The invisible effect of body weight on tendons

The predominant view on the relationship between an unhealthy elevated body weight and its effect on tendons, bones and joints is typically grounded in the physical stress effects of body weight. And understandably so, however there is another invisible, less obvious aspect of being overweight that you may need to consider when thinking about your particular condition.

While how much body weight is being physically applied to your tendons, bones and joints is certainly a factor in the development of a tendonitis, there are other consequences from excess abdominal fat on the health of your muscles, tendons, bones and joints (your musculoskeletal system). Excess abdominal fat is not simply a storage depot of excess calories from overeating. There are inflammation-producing consequences of carrying increased body fat you need to think about for your best health.

tape measure for prediabetic waist to hip ratioMost readers know body mass index (BMI) is a common measure of how overweight you may be, however, BMI by itself is not necessarily a reliable measure of the health of your metabolism and the amount of potential inflammation throughout your body. Everyone does not experience chronic inflammation simply from having an elevated BMI. There are many muscular people with an elevated BMI who are very healthy. In order to make BMI more meaningful, waist circumference should also be considered because it is a reflection upon how much health damaging visceral fat you may have.

Visceral fat is the deep fat found in the abdominal, midsection area of the body. Another term you might see describing this, is “central obesity.” In a sense, visceral fat acts as an overactive immune or hormone-producing organ promoting chronic inflammation through the production of biochemicals that are sent out into the bloodstream with an impact throughout the body. The systemic inflammation, promoted by accumulated abdominal visceral fat, can impact a muscle, bone or joint problem you may have and how well it may heal.

When excess fat becomes inflammation-producing, the term “adiposopathy” has been proposed.   This term describes the ill-health from “sick fat.”

How much inflammation and disease is produced by sick abdominal fat has been more fully investigated in the context of cardiovascular disease, but we are beginning to understand its role in the health of muscles, tendons, bones and joints as well.

Systemic inflammation and the metabolic syndrome

So, how do you know if the accumulated fat you may have at your midsection is likely to be inflammation producing? The answer lies in the observation that people with metabolic syndrome are more inclined to have pro-inflammatory fat accumulation at the midsection.

People are said to have metabolic syndrome if they have 3 out of the 5 conditions below:

  1. A large waistline.
  2. A high triglyceride level (or on medicine to treat high triglycerides). Triglycerides are a type of fat found in the blood.
  3. A low HDL cholesterol level (or on medicine to treat low HDL cholesterol). HDL sometimes is called “good” cholesterol. This is because it helps remove cholesterol from the arteries. A low HDL cholesterol level raises your risk for heart disease.
  4. High blood pressure (or on medicine to treat high blood pressure). Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps blood. If this pressure rises and stays high over time, it can damage your heart and lead to plaque buildup.
  5. High fasting blood sugar (or on medicine to treat high blood sugar).

Statistics regarding metabolic syndrome:

  • It is believed a quarter of the world’s adults have metabolic syndrome.
  • People with metabolic syndrome are twice as likely to die from, and three times as likely to have a heart attack or stroke, compared to people without the syndrome.
  • People with metabolic syndrome have a five-times greater risk of developing type 2 diabetes.
  • Up to 80% of the 200 million people with diabetes globally will die of cardiovascular disease.  (statistics source)

In light of this, it is not surprising that approximately 25% of people age 40–49, 35% of people age 50–59, and 43% of those over 60 years of age have inflammation from the waistline fat that occurs in metabolic syndrome. To put it another way, about 25-45% of the adult population is chronically inflamed.

Using cardiovascular study results, it has been determined that average people in the United States are at inflammation levels consistent with a moderate to a high amount. The average middle-aged American is moderately inflamed, however approximately 25% of the US population has high inflammation. The recommended anti-inflammation lifestyle changes to improve health are common sense and well known, diet, exercise, weight loss, and avoiding tobacco use. So easy, but apparently difficult to carry out in light of the statistics above – food and exercise are medicine.

Chronic systemic inflammation and tendon problems

The inflammation brought about by a poor metabolism promotes many medical problems, including pain and negative effects on how well your muscles and tendons work.

achilles tendonA study looking at the tendon at the knee cap suggested waist girth not only has a biomechanical influence on the development of patellar tendon problems, but a biochemical one as well. Other research has shown that Achilles tendon and elbow tendon problems are associated with metabolic syndrome and, generally speaking, local and widespread musculoskeletal pains are more common in patients with metabolic syndrome. (1,2,3)

The emerging belief is that the chronic low-grade systemic inflammatory environment of metabolic syndrome becomes superimposed over areas of strain, or injury, reducing tissue healing and/or perpetuating ongoing discomfort.

This line of thinking is also supported in a recently released study published in Arthritis & Rheumatology, November 2014. In this study, the investigators looked at the relationships between fat mass, muscle mass, fat/muscle mass ratio, metabolic syndrome, and musculoskeletal ( bone/joint/muscle/tendon) pain in a community of adults.

They found that total fat mass and fat/muscle ratio were significantly and positively associated with musculoskeletal pain among females. Widespread pain was more prevalent among those with metabolic syndrome in both normal- and high-BMI subjects, especially among females. Widespread pain was significantly associated with a high fat/muscle ratio after adjusting for confounding variables.

The authors concluded,

Increased fat mass and fat:muscle mass ratio were significantly associated with musculoskeletal pain among women. Widespread pain was significantly associated with a high fat:muscle mass ratio after adjustment for confounders. Understanding the relationship between fat mass and pain may provide insights into preventative measures and therapeutic strategies for musculoskeletal pain.”

While accumulation of excess fat at the midsection is known to be harmful to tendons because of the increased body weight, it is unlikely that increased loading by itself sufficiently explains the development of tendon problems in many people. For example,

lipid deposition is known to occur in tendons, high cholesterol levels have been observed among individuals with Achilles tendon rupture, and the esterified fraction of cholesterol is elevated in biopsies from Achilles tendinopathy subjects” (source)

The question many are now thinking about is whether increased strain from a high BMI is the main cause of tendon problems, or are the local and/or systemic influences of body fat on tendons making them  more vulnerable to problems? Researchers are beginning to examine the effects of certain diets on tendon, muscle, bone and joint pain. This review argues that excessive blood lipids may be an important factor for future clinical investigations.

In many cases, it is likely there is a pro-inflammatory metabolic component to tendon problems, and other musculoskeletal conditions, associated with an elevated BMI. In other words, the structural anatomy, and thus, the integrity of the musculoskeletal system, is changed by inflammation-producing body fat buildup at the waistline, which may make you more susceptible to injury from the increased stress being applied by a heavier body weight. It has been suggested that research in this area supports the idea that, like cardiovascular disease, disease of the muscles, tendons, bones and joints could also benefit from mitigation of cardiometabolic risk factors beyond the reduced mechanical physical load as a result of weight loss.

If you have central obesity and components of metabolic syndrome along with a chronic tendon problem that is not responding well to treatment, it may be because of inflammation due to adiposopathy (“sick fat”).

A heavy body weight is one thing, but think about the influence of invisible  inflammation from excess body fat on your tendons, bones, and joints. Think “beyond Newton“… take action to reduce inflammation-producing visceral fat at your waistline.

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About Robert Creighton

Dr. Creighton is a podiatrist and foot surgeon with over 26 years in podiatric practice treating thousands of patients afflicted with the physiological, physical, and psychological side effects and complications of diabetes and pre-diabetes metabolic syndrome. He believes these disorders present a pressing public health concern that need to be more actively addressed in a multidisciplinary way. Dr. Creighton graduated from what is now the Temple University School of Podiatric Medicine after receiving his undergraduate degree in Biology. He is certified by the American Board of Foot and Ankle Surgery, a member of the American Public Health Association, an American College of Sports Medicine certified personal trainer and a Member of the American Nutrition Association.

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