Endurance
In soccer, we understand that endurance is the ability to overcome resistance to fatigue. Generally, we speak of endurance in two different forms:
General Endurance, which is aerobic (with oxygen) and provides the player with long time endurance; and
Local Muscle Endurance, which is anaerobic (without oxygen) and corresponds to speed training and speed endurance training and provides for short- time endurance.
To develop general endurance, players are trained aerobically in order to improve the efficiency of the cardiovascular system. Aerobic training can be divided into three categories: aerobic low intensity or Aerobic Capacity, aerobic high intensity or Aerobic Power, and recovery training.
Players must also be able to maintain a level of fitness that permits them to execute technically throughout the game. In order to achieve this, training must focus on developing the ability to perform various running speeds for long periods of time. Aerobic capacity aids in developing this capacity.
Players must also be capable of performing at high intensities at any time during a game. This ability is developed through aerobic power training.
The most common analogy is that if the player is a car, then aerobic capacity corresponds to the size of the tank, while aerobic power corresponds to the engine power.
There should be a progression in the training. Ideally, adequate aerobic capacity should be reached first before switching to aerobic power training. Going back to the car image, the best car would still stop running without gas, no matter how much horsepower it has. Applied to the soccer player, a coach wants to make sure that his or her players are capable of simply running for 90 minutes (or less depending on the age group) before worrying about the running speed.
Another important aspect of conditioning is recovery and regeneration. Following a match or an intensive training session, players perform light physical activities that aid and allow for recovery. We refer to this as recovery training.
Aerobic Endurance (Cardiovascular) (With O2)
In a soccer match, activities like walking, jogging, and slow to moderate running are fuelled predominantly by the aerobic energy system. It is these activities that make up as much as 90-95% of a player’s performance.
Aerobic endurance conditioning will allow you to sustain these kinds of activities at a much higher level. It will also help you to recover following shorter, more intense exercise.
Even though a player may only sprint for a total of five minutes in a game, that still equates to forty or fifty all-out bursts. As a match progresses these short, sprints become slower and less sharp. Aerobic endurance training will help you to perform at the same level in the last ten minutes as you did in the first ten minutes.
The purpose of aerobic endurance training is to:
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Improve the heart and cardiovascular system so blood (and oxygen) can be delivered around the body more efficiently.
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Increase the body's ability to utilize oxygen.
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Increase the body's ability to recover from heavy bouts of intense exercise.
Anaerobic Endurance (Speed/Power) (Without O2)
High-intensity activities that last less than thirty seconds rely on the anaerobic system to provide energy. In soccer, these include jumping to win a header, catching a cross (goalkeepers), kicking and sprinting.
The anaerobic energy system can supply the body with ATP very rapidly. However, a by-product of this system, called lactic acid, quickly builds up in the muscles and causes fatigue.
A good example is repeating several maximal sprints back-to-back. Within a short while enough lactic acid will accumulate to cause you to either stop or dramatically slow down.
The ability to repeat short bursts of power in quick succession is a measure of your anaerobic endurance. The purpose of anaerobic conditioning is to:
• Help maintain bursts of power for longer
• Increase a player’s tolerance to lactic acid
• Speed up recovery by increasing the player’s ability to remove lactic acid
Heart Rate:
Reference has been made to heart rate in all three aerobic methods. This is an important measurement for determining the level of effort expended during training. During exercise the heart rate rises, which results in an increase in cardiac output. The maximum heart rate (MHR) can be determined by using different formulas.
The general formula is MHR = 220 – age
There is also a more refined, but still limited, formula where MHR = 205 –half the age.
However, there is a large range within a given age group. It has been found that boys and girls aged 16 to 19 had a range of 180 to 230 beats per minute for maximum heart rate. In order to make use of heart rate measurement it is necessary to determine the maximum heart rate for each player.
There are specific exercises that coaches may use to determine maximum heart rate; however, one of the simplest methods to determine a player’s maximum heart rate is to measure it immediately after a bout of presumed maximum intensity exercise during training. i.e., 1v1 or 2v2. In order to ensure that the true maximum heart rate has been obtained, the measurement should be repeated several times. Since a player’s maximum heart rate will not vary with changes in training throughout the season, it is only necessary to determine a player’s maximum heart rate once a year.
Measuring the heart rate at the end of aerobic capacity testing, because theoreti- cally these are conducted until exhaustion, will also constitute a great indicator of MHR.
By knowing maximum heart rate, we can easily determine the intensity of training for our players. For example, a heart rate of 170 bpm recorded during a training game could reflect a very high intensity for a player with a maximum heart rate of 180 bpm (reflecting an intensity of 94% of maximum heart rate). However, for a player with a maximum heart rate of 230 bpm, the exercise would be far less demanding, as 170 bpm would only reflect 74% of maximum heart rate.
But coaches should always keep in mind that maximum heart rate itself has nothing to do with ability or fitness. It’s a matter of genetics and cardiac efficiency. Only resting heart rate (RHR), usually about 60 beats per minute, can be considered as a fitness number when assessing the capacity of recovery or the level of endurance. Well-trained endurance athletes have a lower resting heart rate, which in extreme cases, can be below 30 beats per minute; they will also have the capacity to go down to RHR quickly after effort. One good indication of fitness level would be returning to RHR (+/- 10%) in one minute after the effort stops.
The best formula when working on heart rate training is the Karvonen formula:
Target training heart rate = (MHR – RHR) x % of intensity + RHR
This formula gives quick and reliable target heart rates for all the players.
Example:
Joe is a 20 years old midfielder, with a 50 bpm resting pulse and you want to work him out at 80%.
(195-50) X 0.8 + 50 becomes 145 x 0.8 + 50 becomes 116 + 50 = 166 bpm.
You then know that Joe, when training, should attempt to keep his heart rate close to, but always below, 166 beats per minute.
The "Vo2 Max"
VO2 Max refers to the amount of oxygen your body can consume during a maximal effort. This is measured in liters per minute per kilogram of body weight. The air we breathe has a set amount of oxygen. Obviously the bigger Vo2, the more air available, and potentially the more endurance and work rate a player will have.
Field tests or lab tests can give the coach a good idea of the player’s Vo2 max. These tests reflect how efficient your energy system is at supplying oxygen to working muscles.
While VO2 Max is primarily a genetic factor, this can be increased through training, perhaps by as much as 30 percent.
The VO2 max is one of the most popular indexes for endurance athletes. Professional strength and conditioning coaches working for soccer clubs or national teams often compare VO2 max readings.
Studies show that the average intensity for a professional game is around 75% of the Vo2 max.
In addition to aerobic capacity training, an interval training aerobic power workout, or Vo2 max training, will lead to an increase of oxygen consumption efficiency at the cell level. Some structural and enzymatic reorganization facilitates the energy amount produced by the aerobic system. For the same effort, less lactic acid is produced and its removal is accelerated.