Here you can learn all about Training Gains – An Advanced Series Of Articles For Experienced Trainers!
Muscle Fibre Types: The Right Position ?
Every time I ask the following questions I always get the same puzzled look as I’m about to get now.
Let’s say that a 100m runner with a 100m time of 10.9 seconds comes to you for coaching. How do you know that this athlete is performing in the correct discipline that will enable them to attain success ? How do you know whether they would be better suited to a short, intermediate or a longer distance ? How do you know that the 100m sprinter that asks to be coached is capable of running any faster than they are doing now ?
An arrogant or ill informed coach will immediately jump to the conclusion that all that is required are his / her training methods, methods which are tried, tested and guaranteed to bring out the very best in anyone willing to apply themselves.
A good, well educated coach, on the other hand, will send any athlete, at the earliest possible age, to have a muscle fibre test. Muscles fibres, based on genetics, pre determine who is capable of developing the ability to run given distances and who, sadly, is not. This will save years of time, effort and performing the wrong training which has been based upon assumptions rather than fact.
Red Slow Twitch Muscle Fibers:
Slow Oxidative Type 1 Twitch muscle fibres contract efficiently in the presence of oxygen during aerobically based activities. Oxidative fibres have a high myoglobin content, which not only helps support their oxygen dependency, but also imparts a red colour to them, just as oxygenated haemoglobin is responsible for the red colour of arterial blood.
Accordingly, these muscle fibres are referred to as red fibres. Slow Twitch muscle fibres have the ability to use fat as a fuel source, but only during aerobic conditions. Fat cannot be mobilised for energy without the presence of oxygen and carbohydrate.
Intermediate Muscle Fibres:
Intermediate Slow Oxidative Type 2a Twitch muscle fibres share characteristics of both other fibre types. They can adapt to use A.T.P. like the fast twitch fibres, as well as having a high oxidative capacity like the Slow Twitch fibres. They contract more rapidly than the Slow Twitch fibres and can maintain the contraction for longer periods of time than the Fast Twitch muscle fibres. In humans, most of the muscles contain a mixture of all three types. The percentage of these various fibres not only differs between muscles within an individual, but also varies considerably among individuals. You cannot increase the total amount of muscle fibres, but you can increase the proportion of existing muscle fibres by manipulating training so that the intermediate muscle fibres adapt, and increase the proportion of either Fast or Slow Twitch muscle fibres, which takes up to three weeks.
White Fast Twitch Muscle Fibres:
Fast Glycolitic Type 2b twitch muscle fibres are used during short bursts of energy and physical activities that are predominantly anaerobic in nature, e.g. fast sprints. They contain an abundance of glycogen for energy. These glycolitic fibres contain very little myoglobin and therefore are pale in colour, so they are sometimes called white fibres. Fast twitch muscle fibres use primarily the A.T.P – pcr and Lactic Acid energy systems. Therefore, the amount of each type of muscle fibre you possess may have important implications for weight training and certain sports. Although not everyone has the potential to perform at elite level, it is still possible to maximise the capacity of each of the three energy systems by adopting specific training strategies.
People with a higher percentage of white fast twitch muscle fibres will automatically be good candidates for achieving results in strength, bodybuilding and power training strategies, whilst those with a greater proportion of red slow twitch muscle fibres are more likely to gain optimum results in endurance based activities.
During any 4 to 6 or 8 to 12 week meso cycle, regardless of whether you are training for bodybuilding, endurance, strength training, cardiovascular fitness, or fat burning, you must always use exactly the same exercises during the entire meso cycle so that you ensure maximum muscle fibre recruitment and that the body can learn the most effective way in which to perform these exercises, the most efficient way of processing nutrients and removing waste products, and also the best way of maintaining and recovering from the demands imposed.
Apart from the type and length of training, nutrition and rest days, gym or endurance, gains will be highly dependent on the percentages of the relevant muscle fibre types that the trainer possess.
After the first few weeks of training gains will be further increased as a result of the intermediate fibres adapting to the type of overload / training performed, thus becoming more efficient. As they do so they either convert to fast or slow twitch muscle fibres. This is why (allowing for all other factors that affect achieving gains, such as the type and length of training, nutrition and rest days) after the first 4 to 6 weeks, people with a large proportion of intermediate muscle fibres make surprisingly fast gains either in terms of endurance or muscular gains.
The reason for this 4 to 6 week time scale is due to the fact that the first two weeks of a new training cycle is where the muscle fibres are learning to recruit the existing muscle fibers in the best sequential order before you can get the optimum performance from those muscles. It will then take a minimum of another two weeks for the body to learn to recruit the pink intermediate muscle fibers. The new maximum output of that new exercise is therefore going to be 4 to 6 weeks.
The adaptation period will shorten for advanced trainers due their experience of training which conditions the muscles and energy pathways to recruit muscle fibres more effectively than trainers who have just started out. The exact length of the shortened time scale cannot be given as this will be totally dependent on the type of training and the genetics of the individual in question.
The average person possesses about 20% of intermediate fibres.
How does muscle fibre conversion work for multi event disciplines ?
As we have just seen, it can take upto 6 weeks to get the most effective performance from muscle fibres once they have converted and adapted to exercise. But this does not mean that it is going to take this amount of time for the Intermediate muscle fibres to be converted either way as a large amount of muscle fibres can be converted straight away. When we say upto 6 weeks we are talking about optimum efficiency performance for a specific exercise or sustained method of training, i.e. bodybuilding, or endurance sports etc.
When we talk about muscle fibre conversion from going from an anaerobic sprinting event to an aerobic endurance event, we are able to get a large amount, not all, of instantaneous muscle fibre conversion from the Intermediate fibres, but this will never be to the same optimum efficiency performance levels than if we were to just stick to exactly the same exercise or exactly the same method of training for a prolonged period of time.
Sport specific training geared towards mimicking the competition in the training will greatly improve the ability of the Intermediate muscle fibres to adapt from going from an anaerobic sprinting event to an aerobic endurance event, but again, this adaptation will never be to the same optimum efficiency performance levels than if we were to just stick to exactly the same exercise or exactly the same method of training for a prolonged period of time.
If you do mainly aerobic work and then intersplice this with some anaerobic work, the anaerobic work will suffer because you are not doing the same amount of volume in the anaerobic work.
You cannot say how much muscle fibre conversion will happen from race to race as this research has never been done.
Muscle Fibre Percentages:
It is important to note that the fibre percentages do not change as a person grows older. You will have the same percentages of muscle fibres as a child that you will possess as an adult. Nor do the actual number of muscle fibres change. For example, if you have 10,000 muscle fibres before beginning a training programme, then you will still have 10,000 muscle fibres after the training programme. Muscle fibres get thicker, and the internal, not the overall, percentages change as the intermediate muscle fibres adapt and convert to either fast or slow twitch muscle fibres.
• The average person’s muscle fibre percentages
40% Red Slow Twitch
20% Pink Intermediate Twitch
40% White Fast Twitch
With these muscle fibre percentages there is no chance of being a champion even with the best “chemical assistance“.
• An elite Ethiopian runner’s muscle fibre percentages
80% Red Slow Twitch
10% Pink Intermediate Twitch
10% White Fast Twitch
• Daley Thompson’s muscle fibre percentages
10% Red Slow Twitch
80% Pink Intermediate Twitch
10% White Fast Twitch
• A good blend for middle distance runners
70% Red Slow Twitch
20% Pink Intermediate Twitch
10% White Fast Twitch
To have a chance of being a champion at a given sport you need to have more than 70% of the specific muscle fibres required for that sport, 70% representing a very borderline chance of being a champion. 75% plus is required to have any chance of being a champion.
A Closer Look At Muscle Fibre Conversion:
What is the difference between having the following muscle fibre percentages when training to be a cross trainer or decathlete ?
40% Aerobic Fibres / 20% Intermediate Fibres / 40% Anaerobic Fibres
10% Aerobic Fibres / 80% Intermediate Fibres / 10% Anaerobic Fibres
It would seem that both percentages would give the same result as in both the examples above the conversion of Pink Intermediate muscle fibres would yield the same percentages of aerobic and anaerobic fibres, i.e. 50% aerobic fibres and 50% anaerobic fibres.
The difference lies in the fact that the Pink Intermediate fibres are the fibres that can convert to being either aerobic or anaerobic fibres. This means that elite level athletes who are highly trained will be able to more quickly convert the 80% of Pink Intermediate muscle fibres to meet either aerobic or anaerobic needs, whereas in the first example there is only a potential of 20% Pink Intermediate fibres that will be available for conversion.