Throughout our discussion, we’ve shared strong evidence that being overweight can lead to or worsen OA.  We’ve also shared evidence that losing weight can improve OA significantly.  But there is another factor beyond weight to which you must pay attention if you wish to preserve joint integrity, mobility, and lasting quality of life into old age.  That is muscle strength.

It is very important to understand how muscle impacts the cartilage in your joints.  A group of doctors at Monash University Medical School studied 86 middle-aged adults over a period of two years.  They took precise measurements of the volume of the cartilage that sits atop the shin bone (the tibia).  This cartilage is called the tibial cartilage and is a high risk site for osteoarthritis in the knee.  The researchers wanted to see if muscle strength, body weight, and a number of other factors might be related to shrinking of the cartilage over a two-year period.  They used imaging to carefully measure this cartilage at the beginning and the end of the study. They used a technique called DEXA to measure muscle and fat mass of the arm, leg, and total body.

These doctors found that loss of muscle mass was associated with an increased loss of medial- and lateral-tibial cartilage (show picture) over a period of 2 years. Their conclusion is very important if you want to preserve their joint cartilage and be active all through life.  They wrote, “Muscle mass is an independent predictor of medial-tibial cartilage volume in healthy people in mid-life and is associated with a reduction in the rate of loss of tibial cartilage.”  They went on to say, “This suggests that increased muscle mass may be protective against the onset of osteoarthritis.” To translate, these doctors found that loss of muscle was related to loss of cartilage in the knee located at the inside and outside of the lower leg bone (the tibia).  [Cicuttini, FM, Teichtahl, AJ, Wluka, AE, et al. The relationship between body composition and knee cartilage volume in healthy, middle-aged subjects. Arthritis Rheum  2005;52(2):461-7.

Doctors recently evaluated 18 studies that included 2,832 people with osteoarthritis between the ages of 55 and 74 years.  They wanted to see what the studies implied about strength training and the symptoms of living with OA.  In their analysis, they concluded that: "Resistance training improved muscle strength and self-reported measures of pain and physical function in over 50-75% of this cohort [study group]; 50-100% of the studies reported a significant improvement in all but 1 performance-based physical function measure (walk time)."

[Lange, AK, Vanwanseele, B, Fiatarone Singh, MA. Strength training for treatment of osteoarthritis of the knee: A systematic review. Arthritis Rheum 2008;59(10):1488-94.]

While the exact amount and duration of exercise needed to help arthritis symptoms varies with individuals, it appears that strength training that is done in conjunction with a comprehensive lifestyle program has merit.  Studies like these remind us why the Insulite OA plan puts a strong emphasis on building and preserving muscle mass. We believe that a strength program is critical to maintaining healthy joints. But that is not all.  Muscle mass is linked to healthy immunity and healthy longevity in general.

Michael Schmidt, Ph.D., writing in Beyond Antibiotics, summarizes the influence of muscle on immunity and on survival.  He writes, “The average muscle mass of young, healthy males ranges from 77 to 110 pounds.  An elderly woman may have less than 30 pounds of muscle. (Tipton) Looked at another way, muscle accounts for 90 percent of the cross sectional area in active young men, but only 30 percent in frail older women.  Loss of muscle mass may be one of the key elements associated with the declining immunity common to aging.  This is illustrated by a study of 1,017 men, which showed that declining strength (and lower strength) was the feature most closely linked to survival.”

[Schmidt, MA. Beyond Antibiotics: Strategies for Living in a World of Emerging Infections and Antibiotic-Resistant Bacteria. Berkeley, CA: North Atlantic Books, 2009.]

[Tipton, KD, Borheim, E, Wolf, SE, Stanford, AP, Wolfe, RR. Acute response of net muscle protein balance reflects 24h balance after exercise and amino acid ingestion. Am J Physiol Endocrinol Metab 2002;284:E76-9.]

[Metter, EJ, Talbot, KA, Schrager, M, Conwite, R. Skeletal muscle strength as a predictor of all-cause mortality in healthy men. J Gerontol 2002;57A:B359-65.]