A series of Friday-afternoon fitness courses at the Fitness and Recreation Center is gaining popularity among Boston University students who are short on credits but willing to fork over $3, drawing so many students that instructors have had to turn some away.

“Happy Hour workouts are an opportunity to try something new and a great way to gear up for the weekend,” Fitness Coordinator Rossella Avitabile-Muller said.

Five students were turned away from FitRec’s Happy Hour Workout last Friday, with the Pilates Mat class exceeding capacity with 33 in attendance. FitRec now offers the $3 Happy Hour workouts each Friday from 4 to 5 p.m. in L137 introducing students, faculty and FitRec members to the variety of classes offered.

“We hope to showcase every fitness opportunity,” Avitabile-Muller said.

The Pilates class last Friday attracted more than 30 students. The class was scheduled to cap at 30 participants, but Avitabile-Muller allowed three additional students in. The Pro Shop had to turn five students away from signing up for the class, according to Pro Shop worker Laurie Natale. She said some students have already signed up for all the Happy Hour sessions for the rest of the semester.

“It’s great,” the College of Arts and Sciences sophomore said. “If I was not working, I would try to go. It’s a good range of activity that’s only $3.”

Avitabile-Muller, Pilates Mat class instructor, said FitRec started the classes to get students to try new classes without the commitment of an entire semester.

The classes were a draw for students with a cramped schedule.

“I took Pilates over the summer, and I haven’t been able to go since,” School of Education sophomore Andrea Easton said. “Pilates classes didn’t fit into my schedule, so I took ballet instead.”

Easton brought her friend, Rachel Terino, to a Pilates class to try it out.

“It was interesting,” Terino, a College of Arts and Sciences junior, said. “It was a good class. I’m just not very flexible.”

The first Happy Hour, a Fat Burn class, had 19 participants. Avitabile-Muller said most of the participants in the Oct. 13 class had never taken FitRec classes before. Last Friday’s Pilates Mat class was a mix of students and faculty.

“I had never taken a Pilates class before, but I liked it a lot,” SED sophomore Lauren Scorpio said.

Scorpio is enrolled in a kickboxing class Mondays and Wednesdays at FitRec. She has also taken rock-climbing and abdominal-workout classes.

“Make sure you register early enough,” she said.

While students can sign up for Happy Hour classes at the door, registration for physical education, recreation and dance classes offered at FitRec is available when students register for academic classes. The physical education and recreation department and FitRec offer a variety of credit and non-credit classes seven days a week.