Help! Do i need to switch up my workouts?

I started at 401 lbs but was around 350's maybe when i joined the gym. I am now 328 lbs. Anyway i used to do 5 minutes literally on the elliptical and like maybe a 1.5-2.0 mph on the treadmill and i would get to my target heart rate of 163 and be winded. Now i am doing 20-30 minutes on the elliptical and my old speed of 2.8-3.2 isn't cutting it.. my HR isn't as high as it should be to get the appropriate benefits.. now i am doing over 4.0 mph  at a level 6 to get my HR where it needs to be. On the treadmill it is taking at least a 2.0 incline and 3.2 mph or so to raise my HR to 163 or higher. Is my body used to these exercises now and i need to do something differently or go along with the higher intensity and hope i don't fall over?? LOL

I just cannot believe at 328 lbs i was able to speed up this quickly i mean the speeds alone and doing a 17 minute mile on the elliptical for me is pretty impressive.. was also doing 26 minute miles now it is 19-21 minute miles. I got in almost 9,000 steps today my goal is 8,000 with my ultimate goal being at 10,000. I have done circuit already too.. i just don't know if i need to switch things up and if so how to go about it??

Hi,

You are doing great.  Now is the time to start strength training. Building strong lean muscles not only will strengthen your bones, heart and inner core but it will also increase your metabolism which will also help you lose the fat.  Cardo exercise is super but needs to be combined with building your muscles. 

I have been working at Curves and have studied through Cleveland Clinic to on what makes us tick as women. How do we metabolize foods, how we are made and what will help us succeed.  So, what I am saying is not bunk but researched and documented knowledge.

So higher intensity will come in time as your muscles get stronger and healthier. Keep me posted.

Totally normal.  I don't think it matters how much you weigh in this case-your body is becoming more efficient and you're going to need more intensity to get that heart rate up to burn fat.  Go for it!  I am so so so proud of you.  

I would look into intervals.  Where you spend a minute or two at a higher speed, then bump it back down for a minute (that is just an example-play around with it).  I love interval training it actually burns more fat.  Also-look at add some weights to the game if you can.  They sell inexpensive wrist and ankle weights that just fit right on over your hands, wrap around your ankles.  That will help you burn more too because weights always bring intensity to the game.  I'm talking 1 lb wrist and ankle weights to start off with-don't go too crazy.  Heck, I borrowed one of the kids backpacks, stuck a flat 5lb weight from our barbell into it and wore it working out on our Tread Climber.  Whew!  But it works so well.

Have fun with this!  It will totally pay off after surgery because you have already started this journey and you will know how your reacts to all these workouts.