If you’re someone who hates running outdoors in the heat or walking into a steamy cycling studio, there’s a new fitness trend for you: the world’s first cold gym has opened in New York City. The temperature is set at as low as 45 degrees Fahrenheit (7 degrees Celsius), no matter the weather outside. Why would you want to work out in the cold? For starters, you may burn more calories because your body has to work to maintain your core temperature. Cool temperatures may also help build better cardiovascular fitness, since your heart has to work harder to circulate blood through blood vessels and arteries that have narrowed from the cold. But for the same reason, cold gyms may not be advisable for people with cardiovascular issues. If you have any heart health issues, speak with your medical doctor before trying a cold gym workout. It’s also important to always do a proper pre-workout warm-up because your muscles are less flexible in the cold than in the heat.