Originally Posted by Larry Wright
I started CF and the Zone in Dec. I weighed around 375-380 lbs. I am now 313lbs. I am following Starting Strength and am now strictly Zoneish/Paleo. My goal is continued fatloss while building muscle and strength. I completed the physical agility test for the Sherrifs dept. on Sat. I passed the test which is amazing in it self. Couldn't have done it 6 months ago. However, I was told by the administrator that I needed to work on my aerobic fitness if I am accepted. I am still a big guy at 6'2. I don't want to tear my knees up. I've been doing some sprinting along with walking. Will the sprinting do the trick? Am I being to impatient? Is there something else I can do or need to consider?
If you've been told to work on your aerobic fitness then the answer is no, sprinting will not do the job. I presume that as you've completed the physical agility test you're anaereobic conditioning is already adequate for short bursts of activity so it's stamina that you need to improve and that's going to be a problem for someone who weighs 313lbs.
The first thing you need to do is get your weight down to a point where you can do some distance running without wrecking your knees and the most important aspect of achieving this is getting your diet under control so you can create a small negative energy balance and that's just a matter of applying some common sense and willpower to your food choices; lean meat and fish, vegetables, fruit, nuts and seeds are good, donuts are bad etc.
Distance running is going to be out of the question until you've lost some weight so I suggest you get a bike and just concentrate on building a good base level of aerobic conditioning which will help you lose some lard and limit sprint training to once or twice a week to save your knees. Any bike will do, it doesn't have to be expensive, in fact a cheap single-speed like most of us rode as kids is perfect for the job as it means you'll be forced to get out of the saddle and sprint more than you would if you had gears.
Once you've dropped some weight and you're aerobic conditionings improved you should start doing some running in the usual beginners mix of walking and running but if you feel any knee pain cut back on the distance running and get back on your bike so you can continue working on your aerobic conditioning and fat loss without risking injury.