Stress-Based Training

I've been traveling a lot this month including 10 days vacationing in the Caribbean. I'm now in Norway with some time to kill after speaking to a large group of athletes on Saturday. So I've been thinking a lot. The following is something which grew out of having a lot of uninterrupted thinking time.

Training for racing is all about adapting to stress. Pushing yourself to the limits of your abilities in a race is highly stressful. This stress comes in the form of some combination of intensity, duration and perhaps frequency. For example, the duration of a 20km cycling time trial is relatively brief, but the intensity is quite high. A 5km running race has a similar distribution of intensity and duration. Heart rate and perceived exertion are near their upper-end limits in both types of racing. In an Ironman triathlon, however, the duration is quite high while the intensity is quite low. That's another kind of stress. A cyclist competing in a stage race has a third variable with which to be concerned – frequency. This could take the form of two stages in a day or stages on consecutive days. The combination of intensity, duration and frequency is what makes events such as the Tour de France so challenging.

We can measure and quantify stress if we know duration and intensity (we’ll mostly ignore frequency for now). It’s easy for duration. Just use a stopwatch to determine how many minutes you exercised. Frequency is also simple. Count the number of races or workouts completed in a given number of days.

Intensity is more challenging. Endurance athletes are not very good when it comes to expressing how intense a race or workout was. The most basic way, the one athletes have been using for as long as there has been competition, is perceived exertion. “That was a hard race,” always means the same thing - intensity was high relative to the duration. In a similar way athletes typically use terms such as “easy” or “moderate” to describe intensity when compared with duration. But since this is al somewhat vague, ratings of perceived exertion (RPE) have been used to quantify the intensity-duration combination. The most popular systems were developed by Gunnar Borg. Here is his 10-point scale [1]:

RPE Zone - Level of Exertion
0 - NOTHING AT ALL
0.5 - VERY, VERY LIGHT
1 - VERY LIGHT
2 - FAIRLY LIGHT
3 - MODERATE
4 - SOMEWHAT HARD
5 - HARD
6
7 - VERY HARD
8
9
10 - VERY VERY HARD (MAXIMAL)

About 30 years ago the heart rate monitor was invented. By the late 1980s heart rate zones were being used to express intensity. For example, in the system I’ve been using for the last 20 years there are seven zones based on a percentage of your lactate threshold heart rate which can be found with a 30-minute time trial [2]:

HR Zone* - % Lactate Threshold
1 - less than 0.81
2 - 0.81-0.89
3 - 0.90-0.93
4 - 0.94-0.99
5 - 1.0-1.02
6 - 1.03-1.05
7 - more than 1.05
For the purpose of this discussion I've changed my normal normal zone titles for the anaerobic zones: 5a zone to "5," 5b to "6," and 5c to "7." You'll see why shortly.

For cycling, intensity may also be quantified with zones using a power meter in a way which is similar to heart rate zones. In this case the reference point is something called Functional Threshold Power (FTPw) which is very similar to lactate threshold. This also may be found with a 30-minute time trial. Then by using percentages of FTPw power zones are established that are unique to you.

Power Zone - % FTPw
1 - less than 0.56
2 - 0.56-0.75
3 - 0.76-0.90
4 - 0.91-1.05
5 - 1.06-1.20
6 - 1.21-1.50
7 - more than 1.50

Using the idea of FTP, running zones based on pace may also be determined. Only in this case “FTPa” stands for Functional Threshold Pace [4] and found by - you guessed it - a 30-minute time trial.

Pace Zone* - % FTPa
1 - greater than 1.29
2 - 1.29-1.14
3 - 1.15-1.06
4 - 1.05-1.01
5 - 1.00-0.97
6 - 0.98-0.90
7 - less than 0.90

Besides simply expressing intensity of a workout at any given time, these RPE, heart rate, power and pace intensity zones can be used to determine how long and how intense the key “breakthrough” workouts need to be to prepare you for stress of the competition. This is based on what the race will be like in terms of stress. Given some experience in racing you should be able to estimate what the stress of your race will be. For example, if you are doing a 90-minute, steady-state bike race that will be conducted entirely in zone 4 (using whichever system from above you prefer) then the stress of that race could be expressed as a "training stress score" (TSS) of 360 (90 x 4).

Now that you know the stress demand of the race the next step is to determine the key breakthrough workouts to prepare you for the race. In the early to mid-Base periods those workouts would involve low intensities, especially zone 2. So to do a 360 TSS workout in the first half of the Base period you could train for 180 minutes at zone 2 (180 x 2 = 360). This is a grea way to improve aerobic endurance.

By the late Base period you would be training with more zone 3 time so this would require 120 minutes (3 x 120 = 360). But by this stage it is wise to break the workout into intervals since this duration-intensity combination is becoming exceptionaly demanding. So if you did 165 minutes (2:45) including 5 x 20 minutes at zone 3 (300 TSS) with 4 x 5-minute recoveries in zone 1 (20 TSS), a 30-minute warm up with half in zone 1 and half in zone 2 (45 TSS), and a 15-minute cool down (15 TSS) you would again create a 360 TSS workout. Excellent muscular endurance trainng as you normaly should be doing at this time in the season.

In the Build period interval training would again be the way to go. And since we want the workouts to become increasingly like the race these intervals would be done in zone 4. A 367-TSS workout (a little over our 360 but not by much) may then look like this.

30-minute warm-up with half in z1 and half in z2 (45 TSS)
9 x 8-minute work intervals in z4 (288 TSS)
8 x 3-minute recovery intervals in z1 (24 TSS)
10-minute cool down (10 TSS)

You wouldn't want to do a workout like this too often. It's very hard. Probably no more than once every week or two would be best. This would depend on how stressful the workout must be to prepare you for the race and what your fitness is like at the time. Runners would also have to take into consideration the potential of injury from long and intense workout combinations.

This is a lot of work but it may be a way of getting you prepared for the stress of your race. You can do all of this or you can simply use WKO+ software (http://home.trainingpeaks.com/wko-desktop-software/analysis-software-for-training-files.aspx) with your power meter and/or accelerometer and GPS device. This software automatically determines a Training Stress Score (TSS) for each workout. You can also use this software to estimate the TSS of your races. This is what I do. Much simpler. And very effective.

References
1. Borg, GAV. Borg’s Rating of Perceived Exertion and Pain Scales. Champaign, IL: Human Kinetics, 1998.
2. Friel, J. The Cyclist’s Training Bible. Boulder, CO: VeloPress, 1996.
3. Allen, H. and A. Coggan. Training and Racing With a Power Meter. Boulder, CO: VeloPress, 2006.
4. Friel, J. The Triathlete’s Training Bible. Boulder, CO: VeloPress, 1998