“The doctor says if I lose weight it will take pressure off of my joints.”
“I need to lose weight, otherwise I will wear down my cartilage.”
These are phrases we hear from patients all the time. And while these statements are not inherently false, they are also not wholly true either.
Consider this example:
Person A is 200 lbs, they are 6’0”, they are 50% muscle mass with 20% body fat. Person B is 200 lbs, they are 6’0”, they are 35% muscle mass with 35% body fat.
Person B will suffer from osteoporosis, tendinopathy, and osteoarthritis, and conditions which contribute to disability and time lost from work at a significantly higher rate than Person A.
Which is to say, we (providers and consumers alike) may overestimate the role mechanical loading (weight) plays in terms of cartilage loss, tendon damage, and bone loss. More importantly it’s the type of weight that determines these conditions.
Recent science explains that a major driver behind inflammation, pathology, and pain is actually an excess of adipose (fat) tissue.
How can that be? Let me explain.
Obesity is recognized as a chronic low-grade, systemic inflammatory state that predisposes to other chronic conditions including metabolic syndrome (MetS), chronic cardiovascular conditions and type 2 diabetes. That should come as no surprise. But less commonly interrogated are the musculoskeletal complications (i.e., muscle, bone, tendon, and joints), that result from obesity-associated metabolic disturbances. Therefore, it is important to know the effects excess of adipose tissue has on the musculoskeletal system.
We know that muscle mass is a key predictor of longevity in older adults, while obesity-induced muscle mass loss (sarcopenia) is a significant risk factor for adverse health outcomes. Muscle is highly plastic, undergoes regular remodeling, and is responsible for the majority of total body energy (glucose) utilization, which when impaired leads to insulin resistance. Insulin resistance can impair muscle integrity through persistent muscle loss and fat accumulation within muscle. This is a common mechanism that cascades an inflammatory pathway that has been implicated in the pathogenesis of tendinopathy, osteoporosis, and osteoarthritis.
One of the fortunate “problems” American’s face is an abundance of food and a relative lesser need to perform physical activity as compared to other cultures. This combination, however, has led to excessive nutrient storage, placing significant stress on our metabolic pathways, and leading to an increase in the prevalence of disease stemming from metabolic dysfunction. This often leads to an excess of visceral adipose (fat) and is linked to tissue damage.
To understand how this happens, we must understand that muscle repair and regeneration is a multi-step inflammatory process involving degeneration, regeneration, and remodeling, ultimately restoring structure and function. The three most active cells in the regeneration of skeletal muscle are macrophages, satellite cells, and fibroblasts. The metabolic complications associated with obesity can result in an inappropriate temporal recruitment of these cells, which ultimately leads to a reduction in structural integrity and functional capacity of a muscle resulting in a pseudo-injury that can become chronic over time secondary to associated oxygen deprivation (ischemia).
If you made it this far in your reading, you now understand that obesity and the cascade of events associated with it ultimately result in uncontrolled processes that, if not addressed, may result in low-grade, chronic, systemic inflammation that, over time leads to tissue injury and degradation.
Which means that we, the practitioner and consumer, must focus on increasing muscle mass through strength training and decreasing overall body fat through nutrition, sleep, and exercise in addition to addressing underlying pain mechanisms and improper loading.
If you really want to nerd out, check out the below graphics:
This information comes from the following resource: Collins KH, Herzog W, MacDonald GZ, et al. Obesity, Metabolic Syndrome, and Musculoskeletal Disease: Common Inflammatory Pathways Suggest a Central Role for Loss of Muscle Integrity. Front Physiol. 2018;9:112. Published 2018 Feb 23. doi:10.3389/fphys.2018.00112
Thanks for reading!
Dr. Jacob Reynolds PT, DPT, OCS Physical Therapist Board Certified Specialist in Orthopedic Physical Therapy Email: firstname.lastname@example.org Follow Jake on Instagram: @theswimmingphysio