Gyms, fitness studios and other workout facilities have been slowly getting back into shape since the pandemic devastated their businesses, but the emergence of the Omicron variant threatens to reverse that momentum at the worst possible time.

The big picture: New Year's is typically a big boon to gym memberships, but Omicron threatens to undermine it if Americans decide to stick with now-ubiquitous at-home fitness options.

Where it stands: When COVID restrictions began lifting and vaccinations started in early 2021, Americans grew increasingly comfortable leaving their homes to work up a sweat.

• “The last year has proven that the draw of fitness chains remains as strong as ever,” Ethan Chernofsky, vice president of marketing at foot-traffic tracker Placer.ai, tells Axios. “Should this trend hold into the start of 2022, the wider fitness space would be poised for an impressive return to its former strength.”

Who's at risk: Chains like Planet Fitness, Equinox, Soul Cycle, Life Time Fitness and 24 Hour Fitness thought they had put the worst behind them, leaving stay-at-home brands such as Peloton and Tonal scrambling to build on the success they enjoyed during COVID lockdowns.

Yes, but: Omicron is spreading rapidly just as the new year begins. Home workout equipment, streaming services and fitness apps are readily available.

• The potential return of mask mandates is particularly problematic for gyms that suffered when exercisers had to cover their mouths to work out.
• California has already reimposed its indoor mask mandate through at least Jan. 15 amid a spike in cases. But the California Department of Public Health is making an exception for workouts “if a mask cannot be worn due to heavy exertion.”

By the numbers: 22% of health and fitness clubs have closed for good during the pandemic, totaling about 9,100 locations, according to the International Health, Racquet & Sportsclub Association. Usage declined by more than 50% during the height of the pandemic.

What we're watching: Many Americans have largely returned to normal, and Republican-controlled states are unlikely to restore mask mandates or impose capacity limits on gyms.

• “The business is performing extremely well. I couldn't be more pleased,” Planet Fitness CEO Christopher Rondeau told investors on Nov. 4, adding he expected the “New Year to be pretty spectacular” for his chain.

Our thought bubble: Nov. 4 feels like a long time ago.

The bottom line: Americans have embraced home workout equipment and fitness apps. But many want to work out in person again — which means government restrictions could decide the fate of gyms.