Author: Matt Laye

Muscle loss and anabolic resistance: lifestyle choices make the difference

You can’t get a prescription for it, and insurance companies don’t recognize it as a disease, but sarcopenia, the gradual loss of muscle during aging, is a condition that many of us will confront at some point in our lives (see prior blog for a general description of sarcopenia, the unusual models that teach us about it, and how caloric restriction protects mice from it). Loss of muscle strength and function puts a person at an increased risk for age-related morbidities and mortality. Yeah, it’s a big deal. While scientists and doctors recognize the dangers of sarcopenia, what happens at the cellular level in humans is still being debated. Simplistically, to maintain muscle mass the amount of muscle breakdown, or “catabolism”, and synthesis, or “anabolism”, must be equal. With sarcopenia, the rate of muscle catabolism exceeds the rate of anabolism. The general consensus among experts is that the rate of muscle protein synthesis decreases during normal aging, while muscle protein breakdown does not change. The rate of muscle protein synthesis is not constant; it increases in response to so-called anabolic stimuli. Anabolic stimuli can take the form of pharmaceuticals, such as testosterone or other steroids, macronutrients, such as dietary protein, and exercise, such as strength training. As we age, our ability to increase muscle protein synthesis in response to anabolic stimuli is reduced, a physiological phenomenon termed “anabolic resistance”....

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When Media and Science Collide

It’s not a surprise that people are confused about the best lifestyle choices to improve and maintain health. Whether the recommendations are for diet or exercise, it seems that every three months there is contradictory advice from the medical community and the people who report on it. Eat eggs…don’t eat eggs. High carb diet…low carb diet. In part, the flood of seemingly contradictory advice is a consequence of the how the media reports on medical research. This seems especially true when medical research contradicts conventional or existing wisdom. Scientific studies on controversial topics are immediately picked up and translated into extravagant claims by the media. These inaccurate and misleading stories gain traction through social media megaphones and are promoted by people that would rather not have to follow the existing medical advice. The advice can justify the unhealthy habits of the non-adherents. An even worse consequence is that these constantly contradictory reports in the media can scare those that had adhered to good behaviors into stopping those behaviors. It was just this past week that several of my friends on Facebook (and in real life) alerted me to the latest sensational and woefully misleading headlines. “Running Too Much May Be as Bad as Sitting Around”, and other similar titles appeared in numerous journals and magazines last week (here, here, here, here). All of these articles report essentially the same thing. You thought running was good for your health, but now...

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SAGE Review: Investigating the Relationship between age and physiological function.

Chronological definitions of aging are easy, yet intuitively we all know that age is not just a number. It’s common to see people who “don’t look their age”, whether it’s a 91-year-old grandmother completing a marathon or a lifelong smoker. These people don’t look their age, and biologically they likely aren’t. How can we explain this? Well, like most of biology, physiological aging is due to a combination of genetics and lifestyle, and is extremely complex. To understand physiological aging, first we need to find a single physiological parameter that predicts chronological aging in a homogenous population. Some studies, such as...

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Staying Strong: Countering the Effects of Sarcopenia

By Matthew Laye Sarcopenia comes from the Greek words sacra, “flesh”, and penia, “poverty”. More specifically, sarcopenia is the gradual loss of muscle mass and strength with age. It’s not a disease, not a condition, and not a syndrome, but rather an unfortunate consequence of the natural aging process. Not to be confused with cachexia (accelerated muscle loss secondary to a disease such as cancer), sarcopenia is slow, progressive, and unnervingly unsuspecting. The 0.5-1% loss of muscle mass each year is deceptive, and unlike many of the consequences of aging, sarcopenia actually starts when we are quite young, generally around the age of 30 (Figure 1). The loss of muscle mass and strength has profound consequences on day-to-day living. Many of these consequences manifest themselves as part of a common definition of clinical frailty, which include weight loss, exhaustion, weakness, slowness, and low levels of activity. Sarcopenia is central to these processes. So what exactly is going on and are there any ways to stop it? Sarcopenia alters muscle structure and function in many different ways.  First and foremost with sarcopenia comes muscle atrophy. Muscle atrophy is the shrinking of individual muscle cells, called muscle fibers (Figure 2). So while you do not lose a substantial number of muscle fibers, the smaller diameter muscle fibers result in reduced strength and mass.  Interestingly, not all muscle undergoes atrophy equally. Muscle fibers can be separated based on size,...

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Buck Institute Begins First Clinical Trial for Treatment of Mild Cognitive Impairment

Two years ago Car Talk, one of the most popular shows on National Public Radio, ended after 35 years on the air. Alzheimer’s disease (AD) was to blame. Co-host Tom Magliozzi had progressive symptoms associated with the disease that affected his sharp wit and jovial banter that the show is famous for. Car Talk’s longtime executive producer Doug Berman in a recent interview with Terri Gross on NPRs Fresh Air explained why the show ended. “He [Tom] felt that he just wasn’t what he used to be,” Berman said. “And he had such an incredible mind that it was really difficult for him.”...

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