Eisen's students, most of them middle-aged and older, follow him through a series of slow-motion movements akin to both martial arts and dance.
The instructor assumes his posture - one leg in front of the other, arms
bent inward, hands extended.
Stepping forward, he glides his arms through the air as if it is water. Now he is on one foot and makes a slight turn to the left, then to the right.
The exercises are done in 10-minute intervals, and in a motion so slow that they seem incapable of improving one's physical stature. But Eisen is quick to point out that there is much more involved here than simply building muscle tone.
"We're building a whole way of life," says Eisen.
The way of life is tai chi chuan, a combination of Chinese exercise and Eastern philosophy.
Commonly knows as tai chi, it focuses less on external physical development and more on strengthening one's internal organs. Based on the Taoist philosophy of yin versus yang, tai chi's emphasis is on regulating the flow of energy within one's body to keep it on an even keel.
A regulated energy flow, according to Eisen, promotes better overall health.
"It's the natural health idea," said Eisen, a Cherry Hill resident who teaches tai chi several nights a week at various locations throughout South Jersey.
"The purpose of tai chi is to cultivate harmony in mind, body and spirit," he said. "Many illnesses today are caused by stress. But if your body is in harmony through a proper energy flow, you can cut down that stress and hence prevent and cure illnesses."
Under the principles of tai chi, energy flows upward in the body (from the instep of the foot to the top of the head and down the back) through channels called meridians. If that energy is allowed to stagnate, one can become ill.
This principle was discovered by the ancient Chinese upon examination of a patient with hemorrhoids, Eisen said.
Because of its non-strenuous nature, tai chi is best suited for middle-aged people and senior citizens, said Eisen. His subjects, who pay $20 a month to participate in his group, say they are satisfied customers.
"I've been able to call upon my lessons learned in tai chi class to relax myself on the job," said Abner Hines, 60, a superintendent of vehicle operations for the U.S. Postal Service. "I'll just walk off in a corner, or another room, and rid myself of the stress that builds up during the course of the day."
"I've been able to recognize the stress and deal with it," said Jim Favala, 43, of Cherry Hill. "The other day I was driving in traffic and I got a headache. I did some tai chi breathing exercises and got rid of it."
Favala, an attendance officer for the Camden school district, said tai chi also has helped him be more relaxed on the job. "It's a job where you can blow your stack fairly easily," he said.
Eisen, a soft-spoken, smallish man with a slight paunch, is a professor of mathematics at Temple University. The Cherry Hill resident has studied martial arts for more than 25 years. He also teaches judo and praying mantis kung fu, another Chinese exercise similar to tai chi that utilizes more rapid movements. He also is an avid jogger.
Eisen warns that one should never attempt to break a brick with a tai chi stroke. But despite its docile characteristics, tai chi can be used as a self- defense skill. Instead of using strength against strength, however, the key factor in tai chi is neutralizing the opponent's force and turning it against him.
"You make your body flow like water," Eisen said. "It's again the concept of yin and yang. If he yins, you yang. You never resist his force - you flow with it until your opponent loses his balance. It's like bobbing and weaving in boxing.
"Of course, as the battle rages, you'll eventually have to increase the speed of your movements. Unless the guy is on drugs, you're not going to lull him into a tai chi pace."