Understanding the Oxidative Energy System and How to Properly Feed It

http://breakingmuscle.com/nutrition/understanding-the-oxidative-energy-system-and-how-to-properly-feed-it

Kevin Cann

In previous articles I discussed the fueling of two of our energy systems - our ATP-PC systemas well as glycolysis. In the final installment of this series, we are going to dive into fueling the oxidative system. This is our primary source of ATP at rest and during longer duration physical activity. Understanding this energy system and how to fuel it can help increase performance in endurance events.

Enough Calories for the Oxidative System

The oxidative system is also known as the Krebs cycle and the citric acid cycle. In this system, carbohydrates and fats are the primary energy sources converted into ATP and this process takes place in the mitochondria of the cell. Protein is typically not utilized during this energy system except during bouts of exercise greater than ninety minutes and during starvation.¹ This means it is critical to be taking in enough calories of carbohydrates and fats to fuel endurance activity.

Low calorie eating and long, slow distance running are common amongst individuals attempting to lose weight. During these bouts of starvation or prolonged exercise we will use our protein to fuel activity. Our greatest source of protein in the human body is our muscle tissue. If you do not eat enough or work out too much, you run the risk of burning up muscle tissue for energy. This process is known as gluconeogenesis.

Too few calories from under eating or from over exercising can also lead to weight gain. Going too low in calories can decrease our thyroid hormone T3 by as much as 66%.² This puts our body into an energy conservation mode and can make weight loss extremely difficult. Having adequate fats and carbohydrates in the diet can help avoid these negative situations.

Carbohydrates and Fats

At rest, fats contribute 70% to energy needs and carbohydrates about 30%. As we learned from previous articles, as intensity increases we shift to using more carbohydrates for energy. As the activity becomes longer in duration (more than three minutes), we shift to using fats as the primary source of energy. The key to this transition is the amount of oxygen present in the blood.

If we have enough oxygen present in the blood, then pyruvate, the end product of glycolysis, is shuttled to the mitochondria and we enter the oxidative energy system. In this process we get six molecules of NAHD and two molecules of FADH2. These substrates are then brought through the electron transport chain where they are used to convert ADP into ATP. This process is known as oxidative phosphorylation. This yields us approximately 38 ATP from one molecule of glucose. This is a much higher energy yield than the other two energy systems.

Our stored fat can also be utilized in the oxidative system. Free fatty acids can be broken down into acetyl-CoA and hydrogen. The acetyl-CoA enters the Krebs cycle and the hydrogen atoms are brought through the electron transport chain and ATP is produced. A limiting factor of all this is oxygen uptake.

The Importance of Oxygen

Oxygen uptake is literally a person’s ability to take in and use oxygen. The beginning of all activity is anaerobic, or without oxygen. This is roughly the first three minutes of activity. After this three minute period we are left with what is known as an oxygen deficit. This is why we continue to breathe heavily once we stop our activity. We need to replenish the oxygen debt. Remember that enough oxygen being present is what allows us to utilize our long duration energy system. Once the oxygen deficit becomes too high, we will continue to utilize anaerobic mechanisms to fuel activity and blood lactate concentrations will raise and cause fatigue.

This is why it is important to train in all energy systems. Training long, slow distance can help us build an aerobic base and help strengthen this oxidative system by increasing your VO2 max, which is our ability to utilize the oxygen we take in. Interval training can help us recover by increasing our body’s ability to decrease blood lactate levels as well as making us more proficient at replenishing our oxygen debt.

Ketone Bodies

Another form of usable fats for energy are ketone bodies. Ketone bodies can be found in medium chain triglyceride fats. These are unique because they do not require bile salts for digestion. Instead they are shuttled to the liver, converted to ketones, and immediately used by cells. Research has been done on the use of ketone bodies in endurance training.

Depletion of muscle glycogen, our stored sugar reserves, leads to fatigue. Some research suggests supplementation with medium chain triglycerides can stave off fatigue by sparing our stored glycogen.³ This is most likely due to the easy nature in which medium chain triglycerides are converted to usable energy. Medium chain triglycerides can be supplemented in the diet by using MCT oil or by cooking more with coconut oil. Half of the fats in coconut oil are medium chain triglycerides. The evidence in the literature is contradictory on the use of medium chain triglycerides, but I have seen it work for a number of clients.

In conclusion, if we are working out for short term, high intensity bouts we need to make sure we ingest enough carbohydrates to fuel activity and to replenish our stored glycogen for recovery. As we exercise longer there is a shift to utilizing fats as a primary source of energy. Making sure we are getting enough fats in our diet to fuel longer duration activity can help improve performance. Also, adding medium chain triglycerides to the diet may help spare stored glycogen due to the easy conversion to usable energy in the form of ketones. It is important to keep in mind that not everyone is the same. Some people do well higher carb and others do well higher fat. Planning the best diet for you and your performance will take some tinkering around, but at least now with an understanding of how our energy systems work you can have a good starting point.

References:

1. Thomas Baechle and Roger Earle. Essentials of Strength Training and Conditioning. Human Kinetics (2008).

2. Wadden, TA et al., Effects of very low calorie diet on weight, thyroid hormones, and mood. International Journal of Obesity (1990). Accessed on October 11, 2013. 

3. Van Zyl, CG et al., Effects of medium-chain triglyceride ingestion on fuel metabolism and cycling performance. Journal of Applied Physiology (1996). Accessed on October 11, 2013. 

Krebs cycle graphic by RegisFrey (Own work) [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons.

Energy pathways chart property of Breaking Muscle.

Other photos courtesy of Shutterstock.

Understanding Energy Systems: ATP-PC, Glycolytic, and Oxidative, Oh My!

http://breakingmuscle.com/health-medicine/understanding-energy-systems-atp-pc-glycolytic-and-oxidative-oh-my

Tom Kelso

Human bioenergetics is an interesting topic. However, energy systems function is understood by few and/or can be confusing to many. Open a quality exercise physiology text and it can leave you saying “huh?” when reading about aerobic, anaerobic, and immediate energy metabolism. It can get even worse when sifting through all the biochemical processes.

Is it important to be able to explain the chemical breakdown of the oxidative Krebs cycle or anaerobic glycolysis if you’re a coach or an athlete in training? Not really.However, knowing the basics of how we generate energy can be helpful in understanding how we fatigue and what training measures can be used to minimize it. Let’s get going as simply as possible. I will do my best, but some “high-tech” discussion is necessary.

The first thing to remember is that ANY muscle contraction/force exertion is due to a molecule called adenosine triphosphate (ATP). When an ATP molecule is combined with water the last of three phosphate groups splits apart and produces energy. This breakdown of ATP for muscle contraction results in adenosine diphosphate (ADP). The limited stores of ATP must be replenished for work to continue; so chemical reactions add a phosphate group back to ADP to make ATP.

How ATP Is Produced

Take three different activities and put them on a continuum. On one end would be a quick, explosive burst such as throwing a punch. On the other end would be an extended, lower-level event such as walking five miles. Between the two could be anything: an intense twenty-second activity, one minute of constant force exertion, or a five-minute event with varied intensities of effort.

As you can see, there are many expressions of energy output depending on the amount of force required and the length of the activity. What then, is the energy source for activities that fall on the continuum at various points? This is the essence of bioenergetics - so many possibilities and so many factors involved.

The Three Energy Systems

Conventionally, there are three energy systems that produce ATP: ATP-PC (high power, short duration), glycolytic (moderate power/short duration), and oxidative (low power/long duration). All are available and “turn on” at the outset of any activity. What dictates which one (or two) is relied upon the most is the effort required.

Take home point: ATP must be present for muscles to contract. It can be produced via the ATP-PC system, the glycolytic system, or the oxidative system. If depleted, it must be replenished if further muscle contraction is to continue.

Perform an explosive, one-time movement such as a standing long jump or vertical jump and you exert maximal effort, but guess what? You will not become fatigued from this single exertion. However, jump multiple times and eventually you will become fatigued. Going all-out for as long as possible will deplete immediate ATP stores, then glycolytic stores. Continuing effort must be fueled by the oxidative system at a lower intensity, all other factors being equal. The most pure aerobic activity that exists is sleeping or lying comatose.

The ATP-PC Energy System – High Power/Short Duration

ATP and phosphocreatine (PC) compose the ATP-PC system, also sometimes called the Phosphogen system. It is immediate and functions without oxygen. It allows for up to approximately 12 seconds (+ or -) of maximum effort. During the first few seconds of any activity, stored ATP supplies the energy. For a few more seconds beyond that, PC cushions the decline of ATP until there is a shift to another energy system.It is estimated the ATP-PC system can create energy at approximately 36 calories minute.

Examples: a short sprint, lifting a heavy resistance for three repetitions, or pitching a baseball.

The Glycolytic System – Moderate Power/Moderate Duration

Now it becomes more complicated as energy demands shift to this system. The glycolytic system is the “next in line” tool after the ATP-PC system runs its course. Dietary carbohydrates supply glucose that circulates in the blood or is stored as glycogen in the muscles and the liver. Blood glucose and/or or stored glycogen is broken down to create ATP through the process of glycolysis. Like the ATP-PC system, oxygen is not required for the actual process of glycolysis (but it does play a role with the byproduct of glycolysis: pyruvic acid). It is estimated glycolysis can create energy at approximately 16 calories per minute.

Here is where it gets interesting. After maximum power declines around 12 seconds, further intense activity up to approximately 30 seconds results in lactic acid accumulation, a decrease in power, and consequent muscle fatigue. This high, extended effort is labeled “fast” glycolysis. Exerting further effort up to approximately 50 seconds results in another drop in power due to the shift in dependence on the oxidative system. Bottom line: it is getting tougher.

Example: think of an all-out sprint, to a slower jog, to an eventual walk. That is the progression of the three energy systems when going all-out.

Enter “slow” glycolysis into the discussion (warning: more science jargon ahead, but hang in there). Recall the byproduct of glycolysis is pyruvic acid. In fast glycolysis, more power can be generated, but pyruvic acid is converted to lactic acid and fatigue ensues quickly.Slow glycolysis is different. Relatively less power is generated, but pyruvic acid is converted to acetyl coenzyme A (acA), fed through the oxidative Krebs cycle, more ATP is produced, and fatigued is delayed. Thus, extreme fatigue can be avoided (but relatively less-intense effort can continue to be expressed) in slow glycolysis as compared to fast glycolysis.

Examples: any moderately-long runs such as 200-400 yards, a 1:30 effort of all-out MMA maneuvers, or a one-minute full-court press - offense display - and another full-court press effort in basketball.

The Oxidative System – Low Power/Long Duration

Your maximal effort was fueled initially by the ATP-PC, but your performance declines. Continued effort results in further decline, either via fast glycolysis (quick decline) or slow glycolysis (slower decline). You’re now entering the complex world of the low power but longer duration oxidative system, which is estimated to create approximately 10 calories per minute.

Examples: 6-mile run, low-level manual labor on an eight-hour work shift, or a 3-mile walk.

The effort demand is low, but ATP in this system can be produced three ways:

1. Krebs cycle
2. Electron Transport Chain
3. Beta Oxidation.

Let me explain the science, and then I’ll get back to you in plain English. The Krebs cycle is a sequence of chemical reactions that continues to oxidize the glucose that was initiated during glycolysis. Remember the acA? It enters the Krebs cycle, is broken down in to carbon dioxide and hydrogen, and “poof” two more ATP molecules are formed.

Here is the problem: the hydrogen produced in the Kreb’s cycle and during glycolysis causes the muscle to become too acidic if not tended to. To alleviate this, hydrogen combines with the enzymes NAD and FAD and is sent to the electron transport chain. Through more chemical reactions in the electron transport chain, hydrogen combines with oxygen, water is produced, and acidity is prevented.Notice this takes time due to the need of oxygen, which is why the oxidative energy takes a while and intensity of effort declines (i.e., all-out sprinting becomes slow jogging/walking).

The Krebs cycle and the electron transport chain metabolize triglycerides (stored fat) and carbohydrates to produce ATP. The breakdown of triglycerides is called lipolysis. The byproducts of lipolysis are glycerol and free fatty acids. However, before free fatty acids can enter the Krebs cycle they must enter the process of beta oxidation where a series of chemical reactions downgrades them to acA and hydrogen. The acA now enters the Krebs cycle and fat is metabolized just like carbohydrates.

In Plain English:

Due to the time-line, the oxidative system provides energy much more slowly than the other two systems, but has an almost unlimited supply (in your adipose sites - yeah, that stuff you can pinch!). The oxidative system by itself is used primarily during complete rest and low-intensity activity. It can produce ATP through either fat (fatty acids) or carbohydrate (glucose).

Because fatty acids take more time to breakdown than glucose, more oxygen is needed for complete combustion. If efforts are intense and the cardiovascular system cannot supply oxygen quickly enough, carbohydrate must produce ATP. However, in very long duration activities (i.e., marathons), carbohydrates can become depleted and the body looks to fat as the energy producer.

A Few Words on Protein

In extended activities protein can be used as a “last resort” for energy production (in rare cases where carbohydrates are depleted and stored fat is minimal). In such cases, it can supply as much as 18% of total energy requirements. The building blocks of protein - amino acids - can be either converted into glucose (via gluconeogenisis) or other sources used in the Krebs cycle, such as acA. But understand protein cannot supply energy at the same rate as carbohydrates and fats, thus it’s basically a non-issue).

Programming for the Energy Systems

It is estimated that the ATP-PC and glycolytic systems can be improved up to 20% and the oxidative system by a whopping 50% (but in untrained subjects only). Regardless, sport-specific conditioning plans and optimal nutritional intake need to be implemented. But be aware of the reality of genetics: your unalterable muscle fiber composition plays a huge role. If you possess predominately slow type I fibers (endurance) or fast type II fibers (strength), you can only do so much. For me, this explains why I never got a sniff of any national-level competitions back in the early 1980s.

What else can you do to maximize each energy system? I will provide specific recommendations in a forthcoming article. Stay in touch.

Understanding Glycolysis: What It Is and How to Feed It

 http://breakingmuscle.com/health-medicine/understanding-glycolysis-what-it-is-and-how-to-feed-it

Kevin Cann

In a previous article I explained the first of three energy systems, our ATP-PC system. In this article I would like to dive into glycolysis. Glycolysis takes over as the main energy system in activities that are slightly longer in duration and have a smaller energy demand than our ATP-PC system. Many of us train in this pathway and many sports require a high demand of the glycolytic pathway for fuel. Understanding the system and substrates involved can help increase you performance in these areas.

Glycolysis is the breakdown of carbohydrates. It lasts from roughly ten seconds into physical activity up to about two to three minutes. The energy for glycolysis comes from glucose, or our stored form of glucose - glycogen. Glycogen is stored in muscle tissue and the liver, and the average person holds about 1,500-2,000 calories of stored glycogen. Broken down there are about 100g of glycogen in the liver and upwards of 400g of stored glycogen in muscle tissue.

Glycogen in the Liver and Muscles

Storing glycogen in the liver and muscles serves an important function in human metabolism. Our liver is the organ responsible for controlling blood sugar between meals. When insulinlevels fall, the opposing hormone, glucagon, is released. Glucagon stimulates the liver to release some of its stored glycogen into the blood to maintain blood sugar levels.

Glycogen stored in the muscle tissue serves an important role as well. Our muscles main function is to move bones. This allows us to do all the locomotive tasks associated with daily living. What better place to store energy then within the tissues that require this energy to move us around? After the first seven to ten seconds of moving we utilize this glycolytic pathway for energy.

The first ten seconds of activity utilizes the ATP readily available in the cytosol of our cells. After that timeframe our body needs to resynthesize ATP from glucose and our stored glycogen. This process requires quite a few chemical reactions. Due to the increase in reactions, this energy system takes longer to kick in then the ATP-PC system, but it will be able to supply a higher amount of total energy.

Fast Glycolysis and Slow Glycolysis

Glycolysis can be broken up into two different parts - fast glycolysis and slow glycolysis. The determining factor is the direction in which the end product, pyruvate, goes. Within fast glycolysis the pyruvate is converted into lactate. With lactate our body can resynthesize ATP at a much faster rate. This would occur when the activity requires a higher energy demand.

Pyruvate on the left, lactate on the right.

In slow glycolysis the pyruvate is shuttled to our mitochondria and we enter the citric acid cycle, or the oxidative system. In the oxidative system the resynthesis of ATP happens at a much slower rate, but we can maximize the number of ATPs produced, yielding us with the highest amount of energy.

Lactate sometimes gets an undeserving bad wrap. Many people mistakenly associate an increase in lactate with an increase in lactic acid. However, lactic acid cannot exist when the body’s pH is around seven. Instead, exercise decreases the body’s pH and this is known as metabolic acidosis. In fact, lactate may actually be a buffer to this metabolic acidosis.¹Lactate is actually utilized as energy by type 1 muscle fibers and cardiac muscle fibers.

With that said the body’s lactate levels are relatively low at rest and increase with an increase in physical activity. Byproducts of these reactions may be responsible for metabolic acidosis. A clearing of the lactate from the blood is therefore a return to homeostasis. This is one aspect we attempt to train during high intensity interval training.

With enough oxygen present in the mitochondria, the powerhouse of our cell, the pyruvate is converted is shuttled into the mitochondria with NADH, a byproduct of glycolysis, and then converted into acetyl CoA. This is the start of the oxidative metabolism, which we will cover, in my next article.

Glycolysis and Proper Nutrition

Glycolysis is an anaerobic metabolic pathway. The only macronutrient that can be synthesized into usable ATP under anaerobic conditions is carbohydrates. We need to make sure we take in enough carbohydrates to fuel glycolysis during activity. We also need to make sure we take in enough carbohydrates to keep our glycogen stores full. A reduction in muscle glycogen is associated with fatigue.²

This is where the importance of post-workout nutrition comes into play. Studies have shown an increase in glucose uptake by muscle tissue post workout.³ This makes carbohydrates an important piece of our post-workout recovery meal. Simple starch may be the best source of carbohydrates post workout because of their ability to raise blood sugar levels quickly. This can allow for faster uptake by muscle cells to recover. Fruit may even be a better option. Fructose gets immediately shoveled to our liver when ingested. Upon reaching the liver it is converted into glycogen to refill liver stores (it will not refill muscle stores because muscle cells do not contain a receptor for the GLUT5 transporter required to carry fructose). Under conditions of decreased liver glycogen, such as exercise, fruit may have the ability to resupply the liver faster. Sweet potatoes, white potatoes, yams, and even white rice are good additions to the post-workout meal.

Other vitamins such as vitamin A, B2, niacin, and pantothenic acid are important for energy metabolism. This puts a high emphasis on quality foods such as fruits and vegetables for high-level athletes. Foods such as these can be obtained throughout the day. In some cases supplementation may be necessary. Some athletes require such a large amount of nutrients that it becomes difficult to obtain from food alone. In these cases, supplementation would be warranted. Make sure to work with a healthcare practitioner to determine if supplementation is right for you. 

In conclusion, if you participate in sports or gym activities that require high energy outputs for two to three minutes, you need to make sure you are ingesting plenty of carbohydrates. This is to ensure our muscle glycogen stores stay full to keep fatigue away as well as to supply our body with the necessary fuel to perform. The carbohydrates can be ingested from fruit, which may replenish liver glycogen stores more rapidly, or other safe starches such as potatoes.

In my next article we will look at the oxidative system and see how the energy requirements and substrates differ.

References:

1. Robergs, RA, et al., Biochemistry of exercise-induced metabolic acidosis. American Journal of Physiology (2004). Accessed on September 30, 2013. 

2. Ortenblad, N et al., Muscle Glycogen Stores and Fatigue. Journal of Physiology (2013). Accessed on September 30, 2013.

3. Poehlman, Eric et al., Effects of resistance training and endurance training on insulin sensitivity in nonobese, young women: A controlled randomized trial. The Journal of Clinical Endocrinology and Metabolism (2000). Accessed on September 30, 2013. 

4. Thomas Baechle and Roger Earle. Essentials of Strength Training and Conditioning. Human Kinetics (2008).

Energy pathways chart property of Breaking Muscle.

Glucose metabolism by Mikael Häggström [Public domain], via Wikimedia Commons.

Pyruvate/Lactate by Yikrazuul (Own work) [Public domain], via Wikimedia Commons.

Photos courtesy of Shutterstock.

Why Everything You Know About Lactic Acid Might Be Wrong

http://breakingmuscle.com/strength-conditioning/why-everything-you-know-about-lactic-acid-might-be-wrong 

Tom Kelso

Admit it. For years you have blamed high-effort, short-term muscle fatigue on lactic acid accumulation. It’s all over exercise physiology texts and Internet sites. Lactic acid accumulation is the reason high-effort, short-term activities shut down the muscle activity sooner rather than later. Conventional wisdom, despite being based on antiquated research, does make sense. You work as hard as you can, lactic acid accumulates rapidly, you’re unable to oxidize it aerobically, your muscles then become acidic, and your effort deteriorates into a low-level effort or comes to a screeching halt.

This is a true scenario, but is lactic acid to blame? Here is an update on this belief and the new research that supports it.

High-effort activity that requires the process of glycolysis(breakdown of stored muscle glycogen to produce ATP) results in the formation of lactic acid (pictured to the right). However, lactic acid is immediately split into lactate and hydrogen and does not remain as itself in muscle tissue. Lactate and hydrogen each face a different consequence.   

Lactate may stay in the cells to be used as energy or move to active and inactive muscles and used as energy.The use of lactate as fuel within the muscle itself varies with how well a person’s endurance muscle fibers are trained aerobically. Lactate can also be sent to the brain and heart for fuel, or to the liver to be converted to glucose.

The function of your brain is critical. When exercising, your body needs to maintain a steady supply of glucose to the brain to remain operational. Ever wonder why you get light headed following intense work? Yep, a lack of glucose supply. By the way, the manufacturing of new glucose in the liver during exercise is called gluconeogenesis. Interestingly, lactate is the most important facilitator of this process.

Great, but what then creates muscle fatigue if it's not lactic acid accumulation?

Remember, glycolysis results in lactate and hydrogen formation. Hydrogen ion (H+) accumulation can increase muscle acidity, but most of it is buffered via the bicarbonate buffer system, then converted to water and carbon dioxide, and ultimately eliminated via expiration through the lungs. If the accumulation of lactate and hydrogen is extreme, some research evidence shows it may interfere with muscular contractions. However, recent evidence suggests this is questionable.

Come on, man! What then is the cause of muscle fatigue if not for lactic acid accumulation nor the aforementioned? Well, here is what scientists have concurred. Muscle fatigue at non-sustainable workloads seems to be a result of the accumulation of other metabolites such as inorganic phosphates along with the inability to maintain the rate and force of contraction via the loss of potassium from inside muscle cells.

So, lactic acid itself as a muscle fatigue expeditor is nonsense? Let's look at it another another way. Trainees or active humans obtain about one third of their total carbohydrate energy from lactate. The remainder is from circulating blood glucose and stored muscle glycogen. In order to burn lactate as fuel for muscles, you can either burn it directly or convert it to glucose and then burn it. In research on untrained subjects, about 75% of the lactate used was directly oxidized. In trained subjects, about 90% was directly oxidized. Trained subjects also burned more overall lactate. (So basically, it pays to be in shape.)

What does this mean? Endurance training stimulates the body to use more lactate and use it more efficiently. It was concluded in trained subjects that lactate is a preferred energy source over glucose. This spares glycogen stores, giving you more endurance.

Here are a few more tidbits to help clarify the issue:

When glucose is broken down through glycolysis the byproduct is pyruvate. Pyruvate can then be pushed into the Krebs cycle. This creates energy through the aerobic system or energy can be created via lactate. As you now know, lactate is not a waste product but a viable fuel source for continued muscle contraction. Converting pyruvate into lactate results in quicker energy production as opposed to the longer oxidative process.

How fast can pyruvate be converted into lactate? Recent research shows it's dependent on the availability of oxygen. More oxygen equates to more pyruvate oxidized even though the amount is small. Regardless, if you're in better shape, the glycolysis byproduct pyruvate can be converted to lactate and serve as future energy.

Lactate accumulation only occurs when its production is greater than its clearance.Here's an example for you. Pour water down a drain slowly. The water drains at the same rate as it is poured. Now, pour the water at a higher volume and a greater flow will compromise drain's ability to empty and the water level will rise in the reservoir.

Your body is similar to the aforementioned example. Lactate is cleared from the body by the liver, heart, brain, and muscles. Lactate produced by the large leg and back muscles can be used by other less active muscles such as the deltoids and abdominals. These less activated muscles - combined with oxygen intake - will convert lactate back to pyruvate to provide more fuel. Pyruvate can then be used aerobically in less taxed muscle or it can become recycled to support greater-demand contractions such as demanding lower-body exertions.

Finally, to be an efficient energy source for another muscle group, lactate or pyruvate must be converted into a more efficient form. Therefore, circulating blood lactate is filtered through the liver where it is ultimately converted back into pyruvate, then to glucose through the gluconeogenesis process. The newly-formed substrate can then be returned to the muscle as an immediate fuel source or stored as glycogen to be used at a later time.

So, what can you take from this discussion?Lactic acid is not the cause of muscle fatigue as has been the common thought for years. Muscle fatigue and consequent inefficiency is due to the accumulation of other metabolites such as inorganic phosphates and the inability to maintain the rate and force of contraction via the loss of potassium from inside muscle cells.

Lactate production from high effort exercise is a good thing. Lactate is actually a provider of more energy for muscle contraction. Lactate also creates fuel for the brain and heart and can be converted to glucose in the liver.

In the end, lactic acid is not the issue. Lactate is, and it's your pal!

References:

1. Lactate and Lactic Acid: Dispelling the Myths, www.cyclingnews.com.

2. H. Westerblad, J.D. Bruton, and J Lannergren, “The Effect of Intracellular pH on Contractile Function of Intact, Single Fibers of Mouse Muscle Declines with Increasing Temperature,” Journal of Physiology 500 (1997): 193-204.

3 Messonnier, Laurent A., Chi-An W. Emhoff, Jill A. Fattor, Michael A. Horning, Thomas J. Carlson, and George A. Brooks, “Lactate Kinetics at the Lactate Threshold in Trained and Untrained Men,” Journal of Applied Physiology 114 (2013): 1593-1602.

Lactic acid graphic courtesy of Shutterstock.

Glycolysis chart by Rozzychan [Public domain], via Wikimedia Commons.

Gluconeogenesis chart by Boumphreyfr (Own work) [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons.

Ostarol (MK-2866)

Ostarol (MK-2866) относится к САРМ-ам (SARM).

Ostarol (mk-2866)- селективные модуляторы андрогенных рецепторов. Разрабатывался для лечения мышечной атрофии и остеопороза.
Работает и исключителньно на мышечную и костную ткань , связывается с рецепторами на прямую , что делает препарат полностью безопасным. Легальный препарат. Нет побочных эфектов. Даёт прирост мышечной массы и силы. Прошёл клинические испытания.

Термин «селективные модуляторы андрогенных рецепторов» (selective androgen receptor modulator, SARM, САРМ) был предложен для обозначения синтетических агонистов андрогенов, связывающихся с андрогенными рецепторами с высокой степенью тканевой избирательности, созданных с целью предотвращения побочных эффектов, свойственных эндогенным андрогенам. К ним относятся такие препараты как бикалютамид и флютамид, а также новые соединения Андарин и Остарин (MK-2866), и ряд других.

В результате ежедневного приема всего лишь 3 мг производного арилпропионамида - Остарина - в течение 3 месяцев у добровольцев наряду с наращиванием мышечной массы на 1,4 кг наблюдали увеличение силовых качеств и выносливости без особых диет и физических нагрузок. При этом активизируются только андрогенные рецепторы в тканях-мишенях, таких как мускулы и кости, в то время как стимуляция рецепторов в других органах, например в простате, не затрагивается, или подавляется. Этот САРМ имеет малый период полувыведения у людей - 4 часа. Отмечено, что его прием не вызывает задержку воды в организме. Скорее всего, данный препарат будет использоваться спортсменами на заключительных этапах подготовки перед соревнованиями, например тяжелоатлетами и культуристами. В ближайшие годы можно ожидать, что Ostarine (МК-2866) станет очень широко распространенным допинговым препаратом.

Из-за селективной природы этого нестероидного соединения не наблюдаются побочные эффекты, характерные для гормональной заместительной терапии. Остарин обладает анаболическим эффектом, сравнимым с тестостероном. Селективные модуляторы андрогенных рецепторов действуют более селективно и обладают высокой биодоступностью, что открывает широкие перспективы для их клинического использования. Кроме того, эти соединения проявляют анаболическую активность, влияя на андрогенные рецепторы, ответственные за рост мышечных волокон, что приводит к росту мышечной массы и силы.

Так же Остарин был выдвинут в кандидаты для клинических исследований в качестве препарата для лечения мышечного истощения.

Остарин является великолепным дополнением к Вашему пептидному курсу.

ВНИМАНИЕ: при покупке Вы получаете исчерпывающую информацию и рекомендации по применению препарата. Мы поможем и объясним Вам, как получить максимум пользы от данного пептида.

Что такое Ostarol?

Ostarol является продуктом SARM. GTx разработала его для профилактики и лечения атрофии мышц. В настоящее время препарат проходит клинические испытания и в конечном итоге может выписываться по рецепту врача для профилактики кахексии, атрофии, и саркопении и гормоно- или Testoserone- терапии.

В химических исследованиях Ostarol относится к классу химических веществ, известных как SARMs или селективные модуляторы андрогенных рецепторов. SARMs производят избирательное анаболическое воздействие на определенные рецепторы андрогенов, исключая остальные, отсюда их название. По сравнению с тестостероном и другими анаболическими стероидами и прогормонами, преимуществом SARM, таких как (Ostarine) МК-2688 является то, что они не имеют андрогенной активности в не-скелетно-мышечной ткани.

Как это работает?
Селективные модуляторы андрогенных рецепторов (SARMs) связываются с рецепторами андрогенов и оказывают костную и (мышечную) анаболическую активность.

Активация рецептора андрогена
Связывание и активация рецептора андрогена изменяет экспрессию генов и увеличивает синтез белка и, следовательно увеличение мышц.
Таким образом, в сущности, Šarms такие как Ostarine активизируют рост мышц таким же образом, как стероиды, однако в отличие от тестостерона и других анаболических стероидов и прогормонов, SARMs (как нестероидные агенты) не дают эффекта на увеличение простаты и других вторичных половых органов.


Ostarol в частности, оказывает свое анаболическое воздействие на мышечные ткани почти исключительно. Таким образом, он не только представляет собой новый потенциальный вариант восстановления для широкого спектра заболеваний, вызывающих потерю мышечной массы (от возрастных до связанных с ВИЧ ,или связанных с раком), но также имеет огромный потенциал для наращивания мышечной массы для культуристов, занимающихся фитнесом и спортсменов, чтобы минимизировать атрофию во время периода восстановления после серьезной операции или в аналогичных ситуациях.

На сегодняшний день GTx уже оценил преимущества Ostarol в восьми клинических испытаниях с участием около 600 человек, включая три исследования эффективности. В течение четырех месяцев IIb фазы клинических испытаний зачислены 159 пациентов для изучения Основной цели - абсолютного увеличения общей мышечной массы тела по сравнению с плацебо и вторичной цели - функции мышц (увеличение силы) .

В конкретном применении к бодибилдингу, было заведено много дневников пользователей на различных форумах. Они использовали Ostarol в качестве вспомогательного средства для увеличения уровня мышечной массы и силы.


Поскольку Ostarol является наиболее анаболически-активным препаратом из доступных SARMs, его первым и основным назначением должно быть получение прироста мышечной массы.
В настоящее время успехи в прибавке абсолютного веса даже близко не сопоставимы со стероидами, такими как diannabol. Вы получите в результате применения «эксклюзивную» и абсолютную мышечную массу.
В связи с отсутствием побочных эффектов по сравнению со стероидами / прогормонами, период реабилитации не требуется, и почти вся масса, полученная на Ostarol сохраняется после завершения курса.

Дозы 25 мг за 4-6 недель являются наиболее распространенным протоколом для таких целей. За период 4-6 недель, как правило, наращивается до 6-8 фунтов или 3-4 кг чистой мышечной массы. И при этом вы не ощутите никаких побочных эффектов, сопутствующих другим анаболикам.


По нашему мнению, наряду с постоянной прибавкой в массе мышц для достижения Recomping-эффекта, Ostarol проявляет себя в полную силу.
Recomping-эффект обусловлен потерей жира и получением мышечной массы. Именно такого эффекта пытаются достичь абсолютно все атлеты. Но достичь такого эффекта, будучи новичком и без специальной подготовки крайне сложно.
На помощь придет Ostarol, который позволит даже новичку достичь долгожданного recomping-эффекта. Препарат высвободит калории из запасов жира и они напрямую попадут в мышечную ткань.
Многие испытывающие Ostarol сообщают, что даже при употреблении минимума калорий происходило снижение веса, сжигание жира и одновременно с этим - увеличение силы и мышечной массы!

Одним из наиболее важных факторов при формировании мышц является затрата времени. Когда вы пытаетесь достичь нескольких целей, это требует более длительного периода времени. Необходимые изменения произойдут не скоро и даже при приеме стероидов, перспектива останется долгосрочной . К тому же, длительный прием стероидов негативно сказывается на состоянии печени и ЖКТ.

Хотя Ostarol также принимается внутрь, он не так токсичен и не оказывает настолько губительного воздействия на печень, как это делают другие оральные стероиды / прогормоны. Поэтому он может применяться в периоде более длительном, чем стандартный 4-недельный период с вышеупомянутыми соединениями.

Дозировка в 12,5-25 мг в течение 4-8 недель обеспечит великолепные результаты Recomping-эффекта.
Диета также должна быть оптимизирована таким образом, чтобы объем калорий был чуть выше нормы, и 30% калорий должны поступать из растительной и белковой пищи, чтобы получить лучший эффект.


Неоспоримые преимущества

Ostarol имеет период полураспада около 24 часов и каждая доза принимается внутрь только один раз в день. Поэтому он является совершенно сбалансированной добавкой.

Стоит отметить, что анализ крови пользователей показал незначительное повышение в сыворотке уровня эстрадиола (который может быть одним из эффективных факторов при лечении сухожилий, связок и костей после травмы или болезни).
Такое повышение незначительно и не должно вызывать беспокойство.

При приеме курса Ostarol :
- отпадает необходимость в предварительном применении ягод боярышника.
- отпадает необходимость в приеме расторопши для печени, или поликозанола RYR для холестерина и т.д.
- высокая биологическая активность без существенного повреждения печени
- устойчивый психологический фон, сопровождаемый чувством благополучия, без агрессии, которая может сильно навредить в личной жизни
- отпадает необходимость в длительном реабилитационном периоде между циклами
Как видно из перечисленных пунктов – Ostarine действенен и экономен.

Ostarol (MK-2866) не вызывает дозозависимое снижение ЛПНП и уровня холестерина ЛПВП, со средним ЛПНП / ЛПВП для всех доз. Препарат попал в низкую категории риска даже для людей с сердечно-сосудистыми заболеваниями - следовательно, существует небольшое влияние на значения уровня холестерина.

Метаболит M1 Wich, вызывающий токсичность на этапе S4 (временные нарушения зрения) не присутствует в Ostarine.
Также в отличие от S4, Ostarine не обладает андрогенными свойствами вне мышечных тканей.

Производит анаболический эффект даже при таких низких дозах, как 3мг
Отлично подходит для увеличения силы
Отлично подходит для постоянного набора массы
Отлично подходит для формирования тела
Отлично подходит для выносливости
Активизирует способность восстановления
Полураспад около 24 часов – при необходимой дозировке 1 раз в день.

Знаете ли вы о лучшем препарате, чем Ostarol? Такого не существует!


Результаты анализов