How well one can run depends on a number of individual physical and psychological variables. Some thereof are fixed, can not be changed or improved by training; examples are the size and proportions of the skeleton. Many however are trainable, and the goal of running training is to improve them in a desired direction. A list of such improvable variables:
A discussion of each of these follows.
In general, the "shape" of a movement, and the speed wherewith one can execute it, can be improved by thinking and reading about it to decide the proper form and then performing it many times. The motor nerves involved become faster and more efficient as the movement is executed often.
When one often runs long and slow, there is a tendency for one's technique to deteriorate, for the movements to become smaller. One gravitates to smaller movements as those are more efficient on long distances; and because slow running uses only the red muscle tissue, the unused white (fast twitch) fibres become thinner and less powerful, so that one loses muscle mass and strength. Red muscle fibres do not become thicker when used, unlike white fibres. Loss of strength subsequently leads to injuries like knee cap and knee problems.
Typical training forms done to get and maintain good coordination and technique are:
Such training forms have additional effects like improving strength and making the heart stronger; most training forms affect more than one aspect of running. It is usually not possible to completely isolate one variable.
Most of the injuries that bother runners are injuries of these tissues: tendons, nerve fibres, ligaments, cartilage, bone, and periosteum. These tissues have a metabolism but are more or less passive while running in that they do not apply any force by themselves. They have to endure the forces caused by the muscles and by the movements inherent to running.
They are mostly able to adapt to these forces by becoming stronger, but this takes time. When the strain increases faster than they can adapt to, injuries occur. About all of these running injuries are repetitive strain injuries. It is important to know that some tissues, like bones and tendons, have such a slow metabolism that they require a month for even the smallest adaptation. That is why injuries often occur while one tries to increase running training by the week. By the month is better.
The most purposive way to improve strength in these tissues are long, low-intensity efforts that resemble running, like walking, alternating walking with running, and, for advanced runners, continuous slow running. "Long" may be understood as "90 minutes to several hours".
How often one should do such training to improve or maintain this type of strength is an interesting question. Probably at least once a month for maintenance, and at least twice for improvement. More than about three times may be unwise because the long recovery time of these tissues may then keep one from doing other types of training. However, if one chooses to devote say one or two months entirely to this type of training (as a preparation for a subsequent period of more performance-oriented training), there is no objection to four, five, or more such sessions per month.
When running long and slow, there is a tendency for certain muscles to become weaker; this happens mainly to those at the front side of the body: the various muscles at the front of the lower leg, the various parts of the quadriceps on the front of the upper leg, and the various muscles on the front of the trunk. Weakness in those muscles is a common cause of chronic injuries, and also makes one slower and spoils one's technique.
Many non-running strengthening exercises exist to counteract this and improve strength, either with or without weights, and often done in "circuit" form. Also, running uphill, running over rough terrain, and in general running short and fast improve strength.
It is often said that one's numbers or proportions of fast and slow twitch muscle fibres are inborn and not trainable. This is not entirely true.
I have read that there are several more types of fibres than just these two, and that at least one thereof can, by training, be specialized into either "fast" (white, anaerobic) or "slow" (red, aerobic) tissue. So some change through training is possible in the number ratio between white and red fibres.
Also, the white fibres become thicker and heavier when trained (strength and speed training), while the red do not. So also the mass ratio between white and red tissue is trainable, provided one has some white tissue to start with. And the increase in white muscle mass can be very large if desired, as can be seen in body builders. An increase in white muscle mass may go at the expense of endurance though. The shorter the race distance one is training for, the more white muscle mass one needs. Also, running on rough terrain requires more of it than running on paved roads does, as short climbs and obstacles are typically taken anaerobically (so, using the white muscle tissue).
Flexibility determines the maximum length of one's steps or strides and thus plays its role, especially in running fast over short distances, which is done with much bigger steps than those seen in long distance running. It is also said that lack of flexibility is a cause of injuries, but this is less certain.
There exist many exercises to improve and maintain flexibility. I believe they are the most effective when done regularly in a separate session, apart from running training. In general, the muscles that are especially inclined to become tighter are those on the rear side of the body. Under stress, pain, or great effort, those muscles instinctively contract. This causes, for instance, the head to go backwards when in sudden pain.
This is a combined result of motor coordination, motor speed, technique, muscle strength, amount of white muscle mass, and flexibility. By improving or increasing those variables, sprinting speed is increased. If one only runs long and slow, sprinting speed goes down, except perhaps in people who have almost no white muscle fibres to start with and therefore have nothing to lose.
One may ask what the use of sprint training is for someone who only takes part in long distance races. Well, it is obviously of use in a finishing sprint, and also in situations like overtaking, accelerating, and short steep climbs.
But most importantly, the fastest long distance runners, with the exception of those with a rare one-sided talent for endurance, are those who "come from the track", who have a background in middle distance running and therefore have done a lot of training to improve their sprinting speed and technique. A lot of short, fast, anaerobic running. That is the natural order: first maximize your basic speed (which means sprinting speed in track language), then work on anaerobic endurance (sustaining that speed over several hundred metres to a kilometre), and finally go to the long distance, where aerobic endurance becomes the most important. In this process, the speed developed through sprint and anaerobic training is transferred as much as possible to a long distance pace. Runners who follow this course become faster on long distances than those who start out with long distance training and have never trained for short distances. Again, with the exception of pure endurance types who have no disposition for sprinting at all.
Something to keep in mind when trying to improve speed is that the faster one runs, the greater the need for a strong upper body becomes. The trunk muscles become ever more needed to keep the trunk in position so that one can "hit" one's centre of gravity well, and the shoulder and arm muscles become ever more needed for the arm movements that compensate the leg action. When the abdominal muscles are too weak, the trunk floats backwards when a certain speed is reached, and it becomes impossible to push off and hit the centre of gravity, and one has to slow down until the trunk is back in position again. So those muscles are the first that need to be trained. Then the back muscles need strengthening, because otherwise the now stronger muscles on the front pull the lower back convex, which can cause spinal disks to herniate. Finally the arm and shoulder muscles need to become stronger to deal with the ever greater forces caused by the leg movements.
When a high velocity is sustained beyond the natural sprinting distance, an energy system begins to be used that processes glycogen into energy without requiring oxygen, resulting in the formation of lactate or lactic acid. This is uncomfortable and forces one to stop running, after which the lactate is cleaned up by breathing. Through training one can learn to sustain such an anaerobic pace ever longer, beyond a kilometre even, be it that after about 500 or 600 metres the aerobic systems join in so that it becomes a combined anaerobic/aerobic effort. This combined use of anaerobic and aerobic systems is always needed to reach one's maximum performance over a given middle or long distance.
Anaerobic training usually consists of repeated fast runs over a few hundred metres with long recovery in between, like several minutes. The number of "repeats" is kept low, like two to six. The distance to start with must be chosen so that one feels significant anaerobic discomfort toward the end. This will be in the order of 250 or 300 metres. After a few such sessions, progress is made by gradually increasing the distance, and not by shortening the recovery intervals or doing ever more repeats.
The effects of this type of training are multiple. First, the regeneration of the phosphate energy system, that is used during the first 100 or 150 metres of such a run, improves. These phosphates supply energy without formation of lactate, and are only present in very small amounts, quickly exhausted, and regenerated during the recovery break. Second, the anaerobic threshold shifts to a higher speed, meaning one can run faster before anaerobic discomfort occurs, or has less discomfort at a given pace. Third, one simply learns to endure the discomfort better, similar to practising in holding one's breath.
Defenders of pure aerobic training have said, "you can not train oxygen debt". They are wrong in two ways: (1) You can train it, learn to endure it; (2) They ignore the first two effects explained in the previous paragraph.
When running for more than about 500-600 metres, the energy is supplied partly or entirely by aerobic systems; that is, by using the inhaled oxygen to convert glycogen and fat into energy. At low intensities such as walking or very slow running, body fat is used, and at higher intensities, glycogen, stored in the muscles and liver, is the fuel. Glycogen is a macro form (polymer) of glucose, that is, it consists of many glucose molecules bound together.
The possible improvements through training to these systems are described in great detail in many books, as aerobic endurance is generally considered the most important aspect of running, both for running itself and for general health. In short, it concerns things like the heart, the lungs, the blood, the blood circulation, the red muscle fibres, the fat metabolism, and the amount of glycogen one can store.
Training for aerobic endurance is done either by continuous running at a moderate speed (somewhat below the anaerobic threshold) over distances between say 1500 and 18 000 metres (there is of course no true upper limit), or by aerobic forms of intervallic training. Aerobic interval training differs from anaerobic training in that it has a lower intensity (not exceeding the anaerobic threshold), much shorter recovery breaks, many more "repeats", and a greater choice of distances for the repeated runs. Any distance from about 100 to about 2000 metres works (again, no real upper limit, but the number of "repeats" becomes very low with distances over 2000 metres). The total distance run in intervals is usually between 1500 and 10 000 metres. Progress is made by increasing the number of repeats and/or shortening the resting pauses, not by increasing the distance of the runs.
If the method of continuous running is used, 1500 metres is a good distance to start with, and progress can be made by gradually increasing the distance, going to 2000, 2500, 3000, 4000, and so on. But even 1500 metres, even once a week, at the pace meant here, has a significant effect on aerobic endurance.
It is generally assumed and recommended that one must first maximize one's aerobic endurance, before starting with anaerobic training. I am not entirely certain if that is always true.
Perhaps a few semantic remarks are in place: In interval training, the word "interval" refers to the resting break in between the runs (but many use it for the runs). The word "repeats" is often used to indicate the number of runs, but of course the actual number of runs is always one greater than the number of repeats. If you run ten times 100 metres, that is one original and nine repeats.
Excess weight only slows one down, so to run as well as possible one's fat percentage must not be higher than needed to maintain good health. This value differs per sex, and I think it also differs per individual and has a genetic basis. If you go under your personal minimum fat percentage, your shape deteriorates and you become unhealthy. Unfortunately it is awkward for the lay person to measure fat percentage the real way, which I think goes with a kind of pliers. Methods to get a rough indication are tables for estimating fat percentage from body mass and height, computing the body mass index (B.M.I.), measuring waist circumference, and computing the waist/hip ratio. A disadvantage of some of those methods is that they do not take muscle mass into account; that they do not allow for the fact that a muscular person must be heavier and have a greater B.M.I. than a slender person.
The typical slender long distance runner has a B.M.I. in the order of 18.5 to 20 and weighs less than than 360 grams per centimetre of one's height, but for muscular types this is not true.
When trying to lose fat, one must watch out not to lose muscle mass instead, which may happen if one eats to little carbohydrates (and protein, to a lesser extent) after and during training sessions. One may also lose muscle mass if one only runs long and slow and leaves out all speed and strength training. To know if one is eating enough, it is needed to monitor things like body mass and waist circumference regularly. If one loses mass but not fat (e.g. if waist circumference stays the same), something is wrong.
The best, safest way to lose fat are long (several hours), low-intensity activities, like walking, cycling, alternating walking with running, and so on. At the same time one must of course not eat significantly more kilojoules than one is burning up. It is not so that with low-intensity activity one uses more energy than with high-intensity activity (some misunderstand it that way), but it is simply so that a high-intensity activity can not be kept up long enough (and without causing injury) to safely use the amount of energy that can be consumed with hours-long low-intensity activity.
It pays off to think about and make plans for these aspects of a race, and mentally rehearse them so that they will not be forgotten when the time has come. It starts with choosing position before the start. When there are more than about a hundred people waiting for the starting gun, it is needed to decide beforehand where in that pack one wants to start. For a fast start one must stand near the head of the pack, and for a conservative, slow start, it is better to start in the rear.
In a race over a long distance that one has not or rarely run before, a slow start is usually the best approach. Halfway one may then accelerate if one still feels up to it. In short races up to about 5000 metres, or longer distances that one has run often, it is needed to start at a predetermined fast pace to reach one's maximum performance.
Once started, one may for several hundred metres be in a situation of overtaking and/or being overtaken, until one is running among others with the same speed. If one is following a fast start strategy, there will come a point where it gets unpleasant as a result of "oxygen debt". One must be mentally prepared for that, and have decided what to do. Often it helps to focus on keeping good (large enough) arm movements, to thus maintain the pace despite discomfort. If one has not decided what to do beforehand, one will probably slow down under oxygen debt and lose much time.
Toward the finish, over the last kilometre or the last several hundred metres or the last fifty metres (whichever suits one best), one will want to accelerate insofar still possible. Therefore it is needed to have information about the course, so that one will know where the last kilometre — or whatever — begins.
In training, the function of shoes and other clothing is to protect one from injury, cold and rain. Or from heat and sun, in some countries. But in races, what matters is that everything is as light as possible, because lighter means faster. This is especially true for the shoes and socks. When a foot is on the ground, its velocity is zero. After pushing off, it has to catch up with the moving body, so it has to accelerate in a fraction of a second from zero to probably twice the running speed. Acceleration requires force and energy, and computations show that in fast running it can amount to 30 m/s2 or more. In other words, the foot becomes about three times its weight in the acceleration phase. The greater the mass of the foot, the more force and therefore energy are required for the acceleration. This the main reason why light race shoes are faster than training shoes. I have estimated this to be in the order of 50 seconds per 10 kilometres, but of course it depends on the exact weight of the shoes compared, and on how fast one runs.
Also it makes sense to wear a watch or stopwatch during races, to observe the time passed at intermediate points along the course. Thus one is as it were guided in one's effort by the knowledge of how one is doing. And a guided vehicle is faster than a freely moving one.
In races longer than about 15 kilometres it is needed to drink and perhaps eat while running. This is something that has to be practised, or it will cause cramps in the abdomen during the race. The internal processing of water and food while running can be trained just like running itself.
If one has trained well and is looking forward to a race, this may go with great excitement and tension in the hours before the race, and make it hard to sleep in the preceding night. A good precaution is to make sure to sleep well and much in the night before the night before the race. And for race day itself, one may make a plan or list of what has to be done, and what needs to be packed and taken to the race. Thus one is as it were guided through the day, which helps to deal with the tension, the nervousness.