The fist bump isn't just President Obama's trademark greeting; it's also the healthier choice.
According to a new study published in the American Journal of Infection Control, a fist bump transmits 1/20th of the amount of bacteria that a handshake does. Compare that to the high-five, which spreads about half the amount of germs spread through a handshake. (The longer or firmer a handshake, the more germs transmitted.)
To test the amount of germs transmitted, researchers immersed a sterile-gloved hand into a container of E. coli bacteria, and, once dry, shook hands, high-fived, or fist bumped another sterile-gloved recipient hand. The researchers then examined the number of bacteria transferred.
In a statement, the study's author David Whitworth of Aberystwyth University in the United Kingdom encouraged the use of the fist bump, as people will never adopt a no-contact greeting:
Adoption of the fist bump as a greeting could substantially reduce the transmission of infectious diseases between individuals... It is unlikely that a no-contact greeting could supplant the handshake; however, for the sake of improving public health we encourage further adoption of the fist bump as a simple, free, and more hygienic alternative to the handshake.
Researchers also dipped the gloves in paint to observe the surface area covered by the hands and, as expected, found that handshakes exposed the most area to the recipient.