About 2 months ago I took a fitness assessment (Active Metabolic Assessment) that involved taking measurements (heart rate, etc.) while on an elliptical machine. I did 15 minutes on the machine to establish a base line, had a short rest, and then did another 15 minutes at increasing resistance every 2 minutes. With 20 seconds to go my knees buckled and I was not able to continue.

After 2 months of almost daily exercise the same thing happened about 45 minutes into a group fitness class today. I was on an elliptical machine doing interval training and my knees buckled again without warning.

I am hoping to avoid this happening again and don't have any history of problems with my legs or knees. I am not sure if this is being caused by diet (currently averaging 1,200 calories and 100 grams of Protein per day), simple exhaustion, or possibly orthopedic issues. Looking for suggestions on whether I should see my PCP, my nutritionist, an orthopedic doctor, or simply avoid elliptical machines.

Well, since you probably like having legs and knees, I would suggest you do see an orthopedist, or at least your primary physician. I have many orthopedic issues, some caused by spinal discs pressing on nerves. I am officially diagnosed as a high fall risk and am well aware of what damage a hard fall can do. One thing you don't want to do is dismiss your symptoms or self diagnose. I hope you get a resolution to your situation.

Twice I have fallen in the bathroom and hit my head on the tub and gone out like a light.

There was a bariatric brother on here about two years ago who said he got dizzy and fell in the living room, breaking his jaw on the edge of a coffee table. Please take care.

One thing you don't want to do is dismiss your symptoms or self diagnose. .

I couldn't agree more. I have absolutely no idea what is causing this problem and will make an appointment with my PCP who has been very helpful with other issues.

In the meantime I will limit my use of the elliptical machines and hit the pool instead. Thanks!

When is the last time you had your Vitamin levels checked? That is probably where I would start. And any chance you aren't getting enough Fluid? Yes, meantime, avoid elliptical or anything that would overstress your major muscle groups.

When is the last time you had your Vitamin levels checked? That is probably where I would start. And any chance you aren't getting enough Fluid? Yes, meantime, avoid elliptical or anything that would overstress your major muscle groups.

My vitamin levels were just checked a few weeks ago and my surgeon said everything looked good. I always bring my Water bottle to the gym and drink about 32 oz while I am there.

Its really odd because nothing hurts when this happens, my legs just give out. I sat down for a few minutes to rest and my legs started working again. I even finished the rest of the fitness class (rowing machine and stretching).

This is probably unlikely but the thing that came to my mind is rhabdomyolysis.

Start with ortho and go from there. Sometimes even having the surgery can't undo the strain we put our limbs under for so many years.

Start with ortho and go from there. Sometimes even having the surgery can undo the strain we put our limbs under for so many years.

You are right about putting our limbs under strain. I had some pain in my right knee walking up stairs yesterday after the gym and just remembered I was diagnosed with osteoarthritis in my right knee about 5 years ago. I have had no issues (until now) after completing physical therapy back then. I called my insurance company's 24 hour nurse hotline and the nurse suggested starting with my PCP to rule out other issues and to discontinue use of treadmills and elliptical machines in the meantime.

I was hoping to take a break from doctors in 2016, but I guess that is not going to be possible.

That may be the diagnosis. I was dx'd with osteo in my left knee years ago. A few years before my WLS I was also told I had very slight indications of it in my right knee as well. This past summer (~6 -8 months post-op) I was having a lot of knee pain. After a few visits to the ortho, it was discovered that the osteoarthritis is now actually worse in the right knee. I am under doctors orders to avoid the treadmill and and high impact activities. I did the long term, no steroidal injections over the summer as well. My knees don't hurt anymore, I just can't do high impact workouts.

Here is an update. I went to my PCP who reminded me that I was treated for osteoarthritis in my left knee 5 years ago and that the pain in my right knee could be the same problem. He ordered an x-ray of my right knee and referred me to an orthopedic doctor. The x-ray showed a mild case of osteoarthritis in my right knee. The orthopedic doctor didn't find any other things wrong with my knee and referred me to a physical therapist. The physical therapist noticed that the muscles in my right leg were weaker than the muscles in my left leg and has set up a program to strengthen the muscles in my right leg and to increase flexibility. I have been working with the physical therapist for the past few weeks and he is going to have me get on an elliptical machine tomorrow during our session. I am a little apprehensive about getting back on the elliptical machine, but I am glad to be making progress.

Just two words: swimming pool.

Just two words: swimming pool.

I have also been hitting the swimming pool at the gym a few times a week. Its been tough getting all of this exercise and physical therapy in, but I have made it a priority. Swimming laps indoors is not my favorite, but I am looking forward to the outdoor pool opening up after Memorial Day.