July 2015 PSA: Don't Thrash Your Knees!!

"Force is equal to mass times acceleration, and acceleration is gravity's 9.8m/sec./sec..  Gravity remains constant so the greater your body mass, the greater the resultant force on your joints...heavier people have LARGER forces on their knee joints and it's those forces that contribute to premature joint wear."

That's my politically correct and sensitive spiel for when my heavy brethren ask me why their knees hurt when and after running.

An article in a 2005 issue of the Journal of Arthritis and Rheumatology stated that there is a 1:4 pound relationship between one's weight and the forces sustained in the knee joints when walking...and that's just WALKING!  High-impact exercises such as jumping and running can subject your knees to forces up to 7x your body's weight.  My point is that it doesn't pay to participate in high-impact activity when you have excessively more weight than you need on your body.

A 2012 publication in the Journal of Inflammopharmacology concluded the following on the relationship between obesity and knee osteoarthritis:

"Recent prospective studies demonstrate obesity as a primary risk factor for incident knee osteoarthritis. The potential mechanisms to link obesity and knee osteoarthritis, as both a biomechanical and metabolic condition are strongly linked."

When it comes to exercise, there are many non-impact exercises one can do to burn calories and lose weight.  When I see weight-loss programming that utilizes high-impact movement as its main mode of exercise (for obese individuals), stupidity and ignorance come to mind.  The sad part about joint wear and arthritis is that the onset of symptoms is pretty abrupt; many don't know until it's too late.  Patients have told me that up until the moment their knee blew up like a grapefruit, they never felt any symptoms. Younger people can go a long way before feeling symptoms but I've seen enough patients in their 40's and early 50's suffering from arthritis that I know everything one does during their youth eventually catches up!

SOLUTIONS

I'm all about solutions so the following is a list of some light and zero-impact exercises one can do for strengthening and weight-loss:

• Chair or Table Push-ups 
• 1/2 Squats
• Inverted Rows
• Walking
• Low Impact Aerobics
• Water Exercise/Aerobics 
• Conventional Dumbbell and Stretch Band Exercises (squats, shoulder press, biceps curls, etc.)
• Suspension Training (TRX)
• Stationary Heavy Ropes
• Upright or Recumbent Bicycling
• Elliptical Machine
• Rowing Machine

There are always exceptions and special situations.  If one is categorized as obese but has a single digit or low body-fat percentage, high impact exercises can be indicated.  If an obese individual is suffering from a serious illness that trumps arthritis, and high-impact activity is their favorite or only mode of exercise, then more power to them...they can jump and sprint until the sun goes down!  If one is clinically heavy and doesn't have any compelling reason for high-impact exercise, I suggest they select low-to-no impact exercises.  Their knees will thank them for it.

Happy training,

DAVE