The road to success

Dr Jason Karp suggests some sessions for improving at both the 10km and the marathon

Posted on October 20, 2011 by
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distance runners (Mark Shearman)

Two of the more common long road race distances are the 10km and marathon and in this article we will look at the training implications and what is needed to make sure you get your best performance.

10km training

Whether you are training for 10km or a marathon, it all starts with mileage, because endurance training stimulates many physiological, biochemical, and molecular adaptations.

For example, endurance training stimulates more fuel (glycogen) to be stored in your muscles, increases the use of intramuscular fat at the same speed to spare glycogen and increases the size of the left ventricle of your heart so that it can pump more blood (and oxygen) with each beat.

It also improves your blood vessels’ oxygen-carrying capability by increasing the number of red blood cells and haemoglobin, creates a greater capillary network for a more rapid diffusion of oxygen into the muscles and, through the complex activation of gene expression, increases the number of mitochondria.

Lactate threshold (LT) runs

You can improve your LT by running at your current LT pace. Increasing your LT pace allows you to run faster before you fatigue because it allows you to run faster before the anaerobic metabolism begins to play a significant role.

I typically use three types of LT workouts with my athletes: (1) continuous runs (3-8km) at LT pace; (2) intervals run at LT pace with short rest periods, such as 4-6x1600m at LT pace with one minute rest; and (3) shorter intervals run at slightly faster than LT pace with very short rest periods, such as 2 sets of 4x1000m at five to 10 seconds per mile faster than LT pace with 45 seconds rest and two minutes rest between the sets.

LT pace is about 10-15 seconds per mile slower than 5km race pace (or about 10km race pace) for runners slower than about 40 minutes for 10km (about 80-85 per cent maximum heart rate). For highly trained and elite runners, the pace is about 25-30 seconds per mile slower than 5km race pace (or about 15-20 seconds per mile slower than 10km race pace, or about 90 per cent maximum heart rate). These runs should feel comfortably hard.


Long intervals (3-5 minutes) run at the speed at which VO2max occurs (approximately 3000m race pace for highly trained runners and between 1500m and 3000m race pace for non-elite runners) increase the heart’s stroke volume and cardiac output, leading to an increase in VO2max. If using heart rate, you should come close to reaching your maximum heart rate by the end of each interval.

Marathon training

Given the length of the marathon, there are some things that limit your performance that don’t play a major role in shorter races. The main difference is that you run out of carbohydrate, which is your muscles’ preferred fuel. You have enough stored carbohydrate (glycogen) in your muscles to last slightly more than two hours of sustained running at a moderate intensity. So, unless you run a marathon as fast as Paula Radcliffe, you’re going to run out of fuel. Glycogen depletion and the accompanying low blood sugar (hypoglycaemiac) coincide with hitting the infamous wall.

Other issues not encountered in shorter races that affect marathon performance include dehydration, muscle-fibre damage, hyperthermia and psychological fatigue.

When you sweat a lot, you become dehydrated, which causes a decrease in the plasma volume of the blood, decreasing the heart’s stroke volume and cardiac output. Oxygen flow to your muscles is then compromised, and the pace slows.

The relentless pounding on the pavement also causes muscle-fibre damage, which decreases muscle force production.

Since your muscles produce heat when they contract, running for long periods of time increases body temperature and the resulting hyperthermia decreases blood flow to the active muscles since more blood is directed to the skin to increase convective cooling. Finally, running for so long can cause psychological or neural fatigue, the latter of which is due to changes in the levels of brain neurotransmitters.

High mileage

While high mileage is important for the 10km, it is especially important for the marathon to maximise your aerobic capacity. This sometimes requires running twice per day to spread out the stress and maximise recovery.

In addition, runners who run a lot tend to be more economical (they use less oxygen at a given pace). Economy is improved largely from increases to capillary and mitochondrial density, the former increasing the speed that oxygen can diffuse into your muscles, and the latter increasing your muscles’ capacity to use oxygen.

It is also possible that the countless repetitions of the movements of running results in optimised biomechanics and muscle-fibre recruitment. Additionally, economy may be improved by the weight loss that usually accompanies high mileage, which leads to a lower oxygen cost; the enlargement of slow-twitch skeletal muscle fibres, which are more suited for aerobic metabolism; and a greater ability for tendons to store and utilise elastic energy with each step.

Long runs

The main difference between 10km training and marathon training is the inclusion of much longer runs. Since your body has a much better concept of time than of distance, the amount of time spent on your feet is more important than the number of kilometres you cover. Repeatedly running for long periods of time (longer than two hours) presents a threat to the muscles’ survival by depleting their store of glycogen. However, the human body responds rather elegantly to situations that threaten or deplete its supply of fuel. When muscle glycogen is depleted by running long, your body responds by synthesising and storing more than what was previously present, thus increasing endurance for future efforts. The more glycogen you have packed into your muscles, the greater your ability to hold your marathon pace to the finish.

If you’re planning on running a road marathon, do all of your long runs on pavement to prepare for the muscle-fibre and connective-tissue damage you’ll sustain in the race.

While you should try to not let your long run comprise more than about 30 per cent of your weekly mileage, this rule can be broken in the name of necessity if you plan on running only a few times per week. Run at a comfortable, conversational pace (about two minutes per mile slower than 5km race pace, or about 70-75 per cent of maximum heart rate).

Lengthen your long run by two kilometres each week for three or four weeks before backing off for a recovery week. Keep adding kilometres until you reach 35-38 (or about 3-3½ hours, whichever comes first), and do your longest run two to three weeks before your marathon.

My study on the training characteristics of the 2004 US Olympic Marathon Trials qualifiers, published in International Journal of Sports Physiology and Performance in 2007, found that the men’s and women’s longest runs averaged 40 and 38 kilometres respectively, and they ran longer than 32 kilometres an average of 18 and 10 times, respectively, during the year leading up to the Olympic Trials.

LT runs

LT runs are very important to prepare for the marathon just as they are for the 10km. The longer the race you’re training for, the more important it is to train your LT because the closer the race pace will be to your LT pace and the more important it becomes to hold a hard pace for an extended time.

To this end, you need to extend the duration of your LT runs when training for a marathon. To accommodate the increased duration, you can run a bit slower than LT pace. Since optimal marathon pace is only about 15-20 seconds per mile slower than LT pace (with the difference in paces getting larger as performance level declines), the goal of marathon training is to raise your LT and to increase your ability to sustain as high of a percentage of your LT as possible.

If you’re experienced with doing many long runs, try including LT-paced running into some medium-long runs (19-25 kilometres). These LT/LSD combo runs let you simulate the physiological and psychological fatigue of the marathon without having to run as far. Like long runs, they severely lower muscle glycogen, stimulating its synthesis and storage.

You can include LT segments at the beginning, middle, and/or end of the run. Some examples are: (1) 6km at LT pace + 12km easy; (2) 8km easy + 5km at LT pace + 8km easy + 5km at LT pace; and (3) 16 kilometres easy + 6 kilometres at LT pace.

After you’ve done a number of these combo runs, try running faster than LT pace for the last two kilometres of the final LT segment, which will get you sharp for the marathon. For example, run 14km easy + 6km at LT pace + 2km faster than LT pace. You may want to run the LT segments on a track, where you can closely monitor your pace.

Because these workouts are very tough, alternate the long run with the LT/LSD combo run every other week, and after three or four weeks, don’t do either run for one recovery week.

The next time you train for a 10km or marathon, follow these training guidelines. And if you train smart enough, not only will you increase your fitness, you may even be able to chase Pheidippides.

» Dr Jason Karp PhD is a speaker, writer, author and exercise physiologist. See more at

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