Training intensity varies from workout to workout, depends on the athlete’s goals and available measuring devices, the training cycle they are in, and most of all are always assigned with purpose.
Why vary intensity?
The goal of the workout is to bring positive physical changes in the body to deal with the physical stress on race day. The most efficient method to bring about these physical changes is to put your body under training stress. Changing the pace, duration, frequency or intensity of the workout are all means to manipulate the training stresses. The formula is simple: different intensities lead to different types of stresses for a well-rounded athlete.
I have been focusing on short distance racing so far this year and with that have been playing around with different intensity measures myself. The most significant difference is looking at input (how hard it feels) versus output (performance). Nobody better than I know that ‘how hard it feels’ can be very different from what my performance proves. Just the other day I was out running, and it felt incredibly hard. Meanwhile, I was trudging along in heart rate zone 1 at a turtle pace.
It makes a difference whether I use, e.g., heart rate or pace and I can feel the various training effects. If I intend to work on my endurance, I am better off focusing on my heart rate. If my goal, however, is a particular time, I need to make sure I hit the right training and racing paces. So, how about a short review of what one does over the other?
There are several practical and easy ways to measure the intensity of exercise. The basic ‘input’ metrics are Rate of Perceived Exertion (RPE) and heart rate. ‘Output’ tracks metrics like pace, speed, and power.
Rate of perceived exertion (RPE)
With RPE, the person assigns an intensity score, typically 1-10 with ten being the hardest, according to how they feel. It ranges from “I’m watching TV while eating my chocolate” and goes via labored breathing (“I can still talk, but don’t really want to”) to the conversation being nearly impossible (“I can squeak in response to your questions”) to one-word responses (“Dead”). I find that elite and pro athletes are always fantastic at this and at how tuned in to their bodies they are whereas the average age group athlete is probably better off trusting the numbers assigned whether that be heart rate, pace, or power.
The biggest problem with heart rate is that it is tremendously affected by outside force. Did you have too much coffee this morning? How hot or cold is it? Is there a lot of wind or elevation changes? Did I get in a fight with my spouse before heading out the door or do I have other life stress going on? Was my nutrition on point for this workout? The list goes on. Heart rate is also only responsive, as in, it responds to what the rest of my body is doing, therefore lagging behind and not providing me instant feedback to increased or decreased efforts.
However, it also can tell me a lot about your state of endurance and your efficiency. Via your GPS enabled heart rate monitor, TrainingPeaks calculates your efficiency, and I can track and compare trends over time and know whether you are improving or not. In turn, that dictates upcoming training sessions.
Pace and speed
I think this one may be self-explanatory. The one who rides or runs the fastest wins the race. Pacing, to me, is essential as a training parameter, especially when you want to qualify for Boston or Kona, or have a goal time for any given race. But, it can be detrimental when used in a race as a single metric. Hills, wind and road surface hugely impact pace and speed.
Power meters have been used in cycle training for years and shown significant improvements for athletes. This concept is also being applied to run training. I have seen fantastic results training athletes with a power meter (both running and cycling), and it certainly speaks to me as the data geek that I am. With a power meter, you now have a pro-active tool that gives you immediate feedback on what your muscles are doing. But, I don’t have to repeat here why a power meter is so awesome. You can review my other article on that subject.
Working out with a purpose
In the end, all metrics combined in one form or another will bring about progressive changes. As I always like to say, by the time you hire a coach, you are no longer ‘just’ working out. You are working out with a purpose. You want to improve your performance. When I put together your training, I make sure to assign intensities that match the requirements of your goals.