THE PARAMETERS FOR TRAINING RUNNING: POWER

Systems to detect and measure power have been in running one of the most interesting innovations in recent years. These instruments are capable of measuring not only the watts delivered but also other interesting values such as time of flight, vertical oscillation, and ground contact time. All important data that you can use to improve performance and energy cost of your run. With the use of running power you make a quantum leap because you have a truly objective parameter. If already pace versus heart rate allows you to manage more stable and comparable values, power can also isolate the effects on running of different surfaces, changes in slope and some atmospheric factors such as wind.

Two types of sensors

Power sensors for running have only appeared on the market in recent years. There are two types of instruments: direct power meters and meters that use an indirect method. The direct instrument takes all measurements directly from the sole of your foot. An example of a commercial product is the FeetMe: an insole to be inserted inside the running shoe that has a series of sensors that can measure the pressure the feet exert on it but also the acceleration in space. This instrument can measure all of the values listed above but was found to be sensitive to the type of shoe you are using and the type of surface you are running on.

Indirect systems, on the other hand, are devices that through the measurement of acceleration and cadence are able to obtain the data you need, by virtue of your body mass. These systems are embedded inside foot pods, wristwatches or in the sensors of heart rate bands. Among these systems, the Stryd foot pod is certainly the best known and most widely used.

The interesting aspect of watt meters for running is the ability to work on improving your efficiency. The energy cost of running can be defined as the amount of energy you use to sustain a certain gait. This is an important concept because your performance is a function of your displacement (VO2 MAX), the fraction of it that you are able to use during competition and just the energy cost of your run. You should devote more attention to it because, like any runner, you are willing to devote hours a week to improving your conditional skills but struggle to carve out a few minutes for running technique exercises that could move you forward both in terms of performance and reduced risk of injury.

Efficiency with the power meter you can measure it by comparing the watts you need to sustain a certain running pace. By improving your technique and lowering your energy cost you will need fewer watts to keep the same gait. At the same time at the same watts you will go faster which is definitely the thing you are most interested in. It has been repeatedly shown that in high-level competitions, energy cost is the variable that determines the winners of distance competitions.

Discover your areas of intensity…

Even if we change the benchmark between heart rate, pace and power at the base of our training there must always be a test. Only by knowing your correct intensity zones can you best manage your workouts. For tests to be used, one can take a cue from those used in cycling where power measured in watts is now commonplace among advanced cyclists and triathletes. If for a cyclist the 20-minute test gives an excellent estimate of your intensity zones, so in running a 5-kilometer test can give you the same reliability. The duration of a 5-kilometer test can range from 18 minutes for a good amateur to about 30 minutes for those who still struggle to stay under 60 minutes in the 10 km. This duration allows us to make a good estimate of threshold power first and then all other intensity zones. To do this put on your watt meter and run 5 km to the best of your ability. To know the estimated value of your threshold power in running, you need to multiply the average watt value maintained in the test by 0.95. If the value obtained in the test is 320 watts then your rFTP (running functional threshold power) will equal 304 watts (320 x 0.95). For less trained and inexperienced amateurs over distances longer than 5 km, the coefficient for calculating rFTP can be reduced to 0.92 so as not to risk overestimating all intensity zones.

…and make the most of them!

As with heart rate and pace, different patterns of intensity zones can be used. Those applied for cycling are not always ideal especially with regard to zone 1. In running even at low speeds, the minimum wattage required is significantly higher than that needed for pedaling on the flat at low speeds. Zone 1, which in cycling reaches up to 55% of ftp in running, is impractical. At 55% rFTP you practically walk. Moreover, wanting to compare the two values for those who play both sports, it appears that the threshold value in running is usually higher than in cycling. The need on the one hand to lift the entire body mass off the ground with each step and the use of more muscles are the main causes of this difference.

Once you have estimated your training zones you can start training using watts.

What are the workouts in which it is appropriate to use power?

If we had already seen about how pace versus heart rate is a more objective parameter, with the use of power you have an even more accurate tool. You can use watts for all kinds of exercise: from short sprints to long runs. You can compare the watts delivered at different times to see how your running economy changes. In the face of technical and mechanical improvement at the same speed the watts required must decrease.

In training sessions or races where differences in road surface, slope or weather situation can be crucial, watts are best. Hilly running is the situation where running based on watts gives you the most accurate result. If you decide to contain your effort in zone 3 you can set a specific target of watts not to exceed. This works in both a 2% climb and a 10% ramp. On varying slopes establishing a target pitch is meaningless because the determining variable is the slope of the climb, not the speed. Another situation where you can dose the effort better with the watt meter is a very windy environment. Running against the wind increases the effective effort exponentially. If you persist in keeping a pace you can very quickly exhaust all your energy. If you keep within a controlled power target, however, you can run more smoothly and make up for lost minutes in subsequent windward stretches.

Power gives you a new opportunity to manage intensities even better during your run and goes to bridge the limits that heart rate and pace have in certain situations.

main image credit: TarasMalyarevich on DepositPhotos.com