HTH

Sheila

http://www.ivillage.com/topics/fitness/0,10707,165562,00.htm...


If you're ready to take the next step up in intensity, burn some more calories and inject some novelty into a stale routine, ***interval training*** might be just what you've been looking for.
The idea behind it is relatively simple: Take a ho-hum run-of-the-mill aerobic workout and spice it up with a tough but short period -- called, appropriately, an interval -- of challenging intensity. Then bring it back down for a "recovery period" and do it all again. This basic template can be modified for levels of fitness ranging from virtual beginner to professional athlete.

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Although the basics may be simple, the execution can be as easy or as difficult as you want to make it. To illustrate, though, we need some tangible measure of intensity. Exercise physiologists like to talk about "percentage of V02 max," which is a basic measure of how much oxygen you are using and can be estimated from your heart rate. Too complicated. For our purposes, let's use a simple scale of 1-10, with 1 being so easy it's practically like staying in bed and 10 being the hardest effort you're capable of putting out, one you couldn't possibly sustain for long.

Now let's further assume you've just begun a fitness program and have worked up to a simple, brisk 20-minute walk. Let's say that you would rate that brisk walk as a 3 on the scale of 1-10. Great. A basic interval program for you might look like this: Walk for a while at 3; now break out at 4 1/2 or 5 for a short spurt; return to 3 while you catch your breath, and, when you're ready, do it all over again.

Douglas Brooks, in his book Program Design for Personal Trainers, calls this a "spontaneous" interval, or "speed play." You're basically having fun -- deciding when to push the gas pedal and for how long, doing it kind of by instinct. It's a great way to start, and you can vary the "gas pedal" interval by time, intensity or frequency at your own pleasure. The recommended ratio of interval to recovery time is 1:3. So if you pushed the gas for 20 seconds, you'd spend a minute (3 times 20 seconds) in recovery mode before doing it again. Of course, in the very beginning, you may want to vary that and only introduce one or two intervals into the day's workout. That's fine. You get to choose how many "spontaneous intervals" you'd like to do in any given workout.



http://www.brianmac.demon.co.uk/conintrn.htm

Interval Training


Interval running enables the athlete to improve the work load by interspersing heavy bouts of fast running with recovery periods of slower jogging. The athlete runs hard over any distance up to 1k and then has a period of easy jogging. During the run lactic acid is produced and a state of oxygen debt is reached. During the interval (recovery) the heart and lungs are still stimulated as they try to pay back the debt by supplying oxygen to help break down the lactates. The stresses put upon the body cause an adaptation including capillarisation, strengthening of the heart muscles, improved oxygen uptake and improved buffers to lactates. All this leads to improved performance, in particular within the cardiovascular system.

Before undertaking interval training a few simple rules should be understood.

* Undertake a period of Continuous running before starting Interval running
* Consider the various elements of the session and ensure that they are within the scope of the athlete.
* The length of the work interval, longer gives a better effect.
* The pace should be comfortable raising the athlete's heart rate to the required % of MHR (see above).
* The number of repetitions should reflect the condition and age of the athlete.
* The rest interval should enable the athlete to jog and bring the heart rate down to near 100-110 bpm.


* Improvements can be made by altering any of the above variables, however the coach should only change one variable at a time
* All changes should be gradual in nature and take place over a period of time.
* Ensure the surface to be run on is flat and even. It is usual to do interval training on a track although it can be done on good quality grass playing fields. Roads are not a suitable surface because of the pounding effect.


Circuit training is a common method of interval training.