I have been teaching a cardio/strength interval class for many years and it is one of my favorite formats! It never gets boring or stale! I teach a segment of intense cardio bursts, and we do active recovery with weights. There are so many options, but if you are new to the format I would suggest the following:
–For music, there are companies out there that sell timed interval fitness CDs/downloads. You want to choose a level that works for your class. (Ex. 3:3 would be three minutes of work to three minutes of recovery. 3:1 is another example of three minutes of work to one minute of recovery.). This type of music is not necessary, but it will help you to start. You could also use a timer, such as a Gym Boss, to help you time your intervals.
–You could search the IDEA article section for some good sample classes to help you. I have found excellent ideas for my classes here. Also, www.collagevideo.com is another good resource to find ideas on interval classes. The videos are rated for level and content.
–You need to make sure you carefully plan a class in advance. If you choose a cardio/weight interval class, make sure you exhaust your larger muscle groups first and then move to your smaller muscles. (Example would be to work chest or back and then triceps or biceps.)
In terms of an “effective” class, you would need to elaborate on that. The format is very effective for weight loss, fat loss, and gaining muscle. It’s also incredible for increasing your endurance. I have many runners in my classes and they have told me many times that it helps them.
I hope some of these ideas help you. Good luck!