This section deals with …

• What is your Lactate Threshold?
• Calculating your LT Pace
• Workouts to improve your Lactate Threshold
• Tempo runs
• Change of pace tempo runs
• LT intervals
• LT hills
• For the scientifically minded

What is your Lactate Threshold?

Lactate is produced in the muscles during carbohydrate metabolism and is used by the muscles as a fuel. When you walk or run slowly, your lactate levels remain low and relatively constant as the rate of production is equal to the rate of use. As you begin to run faster, you will reach an effort where the rate of production is greater than the rate of use, causing the lactate concentration to rise in your muscles and blood. This is your lactate threshold (LT) pace – the exercise intensity above which lactate clearance can no longer keep up with lactate production. It is difficult to run faster than your LT pace for long. However, with appropriate training you can increase the rate of lactate clearance through adaptations within the muscle fibres. Trained muscle can withstand higher levels of intensity before blood lactate accumulation occurs and your body can clear the lactate at a faster rate. So, if you can raise your lactate threshold you can run faster for longer.

LT pace is the single best predictor of race pace for 8k through to half marathon. And research has shown that improving one’s LT speed can have a big impact on marathon performance, too. Marathon runners tend to run at a speed a little slower than their LT pace.

Calculating your LT pace

It is often cited that the fastest speed that you can run while keeping lactate levels steady is a speed that you can maintain for about 1 hour (for many this is about your 10-15k pace). It is often described as “comfortably hard”. You can also estimate your LT pace based on heart rate – LT pace generally occurs at about 80-91% of your maximum heart rate.

After warming up thoroughly, run at a pace you could keep up for 30 minutes (you could use a recent parkrun time to help with this). Start your watch and record how far you run in 30 minutes. Your LT pace is 30 minutes divided by this distance. For example, if you run 7k in 30minutes your LT pace is 4.28 min/km.

Workouts to improve your Lactate Threshold

There are various ways of improving your LT pace: tempo runs; change-of-pace tempo runs; LT intervals (cruise intervals); and LT hills.

Tempo runs

The classic workout to improve your lactate threshold is the tempo run of between 20 to 40 minutes at LT pace. These sessions are mentally tougher than LT intervals, but that can help develop the mental strength required in the marathon.

However, the current approach to tempo runs is to run these sessions between LT pace and 10 seconds per mile faster than LT pace.

For example, after an easy 10-20 minute jog, run for 20 to 30 minutes between LT pace and 10 seconds faster than LT pace, followed by a cool down jog.

Change-of-pace tempo runs

This workout involves interspersing harder efforts with running at or slightly slower than LT pace. The idea is that the faster running leads to greater lactate production and the slower pace improves the body’s ability to use that lactate as a fuel. By combining several bouts of such faster running with the slower pace, you will provide a stimulus for your muscles to adapt and more rapidly clear lactate.

As an example, after a good warm-up, run for at least 4 minutes at faster than LT pace to raise lactate levels and then subsequent fast efforts for 1 to 4 minutes. The slower steady components should be at least 4 minutes long to ensure the overall workout stays in the desired intensity range.

LT Intervals

Rather than do a continuous tempo run, you can break it up into several intervals, also called cruise intervals. These efforts are run between LT pace and 10 seconds per mile faster than LT pace, with a brief recovery each time

LT intervals – Badgers Way

We run a circular route round Badgers Way, which is 0.87 miles. You will be given a time in which you are expected to complete this circuit based on your 5k/parkrun time. You should run each of the 3 (or 4) laps comfortably hard (i.e. you should NOT be able to hold a conversation!) and attempt to finish each lap in roughly the same time. You will have approximately 3 minutes in which to recover, during which you should keep moving, both to keep warm and to speed up the removal of lactate from the blood. If your times fall off, it is because you are initially running faster than your LT pace, and you will not gain as much benefit on the second and third laps since you’ll be running below your lactate threshold.

LT Hills

A good way to increase your lactate threshold is to run long hills. Find a run with several hills, such as our” Kenyan Hills” route round Buckingham. By running hard up each hill and recovering between you will accumulate a good chunk of time running at LT intensity during your run. Alternatively, find a long hill, but one that’s not too steep, and run hard up it and jog back down and repeat several times. If you can find a hill with a run down the other side, this will help your transitions from uphill to downhill during a race as well as improving your downhill technique.

Examples of LT Hill workouts:

For the scientifically minded ….

Lactate is produced in the body all the time, even at rest – it is a natural by-product of glycolysis.

LACTIC ACID = LACTATE + HYDROGEN IONS (acid)

Glycolysis is the chemical process from which we derive our energy. Without glycolysis the muscles would stop working after only 10-15 seconds of intense activity. It is believed that it is the hydrogen ions that limit the production of energy thus making you slow down, not the lactate.

Contrary to popular belief, lactate is not a waste product and does not cause fatigue. In fact, lactate is a fuel source and likely delays fatigue. Lactate also does not cause muscle soreness (which is caused by micro damage to muscle fibres), nor does it cause leg burn (this is a protective mechanism created by the nervous system to prevent runners damaging their muscles.). If it is not used immediately as a source of energy in the muscles lactate will be transported to the liver where it is converted and stored as glycogen.

Lactate removal after exercise occurs fairly quickly and does not linger for days as many people think. Following an intense exercise bout lactate levels can be back to near normal after an hour or less – even sooner if easy aerobic exercise is done, as that speeds removal. So a recovery run the day after a long run or race is not about clearing lactate from your muscles – they are very gentle/easy runs designed to leave you prepared for your next hard workout, and allow your body to adapt appropriately.

It is worth noting that the warmer the weather, the higher your heart rate will be for any given pace. This is because more of your blood is sent to the skin to help cool you down, leaving less blood available for working muscles. So don’t do any LT training in hot weather as you’ll not be able to do them hard enough to gain any benefit.