"Australian pushups" is a colloquial term for not really working out, born from the idea that since everything in Australia is "upside down," Australians must also do pushups upside-down. So an Australian pushup is just lying on your back and pressing your empty hands into the air. This so-called "exercise" doesn't provide any benefits, but the Australian pullup -- more commonly known as an inverted row -- and regular pullup both offer a host of benefits for your back muscles.
Australians pullups are the same exercise as an inverted row. Lie beneath a sturdy, horizontal bar that's at about waist height when you're standing. Grasp the bar in both hands -- either overhand or underhand -- and keep your body straight as a board. Have your heels on the ground as you pull your chest up toward the bar. Lower back to starting position, keeping hold of the bar, to complete one rep.
Benefits of Pullups
Every type of pullup -- including Australian pullups -- works all the major muscles of your back, including the latissimus dorsi, trapezius, rhomboids and teres major. These pulling exercises also work your rear deltoids -- the back of your shoulders -- and the three pulling muscles in your arms: the biceps, brachialis and brachioradialis.