I don't have much experience... but definitely helps with respiration. I don't get winded from my asthma.. and i can go longer without needing a rest.
I am extra active (that can be compared to cardio) for 4 hours a day 4 days of the week and I've always had a 4 pack stomach (slightly defined.. not ripped lol the bottom 2 of the 6 pack I can't seem to get) but diet plays into it too. If I avoid dairy, my stomach is well defined. If i drink more than 3 coffees with milk, forget it. I have a fast metabolism, but most people with average or slow would really have to watch.
As for hormones... i was always estrogen heavy and just had a uterine ablation so there's a 90% chance i wont get periods anymore. Today was what I think is supposed to be my period lol its about that time but light spotting and no pms, no break outs on my chin, no candy cravings (i did crave a caramel latte with no extra Sugar - just the sweetness from the caramel syrup and i did indulge) no moodiness and a slight headache that went away after i had lunch. An ablation wouldn't change the hormonal aspect of that... it only stops the endo lining of the uterus from growing because its cauterized. So, something happened in those last 2 weeks of Iodine that balanced my hormones enough to not have pms or turn into a homicidal maniac. I've never NOT had pms except when i was pregnant.
What if a guy had low testosterone because he blew out his adrenals 20 years ago with anabolic steroids?
Would Iodine kick start it?