Rebecca Mench's too-small clothing crisis led to a painful, sweaty evening kicking and punching away the calories recently.

"I went to put my Ann Taylor pants on and I couldn't hook them," said Mench, 28, of Kailua.

She called her friend, who suggested she join a kickboxing class.

This past Monday, she went to her first kickboxing aerobics class at Kapiolani Women's Center and sweated her way through an intense 50-minute non-stop workout.

"It's beneficial cardiovascularly, a stress reliever, and they learn good defense techniques," Kapi'olani instructor Lei Alexio said. "Whatever you do, whether it is kickboxing, or running or whatever, the result of the exercise makes you feel good.

"It increases your heart rate, you release endorphins, a feel-good hormone, and you feel good about yourself."

In a six-week session, Alexio tries to teach her students the basics of kickboxing aerobics, such as front and back kicks, and basic jabs. She stresses proper pivoting and good body mechanics to reduce the risk of injury.

If students stay in the program, she adds different movements, including sidekicks, jumpkicks and combination punches.

She called it a "a different kind of kickboxing class," with an emphasis on self defense.

"With my class, it is like street kickboxing," Alexio said. "I put them in the mindset like if someone is attacking them, what would you do?"

It was what Mench was looking for. She was actively involved in canoe paddling and running marathons, but when she became pregnant with her now 20-month-old son, Gabriel, she was on bed rest.

"I lost track of taking care of myself," said Mench, an office manager. "Part of the reason to come to this class is that someone else is motivating me."

Mench's friend, Michelle Wiegand, has been attending classes for about a year. She wanted to get back into shape after the birth of her daughter, Kira, now 19 months old.

Wiegand, 34, a stay-at-home mother from Kailua, always had a fascination with kickboxing.

"It's something I've always wanted to do," she said.

She likes learning the correct techniques of self defense and that it improves her muscle tone.

Julie Ann Ikeda, a sales representative from 'Aiea, started taking the class to exercise and lose weight. It also fit nicely into her schedule.

"This is a good class if you don't have time. This class will do it for you," said Ikeda, who is in her 30s. "You just feel fit; you're more energized."

Some students may feel hesitant kicking and punching each other, even with the use of gloves and padding. Alexio said by constantly talking to and encouraging them, their confidence level rises, and they become more open to the exercise.

The class, which usually has about 15 to 20 members, begins with warm-up exercises like jumping jacks, push-ups and shadow boxing. Members then pair up, and each works on different exercises, including combination punches and roundhouse kicks.

Alexio partners students on the basis of their experience level and ability. Some beginning students work on shadow boxing and basics, while others kick and punch using gloves and pads.

They also learn about pressure points, attacking and defending.

Exhausted students muster up the strength to finish with ab work and stretching.

Nadine Chun, a student-services coordinator from Kaimuki in her 40s, said the adrenaline rush from class can keep her awake at night. She has been kickboxing for about a year, and signed up "to get really fit."

She sees it benefitting other aspects of her life.

"My stamina goes up. I'm way stronger," Chun said. "I can work longer and harder with physical chores."

Dr. Jennifer Park, a 31-year-old resident physician from Hono-lulu, uses the class as a "stress reliever."

"Work is a lot of mental stress," she said, "and I need to balance it with physical challenges."

Reach Leila Wai at lwai@honoluluadvertiser.com.