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Marathon Training 101

by Jason Karp, PhD on May 27, 2009

Ex Rx

Understanding the key components of long-distance training for runners will help your clients excel in their next marathon.

In 490 BC the ancient Greek hero Pheidippides ran from Marathon to Athens to announce the Greeks’ victory over Persia in the Battle of Marathon. When the modern Olympic Games began in Athens in 1896, a running race named after the Greek town of Marathon was introduced to commemorate Pheidippides’ legendary run. Now there are more than 300 marathons just in the United States each year, with hundreds of thousands of people running them. Chances are that one or two of your clients want to do one. So how do you train them for a marathon?


The number of miles your clients run each week is the most important part of their marathon training. To run 26.2 miles (42.2 kilometers), your clients need to become as aerobically developed as possible. Running lots of miles helps with this in many ways:

  • It improves blood vessels’ oxygen-carrying capability by increasing the number of red blood cells and the amount of hemoglobin.
  • It stimulates the storage of more fuel (glycogen) in the muscles.
  • It increases the use of intramuscular fat to spare glycogen.
  • It creates a greater capillary network, allowing for a more rapid diffusion of oxygen into the muscles.
  • It increases mitochondrial density and the number of aerobic enzymes (through the complex activation of gene expression), thereby increasing aerobic metabolic capacity.
Long Runs

The ability to perform prolonged endurance exercise is strongly influenced by the amount of glycogen stored in skeletal muscles (Ahlborg et al. 1967), with fatigue coinciding with glycogen depletion (Sahlin, Tonkonogi & Söderlund 1998). Glycogen depletion and the accompanying low blood sugar (hypoglycemia) coincide with hitting the infamous marathon “wall.” Therefore, the marathon requires the largest glycogen storage capacity possible, a very efficient capacity to make new glucose and a very effective use of fat.

Long runs present a threat to the muscles’ survival by depleting their store of glycogen. Depleting muscle glycogen forces muscles to rely on fat as fuel. The human body responds rather elegantly to situations that threaten or deplete its supply of fuel, synthesizing and storing more than what was previously present, thus increasing endurance for future efforts. Empty a full glass, and you get a refilled larger glass in its place. The more glycogen your clients have packed into their muscles, the more able the clients will be to hold their marathon pace to the finish.

In addition to serving as a stimulus to store more glycogen and rely on fat, long runs prepare your clients’ muscles and connective tissue to handle the stress of pounding the pavement for 26 miles. For this reason, all of their long runs should be on the road (unless they’re planning to run a trail marathon). Given that prolonged exercise has been found to cause psychological or neural fatigue, the latter of which is due to changes in the levels of brain neurotransmitters that may increase the perception of effort and feelings of tiredness and lethargy (Davis & Bailey 1997), long runs also callous your clients for what they may experience in the marathon itself.

The long run shouldn’t comprise more than about a third of your clients’ weekly mileage, although this may not be possible if they run only a few times per week. They should run at a comfortable, conversational pace (about 2 minutes per mile slower than 5K race pace, or about 70%–75% of maximum heart rate). Lengthen their long run by 1 mile each week for 3 or 4 weeks before backing off for a recovery week. If your clients run more than about 40 miles per week, or if they run faster than about an 8-minute-mile pace, you can add 2 miles at a time to their long run. Keep adding miles until they reach 21–23 (or about 3–31/2 hours, whichever comes first), and have them do their longest run 2–3 weeks before the marathon. Since your clients’ legs have no concept of distance, only of intensity and duration, the amount of time your clients spend on their feet is more important than the number of miles they cover.

Lactate Threshold Runs

The lactate threshold (LT) is the fastest running speed above which lactate production begins to exceed its removal, with blood lactate concentration beginning to increase exponentially. It demarcates the transition between running that is almost purely aerobic and running that includes significant oxygen-independent (anaerobic) metabolism. (All running speeds have an anaerobic contribution, although that contribution is negligible at speeds slower than LT pace. Thus, the LT is an important determinant of marathon performance since LT represents the fastest speed your clients can sustain aerobically.)

As clients train at LT pace, their LT pace increases, and what was an anaerobic intensity for them becomes high aerobic. Since optimal marathon pace is only about 15–20 seconds per mile slower than LT pace (with the difference between the two getting larger as performance level declines), the goal of marathon training is to increase your clients’ LT pace and their ability to sustain as high of a fraction of their LT as possible (see the sidebar “Sample Marathon Training Program,” outlining the third and fourth cycles of training, which include LT workouts).

If a client is more competitive and has a running background that includes many long runs, alternate his or her long run with a medium-long run (12–16 miles)combining long, slow distance (LSD) running with segments at LT pace. These LT/LSD combo runs simulate the physiological and psychological fatigue of the marathon without the client having to run as far. Like regular long runs, they severely lower muscle glycogen, stimulating its synthesis and storage.

Long Intervals

Long intervals (3- to 5-minute periods of hard running with 2- to 4-minute recovery periods in between) that are run at the speed at which VO2max occurs provide the greatest cardiovascular load. This is because clients repeatedly reach and sustain their maximum stroke volume (the volume of blood pumped by the heart per beat), cardiac output (the volume of blood pumped by the heart per minute) and VO2max during the hard running periods. Long intervals are the most potent stimulus for improving VO2max (Billat 2001; Midgley, McNaughton & Jones 2007). The higher your clients’ VO2max is, the higher their aerobic ceiling will be.

The Taper

Progressively reducing, or tapering, the training may be the most complicated part of marathon training. You want your clients to back off on their training enough to recover completely and eliminate all fatigue, but not so much that they lose fitness. Research has shown that tapering brings about changes in biological markers that reflect a reduction in training stress and an enhanced recovery, and that performance is more likely to improve (by 0.5%–6%) after tapering (Child, Wilkinson & Fallowfield 2000; Houmard et al. 1994; Mujika & Padilla 2003; Mujika et al. 2004; Shepley et al. 1992).

To maintain fitness when tapering, the intensity of training seems to be more important than either the training volume (weekly mileage) or frequency. To taper your clients’ training, reduce their weekly mileage exponentially, include some interval training to maintain training intensity and tell them to increase their carbohydrate intake (to at least 70% of total calories) to increase the amount of glycogen stored in their muscles for race day. As clients get closer to the marathon, reduce the volume of intensity by reducing the number of intervals in each session. Although research has shown that reducing training volume by 60%–90% can improve performance, the research is limited to much shorter races that are not as endurance-dependent as the marathon. Given the length of the marathon, and thus its large dependence on aerobic capacity, it is better not to decrease mileage by as much as 90%. This is especially important for runners who are less talented or less fit (4- to 5-hour marathoners), who will be better served spending as much time as possible developing their aerobic capabilities rather than backing off for a full 3 weeks before their marathons.

The exact length of the tapers will depend on your clients’ prior training load, their level of fatigue and their genetically predetermined ability to retain training effects while reducing the training stimulus (i.e., how quickly they lose fitness). With my athletes who run high mileage (more than 70 miles per week), I typically begin cutting their mileage 3 weeks before the marathon, reducing it to 70% of peak training mileage the first week, to 50% the second week and to 35% the week of the marathon (not counting the marathon itself).

During the first week of the taper, keep the intensity high, including one long interval workout and one LT/LSD combo run. Decrease the intensity slightly during the second week, including two short- to medium-distance runs (5–10 miles) at marathon pace. The week of the race, have clients do one interval workout early in the week at either LT pace or slightly faster, cutting back on the pretaper number of reps. Also during the final week, schedule a daily reduction in mileage over the last few days, mirroring the pattern of the weekly reduction. Of course, exactly what your clients do during the taper will depend on what they did before the taper.

So the next time you have clients who want to run a marathon, follow these training guidelines. If your clients train smart enough, not only will they cross the marathon finish line basking in the glow of their accomplishments; they may even be able to chase Pheidippides.


Ahlborg, B., et al. 1967. Muscle glycogen and muscle electrolytes during prolonged physical exercise. Acta Physiologica Scandinavica, 70, 129–42.

Billat, L.V. 2001. Interval training for performance: A scientific and empirical practice. Special recommendations for middle- and long-distance running. Part I: Aerobic interval training. Sports Medicine, 31 (1), 13–31.

Child, R.B., Wilkinson, D.M., & Fallowfield, J.L. 2000. Effects of a training taper on tissue damage indices, serum antioxidant capacity and half-marathon running performance. International Journal of Sports Medicine, 21 (5), 325–31.

Davis, J.M., & Bailey, S.P. 1997. Possible mechanisms of central nervous system fatigue during exercise. Medicine & Science in Sports & Exercise, 29 (1), 45–57.

Houmard, J.A., et al. 1994. The effects of taper on performance in distance runners. Medicine & Science in Sports & Exercise, 26 (5), 624–31.

Midgley, A.W., McNaughton, L.R., & Jones, A.M. 2007. Training to enhance the physiological determinants of long-distance running performance. Sports Medicine, 37 (10), 857–80.

Mujika, I., & Padilla, S. 2003. Scientific bases for precompetition tapering strategies. Medicine & Science in Sports & Exercise, 35 (7), 1182–87.

Mujika, I., et al. 2004. Physiological and performance responses to a 6-d taper in middle-distance runners: Influence of training frequency. International Journal of Sports Medicine, 23 (5), 367–73.

Sahlin, K., Tonkonogi, M., & Söderlund, K. 1998. Energy supply and muscle fatigue in humans. Acta Physiologica Scandinavica, 162, 261–66.

Shepley, B., et al. 1992. Physiological effects of tapering in highly trained athletes. Journal of Applied Physiology, 72 (2), 706–11.

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About the Author

Jason Karp, PhD

Jason Karp, PhD IDEA Author/Presenter

A professional running coach, freelance writer, fitness consultant and PhD candidate in exercise physiology at Indiana University. He coaches runners of all levels through