They say that the family that plays together stays together. In the case of the Goodins, however, it could be said that the family that kicks, blocks and punches together stays together, too.

For the 'Aiea clan, karate classes are a family affair. Husband, wife and all four children practice the martial art. But it wasn't always that way. It took decades for Charles Goodin's wife, Nayna, to join in karate classes.

High school sweethearts, Charles and Nayna Goodin met at Radford High School, when Charles was already teaching karate.

Nayna handled the business side of things and went along to collect tuition. Then, in 1997, after 20 years of marriage and four children, she took her first karate class — but only the warm-up session. She immediately noticed an improvement in how she looked and felt. Her instructor — and husband — was thrilled and reassured her: "If you want toned arms, you can punch with us." Over the next year, he said, "I tricked her into more and more exercises. Now she's hooked."

With the children, there was never any question about practicing martial arts. It was part of the family routine — like dinner or movie outings.

"I would just say, 'OK kids, everybody's going to class with Daddy," said Goodin. "Starting from age 5 or 6, they would be like little ducklings tagging along. They never said 'No, I don't want to go.' "

Goodin teaches the Shorin-Ryu form of karate as well as the Yamani-Ryu form of bojutsu, which involves the use of a six-foot wooden staff.

Goodin recommends that parents hold off introducing their children to martial arts until they are at least 5 or 6 years old.

Another recommendation: Begin with judo rather than karate. Judo can teach people how to fall — and that's a practical life skill.

"Karate is ideal to begin when you're in intermediate or high school," Goodin said. "In my school, the youngest black belt is 17."

In the Islands, a wide variety of martial-arts classes is available. It is highly recommended that anyone considering studying martial arts watch an entire class before making any decisions. Each teacher takes a different approach, and it's important to find a good match.

How does the teacher treat the students? Is it a warm, encouraging environment or is it highly competitive? Is the focus on entering and winning tournaments or on personal growth?

Goodin describes the Shorin-Ryu form of karate as "closer to tai chi than the linear and forceful forms of karate most people are accustomed to seeing." It is particularly appropriate for people as they age. "In Shorin-Ryu, there is a saying that students of the art should live to at least the age of 85. We take this very seriously," Goodin said.

ABOUT THAT BOWLING PIN

Goodin is always looking for new ways to strengthen his muscles and hone his skills. His latest cross-training device was used decades ago by martial-arts instructors: bowling pins. They serve as light hand weights that you can swing as you move. The neck of the pin is the same size as the average person's wrist, so it provides good feedback for wrist locks.

The power in karate, however, is generated from the core, not from the limbs.

"The center of the body is like a giant spring which, when wound up, allows you to explode with energy," Goodin said. "Energy originates in your core. It's a physical force, almost as if you were to pull back a string on a bow and arrow."

Over the years Goodin has investigated many forms of movement to determine which would be the best cross-training exercise for karate.

His conclusion: ballroom dancing. "It's ideal because it involves movement and grace. Dancers do well with karate because the movements are similar, and in both, you move as if there is no effort."

As Goodin's eldest son, Christopher, prepares to get married, graduate from the University of Hawai'i Richardson School of Law and launch a new phase of life, his father's advice is: "A little exercise done regularly is far better that a lot of exercise done from time to time."

Reach Paula Rath at prath@honoluluadvertiser.com.