Alternative Methods for Determining Intensity
By Rich Strauss

In my article Training Zones Explained, I introduced the method of using heart rate to determine training intensity. Next I will introduce two alternative methods of determining training intensity.

Think of your heart rate as a window. During a workout, you peer through this window and catch a glimpse of everything that your body is doing at the time. In our training, we want to look through clean glass and get a clear picture of exactly how hard we are actually working. But our window is sometimes "dirty." The following is a list of the dirt that is sometimes on our window:

• Lack of Hydration
• Poor Nutrition
• Incomplete Recovery
• A State of Over-Training
• Temperature

I will explain how this dirt effects our ability to see through the window. Let's take hydration and temperature for our example. When we get hot, we sweat. This sweat evaporates and removes heat from the skin through evaporative cooling. At the same time, in order to quickly remove heat from the body's core, blood flow to the capillaries of the skin is increased. This action takes the warm blood from the core and exposes it to the sweating and evaporative cooling effects on the surface of the skin. High temperature combined with poor hydration has the following effects:

• Water must be taken out of your blood to provide sweat for evaporative cooling.
• This thickens the blood, making it more difficult to pump.
• Your heart must now work harder to pump this thick blood to where it is needed: muscles for producing work, and skin to provide cooling.

What you see is a sudden increase in heart rate without in increase in intensity or pace. For example, your workout schedule calls for a 3 hour bike followed by a 1 hour run. During your ride you lose a bottle, it's a hot day, and you get behind on your hydration schedule. You start the run at your required pace, but your heart rate for some reason is abnormally high and you can not get it down into your prescribed training zone. You are dehydrated.

You look through your window to determine training intensity and instead of seeing a clear picture of exactly how hard you are training, your vision is clouded by the effects of temperature and hydration. For the moment, let's put aside the dangers of training in a dehydrated state. If in this example you only used your heart rate to determine your training intensity for this run, you would slow your pace and would not be running fast enough. Poor recovery, nutrition, and over training all have the same effects as our example above.

Heart rate, when used alone, can often prevent us from training at the proper intensity. In my next articles I will introduce two alternative methods of determining training intensity: Critical Speed and Critical Power.