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The CrossFit stimulus—constantly varied high-intensity functional movement coupled with meat and vegetables, nuts and seeds, some fruit, little starch, and no sugar—prepares you for the demands of a healthy, functional, independent life and provides a hedge against chronic disease and incapacity. This stimulus is elegant in the mathematical sense of being marked by simplicity and efficacy. The proven elements of this broad, general, and inclusive fitness, in terms of both movement and nutrition, are what we term our CrossFit Essentials.

In the first article in his new series on diabetes, Dr. Malcolm Kendrick discusses the long history of diabetes research and introduces several models for understanding the causes of the disease, as well as its progression. While the mechanism underlying Type 1 diabetes is generally agreed upon, debate continues over whether Type 2 is related to fat consumption or raised insulin levels resulting from carbohydrate intake. Kendrick explains and evaluates the arguments for each model.

Read MoreDiabetes, Part 1: Disease Models

The burpee is a versatile movement. In its simplest form, it requires little skill, space, or equipment. However, the framework of the basic movement lends itself to many creative variations, such as burpee box jump-overs, which have the potential for greater intensity and challenge coordination, agility, and balance. 

WatchThe Burpee Box Jump-Over

Several studies support the hypothesis that diet, particularly carbohydrate consumption, affects vision. One study compares the eyesight of hunter-gatherer and industrialized groups and finds myopia skyrockets when indigenous populations adopt a Western diet involving more refined carbohydrates. Another study explores the mechanism behind dietary contribution to myopia and finds increases in insulin promote eyeball elongation in animal models. A third study explores dietary sugar’s links to glaucoma, cataracts, diabetic retinopathy, and macular degeneration. Its authors ultimately recommend avoiding high glycemic index foods.

Read MoreSugar and Sight

Brain insulin resistance is associated with Alzheimer’s disease and cognitive impairment, and the regions of the brain most closely associated with Alzheimer’s pathology are also the regions richest in insulin receptors. The authors of this 2019 review argue these associations may be causal and explore ways hyperglycemia and impaired brain insulin signaling may directly contribute to cognitive decline and Alzheimer’s disease.

Read MoreAlzheimer’s Disease and Diabetes: Insulin Signaling as the Bridge Linking Two Pathologies

"Trainers… apply exercises to their clients in order to induce adaptations in structure and function that lead to improved fitness. In order to do this effectively, reliably and safely, the working trainer must understand the structures they are stressing with exercise to produce the functional change that is fitness. This is the primary reason we learn anatomy and physiology."

Read the article Anatomy and Physiology primer for CrossFit trainers

The muscle-up is a movement that begins from the hang, passes through portions of a pull-up and a dip, then finishes in a supported position with arms extended. Many athletes experience the strict bar muscle up as more challenging than its counterpart on the rings. This is because the pull-up bar creates a fixed object the athlete must navigate around. Pulling the torso high enough and having the patience to delay the transition to the dip is critical to the success of the movement.

Watch The Strict Bar Muscle-Up

In the final installment of his landmark series on the history of heart disease research, Prof. Timothy Noakes summarizes the scientific malfeasance perpetrated by Ancel Keys, the famous progenitor of the diet-heart and lipid hypotheses. Taking on the voice of the prosecution in a hypothetical criminal trial, Noakes levels a series of charges against Keys. These range from scaremongering and manipulating data to withholding important trial results that could have saved millions of lives. Most important, Noakes charges Keys with defying the first rule of medicine — do no harm — and concludes with an indictment of Keys' character: "Keys and his acolytes must be held accountable for the wretchedness their over-promotion of his wrong ideas has wrought on the health of so many people."

Read MoreIt's the Insulin Resistance, Stupid: Part 11

CrossFit trainers are skilled in the art of making many difficult movements accessible for the beginner. A good trainer will guide new athletes through a progression, celebrating the small victories along the way. A great trainer will understand this process is not just for the beginner and continue this system with intermediate and advanced athletes.

WatchHandstand Push-Up Variations

A 2016 review finds preliminary evidence suggesting intermittent fasting and similar eating patterns can reduce markers of cancer risk and progression. More intensive fasts, such as complete fasting on alternating days, show more consistent benefits; more moderate fasts show equivocal clinical impact.

Read MoreCould intermittent energy restriction and intermittent fasting reduce rates of cancer in obese, overweight, and normal-weight subjects?

“Since 1990, Uffe Ravnskov MD PhD has published over 100 scientific papers critical of the cholesterol campaign, proposing new hypotheses and also contending that ‘the successful dissemination of the diet-heart idea is due to authors systematically ignoring or misquoting (contradictory) studies.’”

Read MoreThe Cholesterol Myths: Exposing the Fallacy that Saturated Fat and Cholesterol Cause Heart Disease

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