Do interval training starting with one time a week since it is intense. The idea to interval training is to set up work to active recovery ratios (work:active recovery), and as you get more fit, you decrease the rest time and increase the work time. A general example (which may not apply to you but which you could modify to your own pace without risk of injury, for example, walking, not running) is the following:
If you currently run for 30 minutes at 6mph, try jogging for 5 minutes to warm up, then increase the speed to say 6.5mph and jog for 1-2 minutes (less time if you can't go that long), then jog again for a few minutes at your normal speed, then run again at the faster speed, and so on until you reach your time limit. The work:active recovery ratios would be 2:3 if you ran for 2 minutes at 6.5mph and jogged for 3 minutes at 6mph. Over the course of the next few months you will get more fit if you continue with this type of training.
You can also get more specific and use heart rate. Your heart rate is an excellent indication of how hard you are working. For example, if your heart rate is at 70% of your predicted max when you jog at 6mph, then start at that speed and then either increase the speed or elevation, and increase it so that your heart rate increases to 85% or even 90% for 1-3 minutes to start, then back to your jogging speed at a heart rate of 70%. That's a starting recommendation. Over time, your conditioning will improve and then your heart rate will be lower at the higher speeds and you can spend more time at the work speeds and less during the active rest period. You can always vary the ratios if they turn out to be too hard or too easy. 1:3 is a good starting ratio.
Or you can use a bike or elliptical and do the same thing.View Thread
Circuit training is where you spend 30-45 seconds at one weightlifting machine or resistance exercise (like crunches or dumbbells) and then move quickly to the next. It's what they do at Curves. It's a great aerobic and resistance exercise in one and you can do it without stressing your knees. If you belong to a gym a trainer can design a circuit program for you.View Thread