The easiest method for measuring intensity is to simply ask the athlete to rate the intensity of the training session using everyday language, such as easy, hard, extremely hard, etc. The scale was called the rating of perceived exertion, or RPE. And there are many RPE versions available, depending on your sport. This is an example of an RPE chart designed for endurance runners. And it's fairly easy for most coaches and athletes to use. You simply ask the athlete to point the best description of their breathing during the training session and then record the score matching this breathing description. For example, if the athlete could talk in broken sentences the RPE for that training session is a 3. RPE is a useful tool to use, and is fairly reliable. You can easily design your own RPE scale. But always use the same one consistently if you do this. So here's a question. You notice an athlete is not talking. Other athletes training with her, though, are talking in broken sentences. Would you suspect that the RPE for the athlete not talking would be a 3, a 4 or a 6? Well, if you said 6 you are correct. Now you have to decide if this workout is too stressful for this athlete. Velocity is a measure of how fast the athlete is moving. Runners refer to velocity as pace. It's measured in minutes per kilometer or minutes per mile. Swimmers use time per 100 meters. Cyclists use kilometers per hour. A velocity is a suitable measure of intensity if there are no hills, no wind or in the case of swimming, if the water is calm. Varying conditions though in their environment can make it difficult to compare intensity from one training session to the next. For an endurance runner, a windy day results in a more intense training session than a calm day does. Now power is the amount of work performed per unit time. Expressing exercise intensity in terms of watts or power is relatively new, but for some sports, it has become an important indicator of intensity. Cycling and rowing are two endurance sports, in which power is used to assess intensity. It's a very reasonably accurate way to reflect intensity. Because environmental factors are minimized. Now the downside is that it relies on expensive technology. The least expensive power meter for a bike for example is 10 times more expensive than a basic heart rate monitor. Now blood lactate is a measure of acidity levels of the cells in blood, and we'll talk a bit more about this later on in the course. This measure of intensity also provides an assessment of the strength of the energy systems which is why it has been used by coaches. Until recently, lactate measurement required drawing blood and this was the downfall of this technique. However, new optical technology with LEDs embedded in a sleeve that is fitted over the calf can track lactate and muscle oxygenation without drawing blood. And this provides athletes with remarkable insight into how much effort they're expending over time. Monitoring the heart rate gauges intensity of the workout because how fast the heart is beating reflects the body's response to the energy demands of the workout. Heart rate indicates the level of oxygen and nutrients demanded by the muscles for energy. The heart must beat faster to meet a higher demand. And for this reason, there is a very close correlation between intensity and heart rate. You can use heart rate to determine recovery time. For example, if you know the athlete's resting heart rate, and the training session consists of repeated bouts of exercise, you can gauge the start of the next bout based on how close the athlete's heart rate is to resting levels.
