And some employees in particular are feeling the heat. In yesterday’s Health pages, the Gray Lady took on the recent office trend of replacing desk chairs with exercise balls, and we hope their conclusions will settle some arguments around here.

If you haven’t hung out in an office anytime recently, this might come as a surprise to you. Health-conscious workers – some of them right here in the ZocDoc headquarters – have begun swapping out their desk chairs for exercise balls. The idea is that sitting on a gigantic rubber ball will not only make you appear nostalgic for the halcyon days of kindergarten gym class, but will also force you to improve your posture, and will burn more calories to boot.

In their ongoing Health feature, ‘Really?‘, the New York Times investigates unusual claims like this one. So they dug up some studies on the exercise balls, and got mixed results. According to a 2008 study, sitting on a ball actually does make you burn a few extra calories: four per hour, to be precise, which is around 30 extra calories per office day. That’s nothing to shout about, but it means the claim is technically true.

The author also found some research showing the balls’ effect on posture is neutral. While proponents argue that staying upright and stable on a ball forces you to improve your posture, a 2009 British study found that people on exercise balls slump just as much, and show “poor sitting position.” And a Dutch study from the same time found that while the balls keep your upper body a little more dynamic, they’re harder on your spine.

So in summary, sitting on an exercise ball will help you burn a few more calories, but isn’t any better for your posture. Now forward this link and go tease your coworkers.