sure many are rolling their eyes as they read this, but just do your foam rolling. Staying on top of tissue quality is important, and foam rolling is one of the easiest ways to do so.

Hammer Ankle Mobility

Specifically hammer ankle dorsiflexion. We need roughly 15-20 degrees of dorsiflexion in order to perform a "clean" squat pattern. Unfortunately, most people live in plantar flexion.
To that end, getting out of any shoe with a heel lift and into one that encourages more of a "minimal" approach – say, the New Balance Minimus – would bode well in your favor.
Likewise, including more ankle mobility drills (knee break ankle mobilizations, wall ankle mobilizations, rocking ankle mobilizations) into your warm-up or as part of a filler to do in between sets of major compound movements would also be wise.

Hammer Anterior Core Strength

If I had to choose one component to serve as the umbrella or main area to spend, this would be it.
As I noted above, lack of core stability/strength is a major monkey wrench in what prevents many people from squatting to a safe depth without something funky happening.
If you're tucking under when you squat it's probably a relative stiffness issue, and it stands to reason that your anterior core is weak or unable to stabilize the pelvis.
There are a number of articles on this site that will provide ample core exercises to choose from, but my favorites in this context would be Pallof presses, various chops and lifts, and plank variations like "stir the pot."

Squat to a Successful Depth

Even if someone elicits faulty squatting patterns, that doesn't mean he or she can't squat.
Instead, squat to a depth that prevents him or her from going into lumbar flexion and allows them some success.
Enter the box squat and squat to box, both superb training tools to teach proper squatting technique and allowing people the luxury of still attaining a killer training effect. Check out the tutorial below.

I know it may give some people a bad taste in their mouth, but if I have to resort to having a client squat to a 16-inch box, so be it. I can always progress them lower, and at the same time not feed into any dysfunction or cause anymore harm.

And I'm Out!

It seems everyone on the Internet can squat 500 pounds ass to the floor without so much as putting a crease in their Under Armor shirt. These same posters, however, are curiously absent when asked to post videos of their awesome "squat so low you leave a wet spot on the floor" technique, especially using superhuman poundages. Pity.
Hey, it's the Internet, where the curtain of anonymity allows chest thumping and bravado to supersede logic and reasoning.
So don't be discouraged. Use the test above to figure out your own personal "best squat depth" while incorporating the drills to help improve it.
And above all else, keep squatting. At least that's something everyone online can agree with!