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1. Maximal Oxygen consumption (V0₂ max)
2. Lactate/anaerobic threshold (OBLA-onset of blood lactate accumulation)
3. Efficiency or running economy

The first requirement is oxygen delivery, which needs a high maximal blood supply to transport a greater amount of oxygen and the potential for more muscle to be active during exercise. V0₂ max is limited by the pumping capacity of the heart and the arterial development to the muscle. The heart is a muscle and can be remodelled as a result of endurance training, developing greater ventricular volume and diameter, this will result in greater stroke volume and other subtle changes, which results in greater blood volume. An increase in blood volume in conjunction with higher stroke volume results in improved cardiac output which will ultimately provide a more efficient oxygen delivery system.

Second is the ability to utilise this delivery of oxygen, the more intense work we can achieve before the onset of inhibiting blood lactate accumulation the faster the sustained pace we can tolerate.When we are in an untrained state we are limited by the lack of capillary density, fatty acid breakdown, enzyme levels and mitochondrial density in the task specific skeletal muscles.

Last but not least is the economy in which we are able to perform the sport specific task. Efficiency links sustainable power to performance. The more efficient or economical we are the greater velocity we can achieve at any given level of energy output. Various methods of improving form, efficiency, and technique can be achieved through different types of strength conditioning. I will cover specific strength training & conditioning in another article.

In endurance events the goal is always the same. We attempt to maximise our achieved performance velocity. Endurance sport demands a combination of high oxygen transport, resistance to fatigue and a high transfer of physiological work to mechanical movement. On race day performance potential is linked to psychological factors and our accuracy of pacing. The end product is achieved performance velocity.
These factors are not independent of one another but are interdependent on each other. Each sport discipline place specific demands on the system and are challenged by the unique resistance to movement throughout the event. It is important to keep in mind that lactate threshold is more specific to the mode of exercise than it is to V02 max.

A study performed by Coyle et al. published in 1991 showed that 14 competitive cyclists with near identical V0₂ max levels had differing Lactate Thresholds when compared during testing on the bike. The group was broken into those with low LT (66% of V0₂ max) and those with high LT’s (above 86% of V0₂ max). They were than asked to perform the test again on a treadmill and the outcome was that both groups scored above 80% of V0₂ max. Further study revealed that the group that tested with the lower LTs on the bike did not have the same cycling experience (2.7 years), as did those with the higher scores (5.1 years) yet the two groups had experienced similar over all endurance training experience (7-8 years).

The conclusion is that efficiency is not immediately transferable. Efficiency is about getting more work done at a lower cost of energy. In studies carried out at the university of Texas on Good vs. Elite cyclists it appeared that elite riders sustain higher power output despite similar physiological values in part by learning to distribute pedalling force over a larger muscle mass. Based on a tremendous amount of both laboratory and field data the order in which performance variables are most effective is 1. V02 max, 2. Lactate threshold 3. Performance efficiency. However if you are new to endurance sport  all three variables will improve no matter what order you apply them.

To improve endurance, athletes must learn to overcome fatigue, and they do this by adapting to the training demand. Any degree of adaptation will result in improved endurance. Athletes must develop the two types of endurance, aerobic and anaerobic, primarily according to the specifics of their sport or event. Developing these two types of endurance depends on the type of intensity and the methods used in training.

Aerobic Capacity The aerobic potential, or the body’s capacity to produce energy in the presence of oxygen (0₂) determines the athlete’s endurance capacity. Aerobic power is limited by the ability to transport 0₂ within the body. Developing the 0₂ transport system should therefore be part of any program to improve endurance. High aerobic capacity, which is vital to training, also facilitates faster recovery during and after training. A rapid recovery allows the athlete to reduce the rest interval and perform work at a higher intensity. As a result of shorter rest intervals, he or she can increase the training volume.

A high aerobic capacity positively transfers to the anaerobic capacity because of the ability to function longer before reaching 0₂ debt. A high aerobic capacity also stabilises speed as a result of long duration training sessions at varying intensities the body learns to regenerate and thus increase the durability of anaerobic power.

Not all of the mechanisms that are responsible for improving muscular strength and endurance are fully understood. Nevertheless, we have been able to identify many of the metabolic and cellular changes that accompany specific endurance based training. Aerobic training, for example, leads to improved central and peripheral blood flow and an enhanced capacity of the muscle fibres to generate greater amounts of ATP (adenosine triphosphate)the body’s fuel.

Aerobic base training promotes structural as well as functional changes in the body of which the most critical effects are.

Muscle Fibre Adaptation     

Capillary Supply

Myoglobin Content    

Mitochondrial Function

Enhanced Oxidative Enzymes

Muscle Fibre Adaptation In response to aerobic based training ST (slow twitch) fibres become 7 to 22% larger than the corresponding fast twitch fibres FT . Studies have shown that endurance training does not change the percentage of ST and FT fibres. Human muscles contain a genetically determined mixture of both slow and fast fibre type. On average, we have about 50% slow and 50% fast fibres in most of the muscles used for movement. The slow muscles contain more mitochondria and myoglobin which make them more efficient at using oxygen to generate ATP without lactate acid build up.

Evidence tends to support the concept of subtle changes among FT fibre subtypes. FT ll _b fibres are apparently used less often than FT ll_a fibres, and for that reason they have a lower aerobic capacity. Long duration exercise eventually recruits these fibres into action, demanding them to perform in a manner normally expected of the FT ll_a fibres. Evidence indicates that years of endurance training can cause FT ll_b fibres to take on characteristics of the more oxidative FT ll_a fibres. This subtle conversion of FT ll_b to FT ll_a fibres may reflect the greater use of fast twitch fibre during long, exhaustive training.

Capillary Supply One of the most important adaptations to endurance training is an increase in the number of capillaries surrounding each muscle fibre. With long periods of endurance training the number of capillaries have been shown to increase by as much as 15%. Having more capillaries allows greater exchange of gases, heat, wastes, and nutrients between the blood and working muscle fibres. Substantial increases in muscle capillary number will occur within the first few months of training.

Myoglobin Content Once oxygen has entered the muscle fibre, it is transported within the cell by myoglobin, a compound similar to haemoglobin. Myoglobins main function is to deliver oxygen from the cell membrane to the mitochondria. Aerobic training increases the myoglobin content of the muscles by as much as 75-80% which further enhances oxidative metabolism.

Mitochondrial Function Aerobic energy production is conducted in the mitochondria. Mitochondria are known as the “power house of the cells”, what they mean is that mitochondria get the energy out of glucose in respiration: they use this energy to make that wonderful chemical called ATP. The ability to use oxygen and produce ATP (adenosine triphosphate)via oxidation depends on the number and size of the muscle’s mitochondria. We know that as the volume of aerobic training is increased, so are the number and the size of the mitochondria. Glucose cannot be stored by cells so they must convert the glucose into glycogen ( Krebs Cycle). Both liver cells and muscle cells can then store glycogen, which can be used as fuel.

Oxidative Enzymes Increasing the number and size of mitochondria alone increases our muscles aerobic capacity, but these changes are further enhanced by an increase in mitochondrial efficiency, oxidative breakdown of fuels and the ultimate production of ATP depends on the action of mitochondrial enzymes. Endurance training increases these enzymes’ activities. All of these changes occurring in the muscles, combined with adaptations in the oxygen transport system, lead to enhanced functioning of the oxidative system and improved endurance.

Anaerobic Training The degree of adaptation to endurance training depends not only on training volume, but also on training intensity. Consider the importance of training intensity for performance in prolonged events. Muscular adaptations are specific to both the speed and duration of effort performed during training. Runners, Cyclists and swimmers who incorporate intermittent, high intensity bouts of exercise into their training show more improvements than those who perform only long low intensity training bouts. Long duration low intensity training does not develop the neurological patterns of muscle fibre recruitment and the high rate of energy production required for maximal endurance performance.

Anaerobic training increases the ATP-PCr (adenosine triphosphate – phosphocreatine) and glycolytic enzymes but has no effect on the oxidative enzymes. Conversely, aerobic training leads to increases in oxidative enzymes, but has no effect on the ATP-PCr or glycolytic enzymes. Physiological alterations result from highly specific types of training stimulus.

Adaptations Resultant from Anaerobic Training

Efficiency of movement     

Aerobic energetics (Glycolysis, Aerobic Oxidation )   

Enhanced buffering capacity

Training at high speeds improves motor skill and coordination at higher intensities, optimising fibre recruitment to allow more efficiency, which lends to economical use of the muscles energy supply.

Anaerobic training does not stress only the anaerobic energy systems, part of the energy needed for sprinting is derived from oxidative metabolism. Consequently, repeated bouts of sprint-type exercise (such as 30 sec. maximal efforts) followed by recovery enhances the muscles oxidative potential. A by-product of the production of the lactate is a free hydrogen ion (H+). This ion is what causes the burn in the legs. Excessive accumulation of the H+, caused by the increased production of the lactate, will eventually cause all muscular activity to cease. There is no such thing as "lactic acid", the H+ ion is the real acid that provides the "burn" that you feel.

Anaerobic training improves the muscles capacity to buffer the acid that accumulates within them during anaerobic glycolysis. Lactic acid accumulation is considered a major cause of fatigue during sprint type activity as it interferes with metabolism and contractile process in the muscles. Aerobic training does very little to assist in lactate tolerance.

Training the Energy Systems

In all athletic programmes, you must alter training intensity to enhance physiological adaptation and regeneration. Such alterations depend on the requirements of the event and the characteristics of the training phase. In consideration of the physiologic profile of an endurance event, energy demands are supplied by the phosphate system (ATP-CP) for the first 15-20 seconds, followed by the lactic acid system (LA) up to 1-2 minutes, as the event continues for a longer period, then energy demands are supplied by glycogen which in the presence of 0₂ is completely burned without producing lactic acid.

The following training systems are numbered in order of intensity

 (1) being the most taxing and (5) being the least taxing as the body can tolerate this effort much easier.

1. Lactic Acid Tolerance Training (LATT) The scope of LATT training is to adapt to the acidic effect of LA, buffer the effect and increase removal of lactic acid. Athletes who adapt and learn to tolerate LA can work more intensely and produce more LA, because it should not be inhibiting. Thus, toward the end of an event, the athlete can produce more energy anaerobically. Maximum LA accumulation can be met within 40 to 50 seconds and should be followed by recovery periods long enough to remove the LA from the working muscle. Caution must be exercised to insure adequate removal of LA in recovery or the desired effect may be lost as maximum speed diminishes during the training. This type of training must be used sparingly as to avoid potential injury and over training (max 1 to 2 times per week).

2.  Maximum Oxygen Consumption Training (Max V0₂) During training and competition, both parts of the oxygen delivery system, central (heart) and peripheral (capillaries at the working muscle), are heavily taxed to supply the required oxygen. Because the 0₂ supply at the working muscle represents a limiting factor athletes with large max V0₂ capacity demonstrate better performance. Increased max V0₂ results from improved transportation of 0₂ by the circulatory system, and increased extraction use of 0₂ by the muscular system. This training effect results from near maximal efforts for up to 3-5 minutes with rest intervals of 2-3 minutes.

3. Anaerobic Threshold Training (AnTT) AnTT refers to the intensity of an exercise at which level the rate of LA diffusion in the blood stream exceeds the rate of its removal. A training program designed to reach AnTT must produce LA at a rate beyond the ability to dispose of it. Such a program requires effort of medium intensity just above AT and should be sustained for up to 7-10 minutes with recovery being 1:1. During such training the subjective feeling of the athlete should be mild distress with speed slightly faster than what is comfortable.

4. Phosphate System Training (PST) The intent of PST is to increase an athlete’s ability to be fast with less effort. This is possible by applying short work periods of 4-15 seconds, with maximum effort. Such training develops the phosphate energy system and increases the quantity ATP-PC stored in the muscle. Work to recovery must be at least 1:4 in order to draw from the correct energy system. PST or sprint training should not cause muscle pain, If pain persists, this is a sign of anaerobic glycolysis and you are pulling from the LA system and will lose the desired training effect.

5. Aerobic Threshold Training (ATT) ATT is performed mostly through a high volume of work without interruption (uniform pace) The duration of an ATT session is generally from 90 minutes to in excess of 2-3 hours. It develops the functional efficiency of the cardio respiratory and nervous system and enhances the economical function of the metabolic system. Finally it increases the capacity to tolerate stress for long periods and quickens recovery.

Anaerobic Alactic Speed Work (True Speed & Power) 1 to 7 seconds

The energy for movement in the first 7 seconds comes from the splitting of ATP (adenosine triphosphate) into ADP (adenosine diphoshphate) and phosphate (P). Creatine Phosphate (CP) is then split to resynthesise ADP back into ATP. No oxygen is used with this energy system. High intensity work (power) utilizes the anaerobic alactic system.  This type of training must take place when fatigue is not present.  Most athletes require 48 to 72 hours of rest with low intensity before performing maximum speed or power work again. It is essential that the central nervous system be fully recovered before starting the next set.  Proper nerve patterning will not occur if fatigue is present.  Speed training should not be preceded with any other training but the standard warm-up.  Speed or power training should stop when maximum or near maximum speed cannot be achieved or maintained.

Training the Anaerobic Alactic System

The high end of the total distance run in one session is for advanced athletes

The time period for ATP and CP resynthesis is 50% for 30 seconds, 1 minute = 75%, 90 seconds = 80%, 3 minutes = 98% You must allow for adequate recovery if you want high quality work!

Anaerobic Lactate Work

The next demand for energy comes from the Anaerobic Lactate System (also known as Glycolysis). The breakdown of glucose (sugar) is used to produce 2 to 3 ATP. Ultimately the system shuts down around 60 to 90 seconds due to the accumulation of hydrogen ions (H+) that make the muscle cell acidic. The muscle cannot function in a highly acidic environment. No oxygen is present utilising this energy system.   High lactate tolerance work should only be done twice a week during a non-competitive pre-competition phase of training.  The methods to improve speed and speed endurance, whether it is anaerobic alactic work or anaerobic lactate, are very intense and fatigue the central nervous system. The optimal volume depends on the athlete’s background but generally the total volume is low.

Training the Anaerobic Lacate System

The high end of the total distance run in one session is for advanced athletes

The Aerobic System

The aerobic system is highly trainable. In the aerobic system, pyruvate (from Glycolysis) and fatty acids (stored fats) are oxidized to create energy for movement. The aerobic system produces 36 to 37 ATP. The aerobic system is a very efficient producer of ATP compared to the anaerobic system. All energy systems are always available for operation instantaneously. A higher level of aerobic conditioning supports higher levels of intensity and effectively postpones the point at which the muscular action becomes totally anaerobic, with the resulting production of inhibiting lactic acid and hydrogen ions (H+).   This type of training stimulates the development of mitochondria in the active muscle cells, increases heart volume, the capillary network feeding the active muscles and the heart, blood volume and haemoglobin content.

 Training the Aerobic System

Graham Smith B.A.F. Senior Coach

Level 4 Performance Coach

Level 4 Strength & Conditioning Coach

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