While you can’t choose your family, you can choose your friends and science tells us that you better choose carefully. Numerous scientific studies demonstrate that your social circle affects more than which post-run brunch location you go to. Your social circle also affects your health. Perhaps the most famous of these studies is a 2007 study published in the prestigious New England Journal of Medicine entitled “The Spread of Obesity in a Large Social Network Over 32 years”.
They tracked, well more like borderline stalked, this famous cohort of subjects for over 40 years. While the primary goal of this massive research endeavor was trying to figure out what environmental and genetic factors contribute to heart disease, they also studied known risk factors for heart disease like obesity. Included in these “factors” was a massive amount of information about their social networks, everything from who they hung out with on a local level and who their close friends were that lived at a distance.
If your friend (in real life, not just on Facebook) became obese, you had a 57% increased likelihood of becoming obese. An obese sibling…40% more likely or if your spouse was obese, there was a 37% increase in obesity likelihood. Fat neighbors were not much of an influence. Thus, the increased risk of becoming obese was unrelated to physical location as people in the same neighborhood did not show similar increases in likelihood to developing obesity. As the authors of the journal article conclude, “Network phenomena appear to be relevant to the biologic and behavioral trait of obesity, and obesity appears to spread through social ties.”
So, does that same social network phenomenon apply to physical activity? Surprisingly, it does. In another study, the physical activity levels of 3500 Air Force Cadets, who are randomly assigned to different squadrons of 30 peers (ie a social network) when they enroll in the Academy, were tracked prior to and after enrollment in the Academy. The major conclusion was that, yes, who your social network was mattered; cadets that had peers in their squadron who performed poorly in high school fitness were more likely to fail the Air Force Academy fitness test and vice versa. These students spent a majority of their time with fellow squadron students, except, importantly, when they are in the classroom and doing physical training.
So, you can’t just blame it on a bad PE teacher. You could however blame the most unfit in the squadron, as those cadets had the strongest influence on others fitness, dragging them down towards their lower fitness level. This was not a minor effect either. Cadet’s own fitness was 40-70% determined by their peer’s fitness. Of course, this is a very unique population among people whom were not socially close before the experiments, but the findings are a cautionary warning. Perhaps the adage that you are the average of the five people closest to you in life has some merit. Then again, maybe building a strong online social network that supports healthy behaviors can also help. Well, maybe not.
In a meta-analysis study published in the journal of Medical Internet Research, Carol Maher and colleagues found that online social networks were not very effective at helping change various behaviors including; physical activity, weight loss, eating behavior, and quality of life. Don’t lose all hope, though, as the author’s emphasize that the research is in its infancy and the potential of online communities remains huge, we just need to find a way to tap into that. The data does suggest that online communities will never be as effective as in person. Failing to meet your running partner at 5:30AM on a weekday would seem to have a lot more social consequences than failing to post an update on your run on Facebook or Twitter. So, choose your friends wisely, ones that enrich your life to make you a better, faster and healthier person.
Matthew Laye has a PhD in medical physiology and is fascinated by how exercise protects against so many different diseases. He is an Assistant Professor at The College of Idaho in the department of Health and Human Performance. When he is not in the classroom or the lab he can be found on the roads, trails, or in the mountains exploring the outdoors. He sports a marathon best of 2:23 and a 100 mile best of 13:17 and blogs at https://layeingitdown.wordpress.com/ on occasion.