Rate of Perceived Exertion
Training sessions are aimed at developing different aspects of fitness; power, strength, cardio, endurance, etc.
Within the cardiovascular system, there are different attributes that we are seeking to develop; stroke volume, stroke power, oxygen uptake, cardiac output, arterial dilation, VO2 Max to name but a few. These are best trained at different heart rates. Consequently, it makes sense to plan our training around different heart rates.
What is probably not so obvious is the role heart rate plays when developing muscles.
Our muscles use different energy systems at different times. The different systems can be categorised as either anaerobic and aerobic. In endurance sports, the aerobic systems produce most of the energy while the anaerobic systems cut in when we demand a sudden increase in power for things like hill climbs, break-aways or sprint finishes.
The anaerobic systems can only supply power for a maximum of about 3 minutes; after that time the energy supplies are depleted and must be replenished (active recovery during a race or during training - either active or statice recovery).
The anaerobic systems cut in when the aerobic systems can no longer deliver the power demanded by the athlete since the aerobic system is operating at maximum output.
Which explains why even our muscles should be trained at different heart rates.
Training Sessions and Heart Rate
The training sessions in the guide are carefully planned around different heart rates.
The problem is that you need to know you are operating at the right heart rate if you are to follow them.
You can do this if you have a heart rate monitor, either an independent one or on your training watch. These both have their place but what we do not want you to do is run focusing on your heart rate monitor the whole time. There are more important things to think about during training.
Which is why we use the Rate of Perceived Exertion (RPE). On Each training session you will find a RPE Chart that corresponds to the one below. This gives an indication of how you should feel at any given RPE.
If you have a heart rate monitor you can use it to mentally calibrate how running at any given heart rate actually feels during your training and the RPE scale will then provide you with a fairly accurate way to train to a given heart rate.