How to develop a good solid base on which to build speed.
Brian Mackenzie explains the body's energy systems and the objective of endurance training.
A good base of endurance and strength is vital before the specific speed, and strength requirements of the athlete's sport/event can be developed if you wish your athlete to avoid injury. The objective of endurance training is to develop the energy production system(s) to meet the demands of the sport/event.
What are the energy production systems?
In the human body, food energy is used to manufacture adenosine triphosphate (ATP) the chemical compound that supplies energy for muscular contraction. Since ATP is in very low concentrations in the muscle, and since it decreases only to a minor extent, even in the most intense voluntary contraction, tightly controlled energy pathways exist for the continual regeneration of ATP as muscular contraction continues. For continuous exercise, ATP must be re-synthesised at the same rate as it is utilised. There are four types of endurance: Aerobic, Anaerobic, Speed, and Strength endurance. A sound basis of aerobic endurance is fundamental for all events.
The distribution of aerobic to anaerobic endurance for the runner is approximate:
During aerobic work (aerobic means 'with oxygen') the body is working at a level that the demands for oxygen and fuel can be meet by the body's intake. The only waste products formed are carbon dioxide and water. These are removed as sweat and by breathing out.
Aerobic endurance can sub-divided as follows:
Aerobic endurance is developed through the use of continuous and interval running
During anaerobic work (anaerobic means 'without oxygen'), involving maximum effort, the body is working so hard that the demands for oxygen and fuel exceed the rate of supply and the muscles have to rely on the stored reserves of fuel. In this situation waste products accumulate, the chief one being lactic acid. The muscles, being starved of oxygen, take the body into a state known as oxygen debt. The body's stored fuel soon runs out, and activity ceases - often painfully. Activity will not be resumed until the lactic acid is removed and the oxygen debt repaid. Fortunately, the body can resume limited activity after even only a small proportion of the oxygen debt has been repaid. As lactic acid is produced the correct term for this pathway is lactic anaerobic energy pathway. The alactic anaerobic pathway is the one in which the body is working anaerobically but without the production of lactic acid. This energy pathway can exist only so long as the fuel stored in the muscle lasts, approximately 4 seconds at maximum effort.
Anaerobic endurance can be sub-divided as follows:
Using repetition work of relatively high-intensity with limited recovery can develop anaerobic endurance.
The anaerobic threshold, the point at which lactic acid starts to accumulate in the muscles, is considered to be somewhere between 85% and 90% of your maximum heart rate.
Speed endurance is used to develop the coordination of muscle contraction in the climate of endurance. Repetition methods are used with a high number of sets, a low number of repetitions per set, and intensity greater than 85% with distances covered from 60% to 120% of the racing distance. Competition and time trials can be used in the development of speed endurance.
All athletes need to develop a basic level of strength endurance. Examples of activities to build strength endurance are - circuit training, weight training, hill running, harness running, fartlek, etc.
Energy production is both time and intensity-related. Running at a very high-intensity, as in sprinting, means that an athlete can operate effectively for only a very short period.
Running at a low-intensity, as in gentle jogging, means that an athlete can sustain activity for a long period. The training introduces another variable, and the sprinter who uses sound training principles can run at a high intensity for longer periods. Similarly, the endurance athlete who uses sound training methods can sustain higher intensities during a set period. There is a relationship between exercise intensity and the energy source.
D. Matthews and E. Fox, in their book, "The Physiological Basis of Physical Education and Athletics", divides the running requirements of various sports into the following "energy pathways": ATP-PC and LA, LA-02, and 02.
These energy pathways are restricted by time. In other words, once a certain time elapses that specific pathway is no longer used. There is some controversy about these limitations, but the consensus is:
The result of muscle contraction produces ADP which when coupled with PC (stored in the muscles) regenerates ATP. Actively contracting muscles obtain ATP from glucose stored in the bloodstream and the breakdown of glycogen stored in the muscles. Exercise for longer periods requires the complete oxidation of carbohydrates or free fatty acids in the mitochondria. The carbohydrate store will last approx. 90 minutes and the free fatty store will last several days. All three energy systems contribute at the start of exercise, but the contribution depends upon the individual, the effort applied, or the rate at which energy is used.
The Anaerobic (ATP-CP) Energy System
Adenosine Triphosphate (ATP) stores in the muscle last for approximately 2 seconds and the resynthesis of ATP from Creatine/Phosphate (CP) will continue until CP stores are depleted approximately 4 to 5 seconds. This gives us around 5 to 7 seconds of ATP production. To develop this energy system, sessions of 4 to 7 seconds of high-intensity work at near-peak velocity are required. e.g.
The Anaerobic Lactate (Glycolytic) System
Once the CP stores are depleted the body resorts to stored glucose for ATP. The breakdown of glucose or glycogen in anaerobic conditions results in the production of lactate and hydrogen ions. The accumulation of hydrogen ions is the limiting factor causing fatigue in runs of 300m to 800m. Sessions to develop this energy system:
There are three different working units within this energy system: Speed Endurance, Special Endurance 1, and Special Endurance 2. Each of these units can be developed as follows:
The Aerobic Energy System
The aerobic energy system utilises proteins, fats, and carbohydrates (glycogen) for resynthesising ATP. This energy system can be developed with various intensity (Tempo) runs. The types of Tempo runs are:
Sessions to develop this energy system:
Energy System recruitment
Although all energy systems turn on at the same time, the recruitment of an alternative system occurs when the current energy system is almost depleted. The following table provides an approximation of the percentage contribution of the energy pathways in individual sports. (Fox et al. 1993)
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About the Author
Brian Mackenzie is a British Athletics level 4 performance coach and a coach tutor/assessor. He has been coaching sprint, middle distance, and combined event athletes for the past 30+ years and has 45+ years experience as an endurance athlete.