Ok I’m assuming a few things here to save me a lot of time, if you want more info I’ll try to help when I get back but I’m sure someone else could defently help you out.
Lactate Shuttle – What is it and why is it important?
Process of the Lactate Shuttle is as follows…
- Pyruvate (pyruvic acid) is formed when glycogen and glucose are being broken down at high rates in your muscles (called glycolysis which is the conversion of these into pyruvate). Pyruvate is then converted to Lactate (lactic acid) as it increases in the muscles.
- Lactate is now formed and transported away from the muscle cells into surrounding tissue and blood. This allows glycolysis to persist and thus continuing the supply of energy to our muscles.
- The muscle cells which the lactate is transported to can cause the lactate to be broken down to fuel (mainly ATP) or can be used to build glycogen.
That is the Lactate shuttle basically, there are limiting factors on this process which contribute to the lactic threshold which we all have; they are…
- Oxidative energy systems
- Speed of transport of the lactate (MCT1 &4)
When pyruvate is formed in your muscle in excerise it is directly related to the work being done, as the intensity of the exercise increases the process of glycolysis also increases. This of course creates more Lactate (lactic shuttle), your body reaches a point where it can no longer deliver enough oxygen to the muscles to oxidise the lactate into energy and thus causes the lactate to start to collect in the blood. This point is called the Lactate threshold, of which another factor is important; the speed of transport of lactate from the blood to tissue.
Monocarboxylate transporter’s (MCT’s) are proteins found in muscle tissue of which two in particular relate to the transport of Lactate in the human body. These are MCT1 and MCT4; both seem to have different functions and are independent on one another. MCT1 are mainly found in Oxidative fibres (slow twitch) while MCT4 is found mainly in Fast twitch fibres. MCT1 is located in the mitochondria and sarcolemma (cell membranes of muscle cells). Both have different functions; MCT4 removes the lactic acid from the muscles while MCT1 can either accept or “give away” lactate from tissue, depending what is required by the muscle. The best thing about these is that they are highly responsive to muscle activity (which would be predicted seeing as they are responsible for the upkeep of the glycolysis process). This means you can readily train and improve the transportation system of your body and thus improve your lactic threshold.
Your lactic threshold is the point where the intensity of the exercise is causing the glycolysis process to produce lactate in excess of what you body is capable of transporting and oxidising to energy. This point see’s a sharp increase in the level of lactate in your blood and is noted as a % of your VO2max.
Lactate Threshold – How to train
Your lactate threshold is just as if not more important to train than your VO2 max, as it is a limiting factor in the energy available to your muscles. The higher the percentage of VO2 max your lactate threshold is the more intensity you can achieve in competition. The best thing is that your lactate threshold can be improved quickly and for your whole body, without separately training each part. This confused me to start with, but if you train one part of your body such as your legs the other regions of your body also respond in the same positive way to the training. So in effect of running you actually improve the energy system or your whole body, (even training on leg improves the ability of your other leg).
However this doesn’t mean go for hours and hours of run’s each day, the most efficient way to train your lactate threshold is to train above it. By doing this your body increases MCT’s and their efficiency, increasing the speed of the transportation of the lactate throughout the body. From what I have read it seems this may be the reason why High intensity training creates greater fat loss in humans, but that’s a whole different one. MCT’s and hence lactate transport play a large part in the way which you should train, in order to improve your lactate threshold. MCT4 does not respond to mild exercise, while MCT1 responds best to endurance exercises; therefore you should aim to target both of these in your workouts. Good ideas for quick improvements are high intensity workouts including; HIIT, Fartlek and Tabata intervals. Mix it up try doing this on your punching bag for a good workout.
Relating to Scrap’s Clues
Ok this is pretty much guess work on my behalf so please make your own conclusions.
Now this leads to relating with scrap’s clues that your heart work’s 35% better on your back and that with certain movements you can produce 30% less lactic acid (I’m assuming for the same work). Therefore I’m thinking that overall your body becomes much more efficient, you have a lower blood pressure and at few beats per minute while transporting the same amount of oxygen to your muscles to oxidise the lactate. With 30% less lactate produced your lactate threshold will be artificially increased as less lactate is required to be oxidised given the same level of oxygen, pushing the point where lactate required closer to VO2 max. This would cause your MCT’s to work more efficiently at each intensity as they are not being flooded by as much lactate as normal, causing them to transport the lactate to tissue which needs fuel the most; allowing your body to adapt to a reduction in fuel to achieve the same level of output. If this were done in such a way to reduce stress on your body you would be able to improve your lactic threshold with reduced risk of injury.
Let me know what you think guys and the conclusions I’ve made, don’t really know if they are right or not but its 2 am here and my mind is buzzing thinking of ways to be able to do this if I have understood it correctly. But I doubt I have so will wait for your feedback.
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