The most important training concept is that of training intensity. While your long runs will ensure that you get to the finish line, it’s your training intensity which will determine how quickly you get to the finish line. It’s not just how FAR you run but how FAST you run.

There are five training intensities:

1. Speed

This is where you shed your inhibitions and run FAST. We’re talking about running repetitions on the track at your mile race speed to improve leg speed and running economy as well as neuromuscular coordination. These are the fastest sessions, and require the longest recoveries between each repetition.

How far is enough?

The best track distances for this are 200m and 400m. If you don’t know your mile race pace you can run these repetitions at about 30secs/km faster than your current 10km race pace. A 40min 10km runner would do the 400m reps in about 84-85 secs which is 3min 30secs/km pace. The recovery can be a 200m jog between 200m repetitions or a slow 400m jog between 400m repetitions as it essential that you recover fully between repetitions. The number of repeats is relatively low with perhaps just 10 x 200m or 10 x 400m. 
So how fast does my heart beat?
You’re looking at between 98-100% of your maximum heart rate

There are five training intensities:

2. VO2 max

You’ve probably heard some club members boasting of their high VO2max figures. Well you can boost yours by running intervals on the track. 

Umm, what’s VO2 max?

VO2 max can be stated in a percentage and is an indication of how efficient your aerobic system is. If you have lungs like bellows to inhale and exhale vast quantities of oxygen, a strong heart, a good network of blood capillaries and a low body mass you probably have a high VO2 max.  Sounds good to have, don’t you think?
If you are one of the brave few who has raced the 5km distance, then you will know what I’m talking about – that lung-searing feeling which means you’re in the dreaded VO2max zone where only the brave dare tread!

OK, but how do I do this?

The aim of this session is not leg speed, but rather to spend as much time as possible in the VO2 max zone. It takes about 2min of hard running before your heart rate reaches this zone and it occurs at speeds corresponding to your 5km race pace. You should spend between 3 and 5min at this intensity – just about the time it takes to boil an egg. But believe me it will feel like the longest 3-5 minutes of your life!
Track distances can range from 200m and 400m intervals (high volume with short recoveries) to 1600m intervals (low volume, longer recoveries). I favour using 1000m intervals at 5km race pace with 200m slow jog recoveries.

Can I take a break?

Yup, but not too long. The recovery time between each interval is roughly about half of the time run during the interval. If you are doing 1000m intervals at 4min/km your recovery would not be longer than 2min.  A good recovery time would be to jog 200m in about 90 seconds between intervals.
But if you try fool Mother Nature and run the intervals too fast you will soon end up lying prostrate on the grass. It is stick to the times set for the session or you will crash and burn.

OK, I will do it, but how much?

You will do a higher volume of intervals than repetitions. You can eventually build up to 20 x 200m with 100m slow jog recoveries; or 20 x 400m with 200m slow jog recoveries; or 5 x 1000m.  You could start with 6 x 400m on the first session, then do 8x and then 10x. On the 1000s you could start with 3x the first, then 4x the next week and eventually 5x.  Did I mention this is tough?
So how fast does my heart beat?
You’re looking at between 95-98 of your maximum heart rate

3. Lactate threshold

Now listen carefully! This is the key to becoming the Leader of the Pack.

Is it so good?

Studies have shown that your threshold pace is the best predictor of how well you will race.  For years, we were told that fatigue when running at high intensities was due to the build-up of lactic acid. The latest thinking is that muscle fatigue at higher intensities is due to neuromuscular fatigue caused by depolarisation of the muscles resulting from a shift in the calcium/potassium balance. Fortunately, we don’t have to worry too much as to which of these is correct as they all occur at the same point. For the sake of brevity, I will simply call this your threshold. What we do know is that your threshold basically determines what speed you can maintain over the race distance.

OK, but how do I do this?

The aim of this session is not leg speed, but rather to spend as much time as possible in the VO2 max zone. It takes about 2min of hard running before your heart rate reaches this zone and it occurs at speeds corresponding to your 5km race pace. You should spend between 3 and 5min at this intensity – just about the time it takes to boil an egg. But believe me it will feel like the longest 3-5 minutes of your life!
Track distances can range from 200m and 400m intervals (high volume with short recoveries) to 1600m intervals (low volume, longer recoveries). I favour using 1000m intervals at 5km race pace with 200m slow jog recoveries.

I’m convinced, now what do I do?

This calls for tempo runs. The pace is between your 15km and 21km race pace and you may find that you already do similar sessions on your club time trial when you run comfortably hard and not flat out.
 You can do two types of tempo runs – a sustained tempo run of between 5km and 8km; or tempo intervals. Both have merit and it is worth using both versions.

The sustained run

This gives you a non-stop period in this zone and in terms of the relatively small amount of time spent running must rate as one of the most efficient sessions you can do. To achieve maximum effect, you need to do this session either on a track or a flattish road as you need to run with rhythm and keep your heart rate at about 85 to 90% of maximum heart rate effort. You could do the 5km tempo at about 15km race pace and the 8km tempo run at 21km race pace.  Your 8km tempo pace is about 6-8seconds/km slower than your 5km tempo pace.

Tempo intervals

Now we’re back on the track where a high volume of tempo intervals with short recoveries gives you more total time spent in the threshold zone. The intervals are run at the same pace as your tempo pace, but with very short recoveries. Tempo intervals can be as short as 400m or as long as 20min. You could build up to 20 x 400m with a 30sec recovery between intervals; or 8-10 X 1000m with 60secs.  These 400m intervals are run slower than those done when doing the VO2 session.

And for the brave of heart

Two tough sessions for elite runners are 2 x 20 minutes at 10km race pace with a 3-minute slow jog recovery between.
OR a tempo/VO2max/repetition combo. It is an ideal session during the last few weeks before a race.  Begin with 2 x 1600m at tempo pace with 60secs recovery; followed by 2 x 1000m at VO2max effort with 3min recovery; then 4 x 400m at repetition effort with easy 400m jog recoveries.
So how fast does my heart beat?
You’re looking at between 85-90% of your maximum heart rate 

4. Marathon Pace (aerobic runs)

Remember the principle of race specificity? If you are training for a PB marathon you need to incorporate some Marathon Pace work in your training. These aerobic runs were popularised by the great Arthur Lydiard in the 1960s, considered the father of coaching. These mid-speed sustained runs are important for all runners and are often neglected in the search for speed.

But Surely not for 42 k’s?

Nope, save that for race day! But as they are quite tiring you might do a weekly run over 12-16km in the earlier stages of your training. Once you have reached a high level of fitness with about 6 weeks to go to the race you could do two such runs over 21km. 
A handy way of doing this is to select a local half marathon in your area and then run it at Marathon Pace.
So how fast does my heart beat?
You’re looking at between 75-85% of your maximum heart rate

5. Easy/long run pace

Now this sounds easier!
 It’s a time to let your mind wonder on a stream of consciousness, or talk up a storm with your clubmates and catch up on the latest gossip.  You’re running at a pace where you can comfortably hold a conversation.  The long run has been the mainstay of running programmes for many years and with good reason.  It helps increase your VO2max, improves endurance, increases the glycogen levels in your leg muscles and builds resistance to fatigue.

And a great variation on all this

My runners will often do a progression run, which could be any distance from 8km to a 32km run for my elite runners. Basically, with this session you start slow and finish fast. This teaches you to work hard at the end when you are tiring and is a great mental boost as you start passing runners. On most such runs, I would use three paces, easy, steady and then tempo. But on occasion on a shorter run I might add a VO2 pace at the end.

How far is far?

That depends on the distance you are training for, and upon your weekly mileage. A good rule of thumb is that your long run would make up between 25-30% of your weekly mileage. So, if you are a typical club runner who does 60km a week, one would expect your long run to be no further than 20km. This would enable you to race distances up to the half marathon.  In training for a marathon your longest runs would normally be between 32-36km. But these can be done every 2 to 3 weeks, alternating with shorter runs of about 24km.

But I don’t have all day!

It’s a fact that faster runners will spend less time on the road than slower runners.  A 3-hour marathoner would do a 36km training run in about 3hrs (5min/km) while a slower runner might take 3hrs 30min to do the same run. This greatly increases the chance of the slower runner becoming injured due to the additional time on the road. For this reason, it is best to plan for a maximum of 3 hours on your long run when training for a marathon, regardless of how much distance you cover in that time.
Another time to break the 25-30% rule is when you do your ultras as training for Comrades as on such weeks the long run will make up a much higher percentage of your week’s total mileage.
So how fast does my heart beat?
You’re looking at between 65-75% of your maximum heart rate