Sue Fox can’t teach her stand-up paddleboarding classes for more than a couple weeks without developing a six pack.

“It’s like — boom! — every year, I tone right up,” said Fox, who oversees Tumalo Creek Kayak & Canoe’s SUP program.

But that doesn’t mean everyone sees those results. New research commissioned by the American Council on Exercise draws a strong correlation between one’s level of experience using a SUP and the quality of the workout he or she derives. The two new studies, which examined cardiovascular levels and core muscles activation, provide some of the first scientific research into a popular sport whose health benefits so far come mostly from aficionados’ testimony.

Watching Fox glide along the Deschutes River just north of the Old Mill District, the difference between someone who has been SUPing for eight years and a newbie is apparent.