Skeletal Muscles fibres consist of slow and fast twitch fibres known as (type I) and (type II) respectively, as reflected by their enzyme activity patterns, they are characterized by their specific metabolic properties. Type I fibres are always ‘oxidative’ and Type II fibres display a wider range with “oxidative” and “glycolytic”. As a result, type I and type II fibres can be classified independently because of their characteristics. In this context, activity ratios between enzymes of anaerobic and aerobic pathways can be used as discriminative parameters. Similarly, specific ratios of enzymes catalysing unidirectional reactions in hexose metabolism separate the two fibre populations. The histochemical defined Type I and Type II cannot be separated into distinct metabolic groups. In view of the continuum of metabolic properties, skeletal muscle is an extremely heterogeneous tissue in which each fibre represents a separate metabolic compartment.
However, there are 3 main component of energy source which we must understand in order to further explain the characteristics of an elite swimmer going through the various distances of 50m, 400m and 1500m.The 3 component are the phosphagen system, glycolytic and aerobic system.
1. Phosphagen System – Each muscle cell has some amount of ATP. Adenosine triphosphate (ATP) is the way your body uses biochemical to store and use energy. There is sufficient ATP in the cell that the muscle that can use immediately, but only enough to last for about three seconds which is also known as anaerobic energy. The muscle requires replenishment of ATP levels quickly, using a high-energy phosphate compound called creatine phosphate (CP) allowing the phosphagen system to turn ADP back to ATP.
2. Glycolytic System – An energy system used for all-out exercise lasting from 30 seconds such as 100m sprinting on track and 100m swim. As we know during glycolytic, carbohydrate (the stored form of glucose) is broken down to form pyruvate. During this process through glycolysis 2 molecules of unused ATP will be form. Hence depending on the stored carbohydrate, it is recommended for short distance between 50m to 100m for an elite swimmer.
3. Aerobic System – An energy which requires oxygen, which is the most complex amongst the 3 energy systems. Aerobic metabolism is the slowest to resynthesize ATP to allow swimmer to prolong longer distance swim. Hence the way how an elite swimmer able to substance such a long distance without losing their staminal is to benefit the initial phosphagen or glycolytic to generate the initial pace, which eventually using up the anaerobic energy. Then the aerobic energy will kick in to prolong the subsequence distance.
Shorter distance swim event demand greater anaerobic energy systems. This is particularly true of the 50 metres, 100 metres and 200 metres events, which last between 20 to 120 seconds. The longer events, such as 800 metres to 1800 metres, would requires greater aerobic energy system to allow swimmer to prolong the distance. Evidence for this comes from blood lactate concentrations following 100 metres and 200 metres competition swims, which are a very high 16 to 20 mmol/L, suggesting that a great deal of energy is derived from the anaerobic breakdown of glycogen, resulting in lactic acid as a by-product. The highly anaerobic nature of sprint swim events would support the argument for more high-intensity and less high-volume training.
However, it is wrong by assuming by doing training is the best way to reduce lactate concentration. This concept is bases on the understanding that high lactate is bad and will affect the negative impact on athlete performance. Such understanding will affect the training programs that focuses on lactate threshold training to improve the lactate to enhance the ability of aerobic system to generate more energy for a required event.
There are two problems with this model of training:
Athlete need to understand the negative of high lactate level training. As we know that Lactic acid is a by-product from anaerobic breakdown from glycogen. It is spilt into H+ ion and lactate ion. As we know that acidic H+ ion is the bad guy which interfering with force production in the muscles which reducing the rate of glycolysis and will eventually slow down an athlete. However, lactate ion is simply being diffuses within the muscle into the bloodstream with no negative impact on athlete muscle function or energy production. This in fact will allow lactate ion to be recycle within the energy reproductive cycle to help produce energy used positively. Therefore, having a high level of lactate in blood is not a bad thing by itself. It is and indicator that there is a lot of anaerobic energy being generated. The training adaptation that an athlete is seeking is not a reduction in lactate production, but an increase in the buffering of the H+ ion. Training at high intensity and generating high levels of lactic acid helps the body get used to the increase in H+ within the muscles and improve its ability to enhance the acid;
Knowing that anaerobic glycolysis consists the fast breakdown of glycogen into energy-giving phosphates for sprint swimmers and aerobic glycolysis involves a much slower breakdown for long distance swimmers. It is possible for anaerobic energy systems produces maximal power and high speeds, as the muscles would not get a fast supply of energy. An athlete can generate high power, if he/she must have high levels of anaerobic energy supply.
For sprint swimmers, anaerobic capacity is the good guy and it require high intense training to develop. An athlete would require to be more anaerobic if an event demand on anaerobic system such as 50 metres, 100 metres and 200 metres events. In order to reduce the lactate level by adopting a high-volume aerobic are in fact compromising an athlete anaerobic fitness, which is one of the most important energy system to success in sprint swimming. To keep the lactate level low, athlete needs to gear up their lactate threshold in sprint swimming. Distance such as 200 metres, the high level of lactate is not a matter. For 800 metres and 1500 metres, aerobic system would be more important. In order to prolong a longer distance swim, lactate threshold training would be appropriate as he/she need to maintain an intensity which is much longer relying on aerobic energy system.
In conclusion, the overall above mention is to focus more training time at high intensity at the above mention event by setting the appropriate race pace. Thus, this will provide greater benefits to allow swimmers to distance longer at much slower than race speeds