Interval Training for Cyclists
Why do intervals?
The basic concept behind interval training is to increase the overall amount of time spent training at a high intensity and therefore increasing your endurance performance or ability to ride faster for longer. It is known that training at a high intensity leads to perfomrance gains, particularly amongst trained individuals. The whole point of intervals is to allow you to increase the amount of time your body is able to train at a high intensity therefore increasing your fitness levels.
This increased high intensity training time is achieved by performing intervals of high intensity work, separated by periods of low intensity or recovery riding. Lets look at an example: if you were to cycle at 95% of your maximum heart rate you may only be able to sustain that level of intensity for say 20 minutes before exhaustion set in. However if you were to perform intervals at the same intensity (90% of max) of 10 minutes each, with 15 minutes of recovery in between (at 65% of max), you would most likely be able to perform 3 intervals. By performing the intervals you will have performed 30 minutes of high intensity work instead of just 20 minutes and should therefore improve your fitness at a greater rate.
Intensity is key
The key to successful intervals is intensity. They are particularly unpleasant to perform as they require you to train at a high intensity however the benefits they bring in terms of increased fitness are usually worth it. To get the most from them ensure that the intensity is high and you allow enough time to recover at a low intensity in between intervals.
Although intervals can be performed using you judgement or "perceived effort" using a heart rate monitor or power meter enables you to see exactly how hard you are working. It is worth noting however that if your intervals periods are very short (say 30 seconds or 1 minute) you heart rate will take time to settle down and reduce during the recovery phase. As a result during very short intervals it is probably better to use perceived effort as your measure.
Types of interval training
To releive boredom and also improve your riding over a range of disciplines it is best to mix up the types of intervals you perform. Below are a few example interval workouts you may consider integrating into your training.
Lactate Threshold Intervals
As discussed elsewhere is the same as your time trial pace. You can find out your lactate threshod is by performing a lactate test. The purpose then of lactate intervals is to increase you lactate threshold which will have the affect of allowing you to ride further at a higher intensity.
The classic lactate interval would consist of 2 x 20 minute intervals at 85% of you maximum heart rate (MHR). The remainder time (10 minutes to warm up, 10 minutes recovery in between and 10 minutes cool down) should be performed at 65% MHR. You may want to adjust the 85% figure slightly. The aim is to be working at such an intensity that you can just about maintain a consistent pace thoughout both intervals but another few minutes on the end of the second interval would cause you to blow up. If you are forced to slow down during the second interval you have gone out too fast in the first one. It may take you a few tries before you get he pace right so experiment to find out the exact level of intensity that works for you.
Sprint Intervals
Here the focus is on more higher intensity all out intervals that are performed for a much shorter period of time. A typical workout may consist of 8 30 second sprints where you go as fast and as hard as you can. Leave about 5 minutes in between each interval and reduce your heart rate to around 65% MHR. Remember to warm up and cool down for 20 minutes (again at 65% MHR) before and after the intervals.
Hill Intervals
If you have a rolling course or route available to you then you have a ready made hill interval workout. Treat each hill as an interval where you raise your heart rate up to about 85% MHR or just above. Use the flats and downhills to recovery and get your heart rate back down to 65% MHR.
Recovering form intervals
Due to the overall increase workload you'll be placing on your body by performing interval workouts it is crucial that you allow your body adequate recovery time. You should try to avoid performing more than two interval workouts per week and try to ensure you have scheduled a light training day before and after each interval session to allow your body to recover from the extra workload.