This works again by manipulating the leverage of your body, only this time by putting your feet on an elevated surface instead of your hands. (neatstrength.com)
Place your hands on an elevated surface like stairs or the back of a bench, and complete a push - up with your arms close by your side. (nerdfitness.com)
Lastly, your carrier or car seat should not be placed on elevated surfaces or shopping carts. (sfnewborncare.com)