Pilates often encourages poses where the hip flexors do a lot of work and will become tight, this is something that's bad because a lot of people struggle with anterior pelvic tilt (which is caused by short hip flexors, among other things).
That's interesting info...I didn't know that and as such I found this informative & interesting. I'm just pointing this out because I don't want people to think this entire thread was completely pointless and devoid of any useful information. Thank you Sir Karksalot!
But....OMG.....nobody is saying aerobics is useless!
As compared to watching tv, playing video games or laying around the house....sure, aerobics is FAR superior in terms of its health benefits and ability to burn fat, but COMPARED to weight-training...the fat-burning of aerobics falls (minute-per-result/benefit-per-effort) short.
If you only have 1-hour per day to excercise, you can get better/more results from weight-training....but that's not to suggest aerobics doesn't have a place in anyone's routine. The phrase we continue to hear again and again comes to mind: MIX IT UP
There are benefits derived from aerobics that are outstanding: circulation, respiratorty, etc...it is important and part of any solid exercise regimen....nobody is suggesting it's irrelevent or useless.
Consider this (taken from Lessons from the Miracle Doctors, Jon Barron):
One of the greatest benefits of exercise is increased production of Growth Hormone in the body (it decreases as we age). The benefits of HGH (Human Growth Hormone) is that it tells the liver to produce Insulin-like Growth Factor (IGF-1). Supplements on the market have been shown to increase IGF-1 levels by at least 20% and as much as 100%...HOWEVER, one 30-minute aerobic session can easily increase IGF-1 levels by a good 100% and a solid session of weight-training can increase levels by an incredible 400-800%.
Score:
Aerobics GOOD
Weight-training BETTER
Balanced mix of both BEST
Personally, I weight-train for a bit more then an hour...at that point my understanding is that the blood-sugars are pretty depleted and since the body can't burn fat fast enough to supply the demand of heavy lifting, it can lead to catabolism. Better put: one hour is ideal. At that point I take a few BCAA's, some protein drink and then proceed to do 30-60 minutes aerobics on the elliptical machine....taking advantage of the low-sugar state and letting some LISS work some fat off.