For many avid exercisers, the power of the group is key to achieving their fitness goals. Whether you’re inspired by the encouragement of your instructor or your competitive side keeps you in step with your peers, fitness classes can be an effective part of any workout plan. Among the public, enthusiasm for group exercise is on the rise: In a recent study, the American College of Sports Medicine called these classes a defining fitness trend of 2018.

But participants in group fitness classes may share more than camaraderie and common health goals. Each time CrossFitters grab a barbell or spin fanatics adjust the resistance on their bikes, they could be unwittingly acquiring what someone else left behind: bacteria.

Think about the filthy facts for a second: Human hands are hotbeds of microbes, and group workout equipment can come in contact with dozens of them every day. Plus, sweat combines with bacteria when it reaches the skin – and participants in these classes work up plenty of perspiration. However much group fitness helps with inspiration, it may be even more conducive to infection.

Just how many germs could be lurking on equipment used in these classes? We decided to take this question into our own (gloved) hands, swabbing equipment from four of the most popular group fitness classes: barre, CrossFit, spin, and hot yoga. Our bacterial tests reveal the total number of microbes that appear on various workout tools, and which classes attract the most harmful germ varieties.

Ready to see which group fitness classes entail the greatest risk of getting sick? Let’s do this.

Your Gym’s Most Contagious Classes

We measured the bacterial content of swabs for each class in colony-forming units (CFU), a measure of the volume of microbes in a given sample. We gathered three separate swabs from each class and averaged CFU totals to determine a single representative number. Finally, we compared the average for each class against a pretty repulsive reference point: the number of CFU on the average toilet seat.

Apologies to CrossFit fans everywhere, but germs appear to be a major part of getting “swole” by this method. Our findings show barbells used in CrossFit classes were inhabited by 48 times more bacteria than the number of bacteria living on a toilet seat. For a program that prides itself on meticulously recording workout data, that number should give its proponents pause.

Yogis who like their classes hot also have a reason for concern. When we swabbed mats used in hot yoga classes, the CFU count clocked in at over 25,000 – eight times the toilet seat total. Although many studios wipe down their mats at the end of class, it seems the safeguard is insufficient to keep bacteria at bay.

While other classes studied were not entirely devoid of germs, they did have much better records. The resistance knobs on cycling bikes had negligible germ counts, despite getting tweaked at least a couple of times during each class. The wooden bar that forms the basis of barre classes had similarly minimal microbes. That’s particularly impressive given how often these bars come in contact with feet during stretches, for which many participants are barefoot.

Which Microbes Appear Most?

While some bacteria totals above were striking, not all germs are created equal. In fact, some bacteria are beneficial or basically harmless, whereas others contribute to serious illnesses. On the CrossFit barbells, for instance, 47 percent of bacteria were bacillus, which can either aid or injure humans. But 31 percent were gram-positive cocci, which are associated with skin infections and diseases like pneumonia.

Hot yoga mats had an even greater proportion of these pernicious pathogens, with 52 percent of bacteria registering as gram-positive cocci. This finding helps explain why some experts have become so fearful of skin infections from shared mats they recommend using the floor instead if you forget your own. These bacteria also dominated spin class samples, but you can’t drag your bike to class.

Barre classes did not feature any gram-positive cocci, but their germs were no laughing matter either. Nearly all gram-negative rods affect humans negatively, and they’re responsible for many respiratory infections. To make matters worse, a growing number of these pathogens are resistant to antibiotic treatment, a source of increasing concern for the medical community.

The Path to Fewer Pathogens

In light of our findings, what can fitness class fanatics do to reduce germ exposure? Our first suggestion is as obvious as it is important: Wash your hands as quickly as possible after leaving class. Even if you take this precaution already, you might consider extending the time you spend at the sink: Physicians recommend washing thoroughly for at least 20 seconds every time.

Another tip to prevent contagion might require arriving to class a bit earlier: Wipe down equipment before you use it, instead of assuming the last user left it sufficiently sanitized. Repeat the process once you’re done, of course, out of respect for your fellow exercisers. After all, that sense of community spirit is part of group fitness classes’ appeal: Exercisers supporting each other as they pursue better health together.


We collected data from swabs of three classes for each workout included above. We then averaged the three results for each class type to determine the colony-forming unit figures presented. The specific varieties of bacteria discussed are standard inclusions in microbiological tests of this kind.

Fair Use Statement

Want to share our results with your gym buddies? You’re welcome to use our findings and images for noncommercial purposes. We do ask that you attribute us to our work by providing a link to this page. In this regard, content is a lot like bacteria – when it spreads like crazy, it’s good to know where it’s coming from.

About Us

Here at EllipticalReviews, we do in-depth research into fitness issues and products. We help users of all fitness levels find workouts and products suited best for their needs. Check out our recent review of the excellent NordicTrack FS7i.