©ABC, 2014. Donald Faison and Zach Braff give each other a fist bump in the TV show, Scrubs.
This article is all about fist bumps. And diseases. And bad science.
For the handful of you who are culturally naïve, let’s quickly describe the fist bump itself. It is a greeting, in lieu of a handshake, which is performed when two individuals acknowledge each other with a closed fist gently tapping each other. There are, of course, all kinds of flourishes and embellishments added to a fist bump, which are unique expressions of individuality. I like the hand explosion after a fist bump, but that’s probably uncool.
If you thought fist bumps are a recent cultural creation, you’d be wrong. Apparently, Greek charioteers did it. And motorcycle riders who pulled up next to each other at red lights have been doing it since the 1940’s. The gesture has been relatively popular in the American game of baseball for at least 50 years. President Barack Obama regularly fist bumps instead of offering a handshake, even with his wife, Michelle. Researching this story, I always thought it was modern and fashionable, but I find out it’s antiquated, but possibly still fashionable.
During the 2009 H1N1 flu pandemic, many medical professionals recommended that healthcare workers greet each other with the fist bump with colleagues and patients rather than the traditional handshake. My anecdotal observations are that I’ve done more fist bumps in the last two or three years during visits to hospitals and physicians than I had in my whole life before (which may have included approximately 0 fist bumps , but I’m not cool). I had a 5 day stay in a hospital a couple of years ago, and not one single nurse, physician, surgeon, attending, resident, janitor, or nutritionist shook my hand. Not one. But I certainly got the fist bump every time, even when I extended my hand for a handshake (I was bored in the hospital, so I started to experiment).
After observing this huge increase in fist bumps, I’ve always wondered if the fist bump had any real advantage over the handshake in reducing spread of diseases. Most healthcare workers are fastidious about washing their hands (many hospitals have hand sanitizer dispensers nearly everywhere on every floor), so I can’t imagine viruses and other pathogens have much of an opportunity to move from one person to the other. If only there was some science to back up this behavior change in healthcare workers.
A group of researchers from West Virginia University recently published a very small study that concluded that substituting the handshake with a fist bump could reduce the transmission of bacteria. Again, given the focus of many public health officials to “wash your hands” to reduce conveyance of diseases by the hands, I probably would have accepted the research and move on. I mean seriously, why would a skeptic write an article about fist bumping if it were so easy. And it isn’t.
Basically, the study showed the following results:
- The study first got some basic data about 10 subjects. Yes, 10, but it gets worse than that. Unsurprisingly, they found that the average surface area of an open hand, 194.88 cm2, was significantly greater than the surface area of a fist, at 50.75 cm2. They also found that a handshake lasted about 0.75 seconds vs 0.25 seconds. I’m a little skeptical that the researchers could even measure a time of “0.25 sec” accurately and consistently, but then again, they didn’t provide any statistical analysis, so it’s possible they didn’t even try.
- But here’s where it got a little less scientifically plausible. Two (you’re reading that right, just 2) healthcare workers walked around the hospital touching objects and shook the hands of 20 coworkers. Then the palm of the hand was placed on an agar plate (the typical method of culturing bacteria) for five seconds.
- Then the the two subjects walked around the hospital, repeated the experiment, but this time doing fist bumps with their 20 coworkers. Then the closed fist was cultured in the same way.
- The authors found that the total number of bacterial colonies was four times greater with the palm than with the fist. However, the number of colony forming units was 187.5 vs. 42.5 (about 4X), which mirrors precisely the 4X difference in palmar surface area versus closed fist. In other words, based on surface area alone, this is the result we would have expected. And, the authors could find no statistical difference between the numbers.
This is some very weak data. In fact, the authors conclude, “the study is limited by our small sample size and it could not assess statistical significance.” I honestly cannot figure out how this article got published, because the Journal of Hospital Infection is a fairly high quality peer-reviewed journal with a moderate impact factor of 3.22.
This might end the story, and you would think, “once again, why is a skeptic writing about this?”
Because the press took this small study, that really provided no important evidence for fist bumping in a hospital, and blew it way out of proportion:
- Why A Fist Bump Is More Hygienic Than A Handshake: A Dap Is 4 Times Less Likely To Spread Bacteria – The Medical Daily.
- The Fist Bump Manifesto – James Hamblin – The Atlantic.
- Want to spread fewer germs in hospitals? Ditch the handshake, go for a fist bump – Med City News.
- Doctors encourage ‘fist bump’ over handshake to prevent illness – CBC News.
- When Is a Fist Bump Better Than a Handshake? – National Geographic.
It’s incredible that all of those sensational headlines were based on a flawed, small study that the study authors themselves admitted didn’t really show much. I read each of these (and many others) articles, and not one of them provided any type of critical analysis of the West Virginia University study. Not one.
If a healthcare worker wants to give me a fist bump when I’m coming in to have my blood pressure checked, that’s fine. It makes me feel kind of “groovy” (need to bring back that word). But as for evidence that fist bumps reduce transmission of pathogens? I’m not convinced. There are as many bacteria on the back of the fist as there are on the palm (per square centimeter), but because the fist has a smaller surface area doesn’t mean that there’s 75% less transmission of infectious diseases. This study just doesn’t give us any information about that.
So, fist bump or not? Do whatever makes you happy. I’m just not sure it really reduces transmission of disease.
Key citations:
- Ghareeb PA, Bourlai T, Dutton W, McClellan WT. Reducing pathogen transmission in a hospital setting. Handshake verses fist bump: a pilot study. J Hosp Infect. 2013 Dec;85(4):321-3. doi: 10.1016/j.jhin.2013.08.010. Epub 2013 Sep 19. PubMed PMID: 24144553.
