As with any exercise regimen, progression with interval training
workouts is the key to improvement. I would recommend an aerobic
capacity of 30 minutes steady output at 75-80% before adding interval
training to your routine.

So where do you start? The type of exercise is up to you. Run or bike or
run stairs outside, treadmill, spin bike, or stairmaster at the gym. It
is the work/rest ratio that you will manipulate.

Start with a work/rest ratio of 1/4. An example would be 10 seconds
on/40 seconds off. Move to 1/3, then 1/2, and finally 1/1. Within the
changing ratios you can extend the work and rest interval. The 1/4 ratio
can be 30 seconds on, 2 minutes off. Staying within that time frame,
eventually you would have a workout that was 30 seconds on, 30 seconds
off.

How many intervals? Begin with 5 or 6 in whatever ratio you feel is
best. Work up to 10-15 at any prescribed ratio. 30 minutes total time
would be a great workout.

Remember, the work interval is all out, the rest interval is about 50%
of the work interval.

Steve K.