Greetings,
Even people with degrees in exercise physiology can be wrong. There are times when you have to find out for yourself.
I have done four count jumping jacks in the past and to very good effect. But let me give you the details on how they were done:
Standing Position
1- Jump out into a horse stance*, arms stretched out
2- Jump Legs together arms up
3- Jump out into horse stance, arms stretched out
4- Jump legs together, arms done
Do 2 Sets of 50-100 repetitions. Can be done with a weighted vest (START LIGHT).
This should be done on matting to reduce shock to the bones and encourage maximal fiber recruitment in the legs. The matting should not be so thick so as to minimize the actions of the calves.
The benefits:
1- Improved leg strength
2- Improved leg endurance
3- Lightness of body in movement from one stance to another. You will run up stairs like they were never there.
Prerequisite: Good strong stance foundation. This is NOT for beginners.
Unlike the conventional jumping jack, the emphasis is an getting through the transitions smoothly and softly. The major bounce through movement only evolves later when your strength improves. The bounce is full physical coordination and not a slight muscular pulse.
*My horse stance was done with the thighs forming a 90 to 120 degree angle to the crotch, with the knees and feet vectoring the same outward line as the thighs.
This four count exercise is similar to some stuff found on ballet:
http://www.youtube.com/watch?v=9Wgj-wwGWxY
Enjoy,
mickey