FitVandaag - Still a sprint left or not?
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Why do some have a “final sprint” left in them and others don’t?
Last weekend I watched the World Cup Speed Skating and was wondering about the following: why some skaters totally collapse at the end of their race while others are capable of holding their speed right up until the finish, or even go faster? This phenomenon is especially seen in speed skating as there are different types of athletes riding against each other on the same distance. For example you see sprinters and endurance athletes riding 1,500 meters both using very different ways of riding and dividing their race. This concerns speed skating, however, this phenomenon can be seen in every sport: running, biking, swimming etc.
I have a number of thoughts that might shed some light on this phenomenon: it has to do with the energy sources that a man has at his disposal and with the muscles composition of an athlete.
First, our energy! We have three types of energy:
1 anaerobic alactisch - for short maximum efforts, it's actually less than 10 seconds fully available. We use it when we try to sprint or lift something really heavy. This system recovers quickly, within a few minutes you're basically almost 100% recovered. Team Athletes use this system a lot. During a match they do lots of short near maximal efforts, followed by relative rest.
2 Anaerobic Lactic - also known as the emergency system of our body. It’s also available for a short period, say between 10 and 90 seconds. This we use in a heavy, just not maximal at the start, exercise, but keep going fast until we are simply done. Physically very demanding and it takes a considerable amount of time before you recover. If you really use this system for 100% you are totally spend within those 90 seconds. It takes at least half an hour before you more or less recover but then you have to be fit. Team Athletes actually never use this source fully in their sport.
3 Aerobic system - gives energy true the use of oxygen, this system is technically unlimited available, provided we get sufficient fluids and nutrients during our exercise/work.
1 Feels like maximum effort, strength will quickly disappear after a few seconds. We all know the feeling of doing a sprint or lifting something really heavy. After you stop the discomfort very quickly disappears.
2 this system is not known by everybody, because it is very tough/unpleasant if you fully utilize it. Your muscles burn and almost feel crippled due to the large quantity of waste in the blood, and your breath is completely disorganized. Examples of using this system to the max are 1000/1500 meter skaters, 400/800 runners, 100/200 meter swimmers. Throwing up afterwards is not uncommon.   Layman people often think and say, why doesn't he keep going? That other guy sprints away from him and he almost stops? Well, those people don't know this system from experience. If you use it, you’re done and just cannot go further anymore. No matter how much willpower you have.
3 This system we all know, after all we use it our whole lifetime ;-). If you use it at max it lasts about 15 minutes, then you either have to stop or switch to a slower pace. At a slower pace you can almost use this unlimited.
Now point two: the difference between muscle fiber types
Roughly speaking, we humans have two types of muscle fibers in our muscles, slow (red), who mainly work on oxygen and fast ones (white) those work mostly without oxygen, using directly stored energy in the muscles (anaerobic energy). This is not entirely correct; there are also hybrid fibers that use both. For convenience, I leave that out of consideration for now.
Someone with lots of slow muscle fibers is a relatively good endurance athlete, but is a weak sprinter and a slow starter, someone with lots of fast muscle fibers is relatively a good sprinter, but for endurance work not so good. This is mainly inherited, exercise can change that a little, but a real sprinter always stays a sprinter, the same goes for an endurance athlete.
Now I come back to the question why one athlete still has a final sprint left and the other doesn't. Sprinters have a lot of anaerobic energy they can use, they can easily start quickly, but after this first burst they are spent. They use a lot of anaerobic energy, so when that is used they have to continue on aerobic energy but they don't have the right muscle type for that. For example, in speed skating you almost always see fast starters on the 1000/1500 having a slow last round.
Also we see in general that in sports events between 30 seconds and 2 minutes duration nobody can accelerate at the end. At best they can reasonably maintain their speed, real sprinters even can't do that once they have used their anaerobic energy they are spent.
Then you have the longer distances; say anything over 3-4 minutes. Well-trained athletes often have a sprint at the end of this. This is because on longer distances the start is relative slow and a reserve amount of anaerobic energy is left in the muscle. Even when we're really tired, is it still possible to have a final sprint, especially athletes who are able to hold back a bit in the first part of their race. These are athletes with a good mix of both fast and slow muscle fibers.
Real endurance athletes never have a sprint, which you often see at athletic events over 5 or 10 km, where it is often seen that athletes who run in front for laps are blown away completely in the final two rounds. They can only win if they shake off the competition before the end of the race. 
Sprinters also have, and this might sound a bit strange, no final sprint, before the finish line is reached they are out of their energy and not able to sprint anymore.
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