The racing season is coming up quickly (of course MUDS). Hopefully you are well under way with building your aerobic base. Many of you have started into speed work in the last week or two. This will be the time when you fine-tune the fitness gained in your aerobic training. Speed work has three variables: when to start, volume in each session and frequency of workouts. Let's look at each of these in a way that will help you maximize the benefits you gain from this high-end work.
A well-timed speed block will allow enough time for you to work your fast-twitch muscles and the associated energy systems. The starting point of interval work can be determined by two things: the date of your first race and your age.
A well-designed base period enables you to take good nutrition, speed work, rest, and positive thoughts and transform them into your best race possible. The choice is yours. You can either try to race with an engine the size of a lawnmower or you can build your engine up with a good base so that you are racing with a huge-turbo charged jet engine.
So figure out how many weeks of speed you can absorb and count back from your first goal race. This will give you the start date for interval work.
If you are not sure, try this test. First make sure you have a good idea of your aerobic pace at your maximum aerobic heart rate. Now go out and do between 15-20 minutes of fast running either in the form of interval work (such as 3 x 1000 on the track or 1 x 5 minutes, 2 x 3 minutes, 3 x 1 minute fartlek). Now monitor your body for the next few days. If your aerobic pace gets quicker from this workout, you will probably benefit from doing speedwork. If you get slower or get sick, your body is not in the shape to handle speed work at this time and you may benefit from doing a couple more weeks of base work.
Volume in a speed session
Now, for the second part of the speed equation: How much is going to be enough but not too much? In a nutshell, each speed-work session should have about 15-25 minutes of high-end work. The duration of each interval is not as important as the overall time you do high-heart-rate work. So you could do 8 x 400 on the track or a 10-mile time trial on the bike. Just try to do it at as high a heart rate as you can sustain and build on throughout the entire speed session. Doing 30-45 minutes of actual interval work will force you to perform at a lower speed than if you do 15-25 minutes. This will result in a diminished anaerobic and muscular benefit and will increase your risk of injury. Instead, save longer high-end efforts for the races.
Note however, that doing only five to 10 minutes of work intervals is not enough time for the body to adapt to the rigours of speed work.
A general rule is to hold the number of days of speed work in your program to two a week. Thus, if you do one speed session in each sport in a week, you will need to double up on one of the two speed-work days. The most common way to do this is to do bike speed on one day and then run and swim speed sessions on another (if you're training for triathlon). However, feel free to mix this up occasionally.
An anaerobic speed session takes two to three days to recover from. This is why you want to have a maximum of two days per week where you are doing anaerobic work -- more than this can cause your aerobic base to be sapped away -- and you risk injury and burn out.
Consider the goal of speed sessions. In essence, you want to improve your race pace and increase the amount of time that your body is able to maintain a certain level of effort. Thus, at least some of your speed sessions should include work intervals at faster than race pace.
Another adaptation that occurs when you do speed work is your body releases hormones that build new muscle tissue; however, too many weeks in a row of speed and your body will start to waste away. So keep an eye on your aerobic pace. If you see that your aerobic pace is slowing significantly (over 20 seconds per mile) this is a sign that you are at the point where it would be better to cut out speed work for a couple of weeks and do just aerobic training.
When you begin a speed session, consider the following approach. Start your first interval at a pace that will get your heart rate up to or just slightly over your maximum aerobic heart rate. On each interval after that, progress your heart rate up so that by the last repeat you are going at maximum speed and at the highest heart rate of the set. Also be sure that you descend the set, with your first interval the slowest and your last the fastest. However, if you approach the end of the set and start to lose good running form, then slow it down just a notch -- you are at the fastest pace you can go and still absorb the benefit of the workout.
As you descend speed and effort throughout a speed set, also descend the rest. Begin with a rest interval that is 50 percent of the "on" part. For example, if you run the first of a set of 400s in 90 seconds, your rest should consist of a 45-second slow jog, or, alternatively, half the distance of the work interval -- in this case, 200 meters. As you progress through the set, decrease the rest by five seconds each after each interval. This teaches you to recover at a high heart rate. As you get closer to your race, do the opposite: increase your rest throughout the set. This will help you build the high-end speed and allow you to do the anaerobic work without totally taxing your body.