Yes - it sounds like a stupendous idea indeed, doesn't it? Pushups that heavily tax the core of all things - that alone is a hard concept for most to stomach, but LEGS as well?
Pushups are primarily a chest, arm and shoulder exercise as far as most trainees are concerned. And while they do provide a great workout for the chest and arms, they also work the back (including lower back) and core heavily - and as I said, certain types of pushups will work the legs as well. And some pushups are pure CORE exercises - with the rest of the body merely playing a supporting role as it were.
I fitted the core pushup into my workout today - I did this, and another style of pushup as "rest" exercises between my main two upper body exercises, which were pull-ups and handstand pushups. What I mean by "rest" exercises is that I did a set of these exercises while "resting" between the main exercises - not something I usually do, since it cuts down on my ability to focus (and recuperate for) on the next main exercise, but I was feeling unusually peppy today, so figured I'd give it a shot.
One such pushup is the "extended arm pushups", where instead of putting your hands at shoulder level beneath the chest, you extend them all the way out over your head, and THEN do the pushup. The form is hard to explain in an email, but let me just say that chest/arms (while taxed) are NOT the limting factor for this pushup - for those that have never done these before, you'll be finding your lower back/core is what is really being worked on this one - don't be surprised if you end up with sore abs upon doing these!
Another example would be the table pushup, wherein you simply get into the position of a table (on your hands and feet), hold for a bit, and then push back to the starting position. This is a superb tricep builder, but it also works the thighs, butt and hamstrings heavily if done correctly. And so forth. . .there are just too many examples to list out here.
Now, does this mean that pushups are ALL you need to do for your entire body? Not really - not by a long shot actually, but the fact stands that you can get a pretty decent overall body workout in less than 15 minutes or so simply by doing different styles of pushups.
And no, these aren't "easy" exercises by a country mile - but I think you'll discover that for yourself when you try them! Thats a GOOD thing though - remember hard work is what brings real results.
OK, I'm outta here for now. Until next time - train hard - and keep me posted on your progress on the workouts you guys have been doing!
PS: All the different pushup variations that you need to know about can found right HERE: - http://rahulmookerjee.com/index.php/articles/83-fast-and-furious-fitness-the-book - grab your copy ASAP.