The rare mushroom Cordyceps sinensis has been used in Chinese medicine for more than 2,000 years, mostly to boost immunity and speed recovery from illness. But apparently that’s not all it’s good for: Now there’s evidence it can also make you more fit.

Researchers at the Rippe Lifestyle Institute in Shrewsbury, Massachusetts, gave a group of 131 men and women ages 40 to 70 a 3-gram cordyceps supplement every day for 12 weeks. At study’s end, the participants had raised both their aerobic capacity and their endurance— without upping their exercise level.

That’s good news for anyone who’d like more get-up-and-go or who needs help starting a fitness program after a long period of inactivity. The supplement used in the study, CordyMax, is available at www.pharmanexusa.com.