Up until 3 years ago, I exercised 3x per week with a trainer and then cardio for 3 days. I was eating more of a Body for Life program and could not lose those last 15 lbs. I also had a hard time keeping muscle. If I overtrained I would lose muscle and not fat.

I was always a sprinter and at that time beat some RPM times on the bike of Olympians who trained at the same gym (I was 38 and they were 25!!!) During that time, I never had stamina. 30 minutes of running would kill me. I dreaded the treadmill because of my lack of stamina. My lungs would burn and I would feel like crap after.

Well, I stopped training because of injury and work about 3 years ago. I still skied on the weekends and some very light biking and did some exercise tapes every once in a while.

I decided to start Atkins because I wanted to lose my stubborn weight, but I decided not to exercise to until I got close to 150. I have put on 12 lbs of muscle and lost around 25 lbs of fat.

Today I jumped on the treadmill for the first time in about a year expecting the worst. I ran for 35 minutes at 6.5 mph and felt great after. As a matter of fact, I don't think I think I ever felt this way, even when I was training in highschool....

What in the heck is going on here?Is this too good to be true? I am still eating between 20-35 gms of carb per day and about 1700-2000 calories per day.

Your thoughts are appreciated.

Could be you had yourself so psyched up on running the adrenaline kicked in. I have seen a lot of people do the same thing. The first day they go back to working out, they out perform what they had done in the past.

Funny story: When I was in highschool I ran track. Over a weekend we went to buy me some track shoes with the track spikes in them. The first 220 we ran, I did at Olympic breaking speed. My teachers jaw dropped. I was never able to do it again. It is amazing what the body can do if the mind stays out of the way

See how you do over the next month or so. If you are still performing at this level or better then I would say it has to be the diet

I'm a newbie, so ignore this post if its wrong.

I see a few things that could explain it.
1. You have lost a significant amount of weight.
2. You have changed your body's fuel from carbs (short lived energy) to fat (stable long burning). That could really have helped you keep a steady energy level.

Congrats, and I bet it continues.

Yeah, I've been going to the gym for a year and saw no improvement in my fitness. A weightlifting class would leave me in agony (and unable to exercise) for a week. All those lunges left me in pain every time I tried to stand or sit down -- not to mention stairs.

Now I'm doing much better.

Personally, I attribute it to increased protein. I think that before, on my controlled-calorie diets, I just didn't consume enough protein to help my muscles repair themselves after a strenuouns workout.

Just my theory, based on the fact that I'm eating more protein than ever before -- but I honestly have no idea for sure what's REALLY happening.

Low carbing has made me healthier and stronger it seems too.

LC'ing certainly hasnt hurt my running. I am easily managing 7 or 8km 4 times a week.
My high rep weight training does seem to have suffered a little. Just cant squeeze out quite as many in a set as i was able to before.
One aspect of my training that has been totally clobbered is my swimming. Before LC'ing i was managing a solid 2km swim 3 times a week. NOW i can barely get throught 250m. I have been trying to figure this aspect out for sometime. Only theory i have come up with is that swimming is simply a level of energy consumption that is above the replacement rate provided by FAT burning.

I have to agree with the lack of soreness with the weight training though. Even after some serious exertions with the weights i dont pull up anywhere near as sore the next day as i used to. You maybe right, perhaps all that extra protein really does do the trick.

Cheers
Jason