SCIENCE FRIDAY: ABDOMINAL STRENGTH

Walkway to a beach run. Taken by PKSenagore February 23 2017. All rights reserved.

NEW RESEARCH published electronically in February 2018 ahead of print in the Journal Medicine and Science in Sports and Exercise offers potentially encouraging news for those of us worried about chronic inflammation related to abdominal adiposity (translated, this is ‘dangerous belly fat’).
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The article, “Abdominal Muscle Density is Inversely Related to Adiposity Inflammatory Mediators”, was authored by Dr. Rachel Van Hollebeke and colleagues from the University of California at San Diego, La Jolla California. It describes their study in which blood markers associated with the low-level chronic state of inflammation, noted with obesity, were measured and compared with the density and area of certain abdominal muscle groups (rectus abdominus, obliques, paraspinal, and psoas) as detected by MRI (magnetic resonance imaging).

Previous studies informed these scientists that obesity and diabetes lead to increases in skeletal muscle lipid/fat, which translates into less dense muscle and MRI signals that are MORE attenuated.  They knew also that the presence of increased numbers of fat cells inside muscle had been shown to increase the concentration of inflammatory substances in nearby tissues. And that MRI signals of DENSE skeletal muscle with lower amounts of lipid/fat appears LESS attenuated. 

The UCSD group wanted to determine if certain blood markers of ‘adiposity-related’ inflammation in study participants would change according to the amount of lipid/fat in specific abdominal muscles and would correlate with muscle MRI characteristics (density and area).

Data collected, at baseline and at regular intervals over about 8 years, from 1970 participants in a previous larger multicenter study was used. Men and women and individuals of different racial ethnic backgrounds were included. The average age was roughly 64-65 years. Females made up 49% of the group. The mean BMI was 28; 30% were obese. Just less than 50% were former or current smokers, and about as many had hypertension. Blood samples, history/questionaires, body measurements, and imaging studies were administered. There  were other health details (not identified here).

Results showed an inverse (opposite) relationship between “specific adiposity associated inflammatory mediators and muscle density” even after taking into account the amount of visceral and subcutaneous fat. This suggests that regardless of how much ‘bad’ visceral/abdominal fat is present, the amount of harmful inflammatory substances (cytokines) circulating in blood may be less if these abdominal muscles contain less fat cells, and thus are denser.

The paper discussed how skeletal muscle is increasingly being viewed as an endocrine organ that secretes helpful anti-inflammatory hormones or ‘myokines’. Because obesity leads to excess calorie storage as fat in many tissues, including skeletal muscle, indications are that the presence of this excess intra-muscular fat is what causes muscle to become less sensitive to the actions of insulin.

 Insulin insensitivity is a hallmark of Metabolic Syndrome, which is associated with increased risk of diabetes, heart disease, and stroke.

The results of other scientific work, the authors indicate, is that EXERCISE which increases dense muscle may have beneficial effects on health when it comes to reducing whole-body inflammation by reducing body fat overall. And it’s hypothesized that the secretion of myokines that occurs with the contraction of muscles (as in exercise) plays a key role in reducing inflammation as well.

The results of this study, the authors suggest, is that “intervention aimed at improving abdominal muscle density” such as “strength training, may result in lower levels” of “adiposity associated inflammatory mediators and thereby contribute to the prevention of inflammation-linked CVD” (cardiovascular disease).

The bottom line: strength training that leads to increases in lean muscle mass overall may help to fight the kind of whole body inflammation associated with chronic diseases; that which targets the muscles of the abdomen (belly) may specifically help fight metabolic syndrome leading to diabetes and cardiovascular disease.

Losing weight and exercising may be commonly prescribed methods of prevent and combat metabolic disease, but is difficult for many individuals. An alternative method may be strength training that concentrates on increasing the density of abdominal muscles specifically!

The follow-up to this SCIENCE FRIDAY blog will be posted next week. It will include a practical discussion of belly fat and metabolic syndrome.

RUN & MOVE HAPPY!
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https://journals.lww.com/acsm-msse/Abstract/publishahead/Abdominal_Muscle_Density_is_Inversely_Related_to.96987.aspx