We had Phys Ed all through school (I suppose it was 'recess' in early grades) and it was/is still in place.
If one was involved in a team sport such as Track & Field, Soccer, Football, Basketball, Hockey, Gymnastics, Wrestling, Cheerleading, Swimming, Diving, etc., one may opt out of Phys Ed, class. One had the option to replace a Phys Ed class or Study Hall for an elective College Prep course, naturally.
It's a great concept, in theory, to mandate physical fitness as a part of ones education (no doubt, beneficial). But so is Home Ec, Shop, Sex Ed, Accounting, Philosophy, Art, Music, Computer, other Languages, etc. Those are electives in addition to the established curriculum basics: Math, Science, History, Language, Geography.
The flip side would be at what cost? Which class(es) should be forfeited for the sake of a structured 45 mins of exercise? Perhaps having a mandatory 20 mins at the start of each day for all students of all levels, to participate in an exercise routine, that includes stretching, movement, and some cardio would be appropriate? I see a mandatory Phys Ed test for all levels as a possible solution, one would not be "passed" if they failed at the basic requirements. This would mean that either through formal instruction, participation in a team sport, or on their own time..they could would be fit enough to pass.
How many hours should a child be expected to be at school? If one were to include all necessary classes, we're talking about a 10 - 12 hour day. It simply isn't feasible. It's cost prohibitive. It's not reasonable to expect younger (or older) students to have that long of a day.
Some want to ban fast food restaurants from serving deep fried foods. Some want to abolish all sugar-laden soft drinks from school cafeterias or vending machines. Some choose to place blame on school systems, the government, or independent, free-market corporations for not teaching children how to be healthy and fit. Some want to ban the bright, fun color schemes and cartoon characters that fast food restaurants use in adverts..due to children being attracted to them. Placing candy and sweets out of the lower shelves of stores, so children won't see the candy and buy it..This is laughable since this should be the responsibility of concerned parents and guardians of all children..yes?
If a parent is active, fit, promotes daily exercise, selects nutritious and balanced foods for meals, doesn't partake in unhealthy habits (such as alcohol, drugs, substances, cigarettes), if parents stepped up to the plate and educated their own children re: safer sex, taught them how to file a tax return, how to prepare meals and manage a household by example..then many of the elective courses wouldn't have to be. Anyone who is opting to reproduce and doesn't have the ability to teach by example..really should look in the mirror vs pointing a finger at what schools are not emphasizing.
For as long as I have been alive, there has always been a structured Phys Ed program in place for all levels of students. If the student refuses, or is disinterested in keeping fit..it's not the school's fault for not pressing the issue. Personal responsibility and disipline trump (attempted) force re: ones own health and well being.