Two new studies find that the traditional method of teaching CPR (cardiopulmonary resuscitation) - a four-hour class - is no more effective that a 30-minute class or having kids teach their parents through a DVD.

The research is important, the American Heart Association said in a statement, because the number one reason people cite for not learning CPR is the time required.

The first study, from a team at the University of Texas Southwestern Medical Center at Dallas found that a 30-minute, video-based CPR training session was as successful as a traditional four-hour class in teaching the lifesaving skills.

Even six months after the classes, the 300 participants who took the shorter session were able to perform CPR and use an automated external defibrillator (AED) as well or better than those who took the longer course. The short-course students were also more likely to call 911, as they should, and use proper ventilation technique, say the study authors in the journal Resuscitation.

The difference may lie in the fact that the shorter courses involved more hands-on learning with each participant getting their own mannequin to practice on, rather than sharing one for every six to eight people, as is common in most traditional classes.

In the second study, 35,000 seventh-graders in Denmark were given personal resuscitation mannequins and a 24-minute DVD on CPR. The students trained in CPR at school and then were encouraged to use the kit to train family and friends.

According to the report in Circulation, surveys completed by 6,947 students showed that each respondent had taught CPR to an average of 2.5 friends and relatives at home.

"One of the most important lessons from this study is that it is possible, in a relatively cheap manner, to disseminate knowledge of CPR training in a population using children as effective facilitators," Dr. Dan L. Isbye from Copenhagen University Hospital said in a statement.

Seventh graders are ideal subjects because they are old enough to teach CPR and perhaps more willing than older teenagers to teach it to family members, Isbye said.