• Author / Uploaded
• Grobel

• Categories
• Sangre
• Dióxido de carbono
• Hemoglobina
• Oxígeno
• Respiración

Citation preview

BUTEYKO BREATHING COURSE MANUAL A DVA N C E D B U T E Y KO I N S T I T U T E

by Drs. Eduard Reuvers

Foreword This Buteyko Course Manual will help you prepare for the Buteyko Breathing course and give you a better idea of what the course is about. Please read this manual before starting the course or on the very first day of the course. It contains important information to help you get started the best possible way. October 2018 Drs. Eduard Reuvers, Advanced Buteyko Institute www.advancedbuteyko.com

1

1. About the Buteyko Course The complete Buteyko Breathing course consists of seven teaching sessions with a Buteyko instructor over a period of 4 to 6 weeks. Before each session you’ll be given some homework to do to prepare for the session. During each session you’ll meet with your instructor in person or via a video calling app such as Skype, Facetime or Whatsapp to review your practice, solve any issues and receive additional guidance and instruction to raise your practice to a higher level. The course is customized depending on the suitability of the various Buteyko exercises for each person. After the seven teaching sessions you’ll have learned how to safely practice Buteyko Breathing at a gradually increasing level of skill and hopefully have achieved a great improvement in your breathing scores and overall health and a corresponding reduction in chronic disease symptoms. After the course your Buteyko instructor will still be available for regular ongoing sessions as needed, to help you improve your breathing further or maintain your progress.

Account Setup After you’ve finalized your signup for the course, your instructor will make an account for you to login to the app and website. You’ll receive an automated signup email from our website system when your account is made. This signup email contains your account email and password. When you have your login details, please: 1)

Download and login to the Advanced Buteyko app. You can get the app at www.advancedbuteyko.com/app.

2)

Fill in the online Buteyko form using the link in the signup email. Alternatively you can use this public link: www.advancedbuteyko.com/ form but do make sure to fill in your account email address correctly.

2

Preparation for the First Teaching Session A convenient time will be arranged to meet with your instructor for your first teaching session, either individually or in a group setting, on location or via Skype, Facetime or Whatsapp video. To prepare for your first Buteyko Breathing teaching session, we suggest you do level 1 two or three times (using the Advanced Buteyko app) and then to move up to level 2 and do that a few times also. So when you speak with your instructor, you will have done some Buteyko Breathing sessions already at level 1 and level 2. If level 1 didn’t go too well, it is best to do it a few times more before moving on to level 2. Only go to level 2 if you feel level 1 went quite allright. When you meet with your instructor, you’ll have opportunity to ask questions and will receive additional personalized instruction and guidance on level 1 and 2, before moving up to level 3.

Doing Your First Buteyko Session To do your first Buteyko Breathing session, just open the Advanced Buteyko app and press the START button with the selected level set at level 1. The audio instructions will then start playing automatically. Please follow the audio instructions to the best of your ability and remember to keep it easy.

Timing your Buteyko Exercise Sessions It’s best to do your Buteyko Breathing exercises on an empty stomach, so either before a meal or a few hours after a meal, rather than directly after a meal. We also recommend to spread out your sessions evenly over the day. So perhaps you could do one Buteyko session in the early morning before breakfast, perhaps another one in the late morning, then one before lunch, one in the late afternoon before dinner and the last one in the late evening before going to bed. You can change these suggested times as you wish, whatever works best for you is fine. There’s no need to be too strict about the precise times as long as you make sure

3

to do the actual sessions. During the initial 4 to 6 weeks of the course we strongly recommend you do three to five Buteyko sessions per day and to keep to the Buteyko guidelines (as explained in chapter 2) rather strictly if possible. After the course, you can go down to just doing one or two sessions per day to maintain your progress and be a bit more lax with the Buteyko guidelines as well. In the beginning of the course, a Buteyko session will take about 15 minutes from start to finish. After a few weeks, when you can do the more advanced levels, there will be some shorter levels as well, some of which take just 8 to 9 minutes.

Relaxed Effort In the Buteyko Breathing course we aim to gradually but strongly improve your breathing over time. Being disciplined and consistent in doing your daily Buteyko Breathing sessions will definitely help you reach impressive results. But don’t be too strict on yourself. Stay relaxed with an open & inquiring mind. It’s very important to stay in a balanced state of relaxed effort: staying relaxed while gently pushing your breathing to gradually higher levels. It’s all about building momentum and making gradual progress while being in a state of relaxation.

Getting Ready Before moving on the next chapter of this manual, please make sure you have now downloaded the Advanced Buteyko app, are logged in to the app and have filled out and submitted the online Buteyko form. You should be in touch with your instructor to setup the first teaching session and be ready to start doing your Buteyko homework sessions at level 1 & 2 diligently, starting today.

4

2. Course Guidelines Please follow these guidelines to get the most benefit from your Buteyko Breathing course. It's important to also understand the reasons for these guidelines, so if something isn’t clear to you, please do ask your instructor. Exceptions and adaptations of these guidelines can be made after consulting with your instructor. 1) During the course you'll attend regular teaching sessions with your instructor to review and improve your practice of the Buteyko Breathing exercises. During the teaching session your instructor will review your practice, give additional instruction and guidance and new homework assignments and Buteyko exercise levels for you to do. 2) Do the exercises following the instructions and inquire with your Buteyko Instructor for further clarification if needed. Do 3 to 5 Buteyko Breathing sessions per day during the coming month for best results. 4 or 5 sessions per day would be best and 3 is still allright. But doing just 1 or 2 sessions per day is not enough. Keep at least 2 hours between your sessions and avoid doing your sessions on a full stomach (directly after a meal). There are 61 Buteyko exercise levels and in general we recommend to raise your level once a day, doing each level at least 3 times before going up to the next level. 3) Breathe through the nose during all your activities (not through the mouth). Exceptions can be made after consulting with your instructor. The nose is specialized in breathing only while the mouth is also used for speaking and eating. Breathing through the nose is better in so many ways: it helps retain water from the air you exhale, helps cool the brain (like air-conditioning) and improves NO (nitric oxide) and CO2 (carbon dioxide) levels. Nasal breathing also makes you look more intelligent - you can test this by opening your mouth while looking in the mirror. In short, the mouth is great for speaking and eating but it’s not a healthy alternative to nasal breathing. 4) Keep your mouth closed during physical exercise: This improves

5

endurance and recovery. If you can’t manage doing your activity with mouth closed, it means your fitness level isn’t good enough for that activity. Take a break or continue your activity at an easier level. Do keep an open mind because there are activities where mouth breathing is recommended during certain stages. 5) Don’t sleep with your mouth open. If you find that your mouth is always dry when you wake up in the morning, you probably sleep with your mouth open. In that case we recommend to try to use a small piece of "3M Micropore" tape to help keep the mouth closed during sleep. When you first try using the tape, just use a very small piece of tape to keep your upper lip connected to the bottom lip. After you get used to it, you can try out a larger piece of tape horizontally covering the whole mouth. Take it slowly and play with it, do it step by step. 6) Avoid eating foods containing a lot of complex proteins, especially when combined with other foods. Foods such as chicken, duck, all seafoods, unboiled milk and young or unripened cheeses are quite difficult for the stomach to break down and they take a longer time to process. Your breathing will most likely be worse than usual after eating foods rich in complex proteins - and it will take a few hours for your breathing to recover to it’s usual values. These foods take a lot of energy to process and temporarily drain your energy. 7) Avoid overeating & keep your stomach feeling light. When eating, just stop eating if you're not really hungry any more. This will help improve your energy levels and enhance your progress made with Buteyko Breathing. 8) Vegetables and fruits are foods that complement your Buteyko Breathing practice very well. They are light and easy to break down and contain many healthy vitamins, enzymes and amino-acids your body needs to function well. They are an excellent replacement for food rich in complex proteins. 9) Avoid sleeping on your back. Intend to sleep on your stomach or the left or right side. Why? When you sleep on your back, your lungs experience very little resistance and will expand more, leading to the tendency to over-breathe during sleep. With Buteyko, we’d rather see you avoid over-breathing and sleeping on

6

your side will help. 10)

Make sure to have some natural sea salt at home. Sea salt helps your

body improve its electrolyte levels while your breathing is getting better. Specifically, sea salt prevent the occurrence of minor headaches, dizziness and/or exhaustion due to a low level of electrolytes during or directly after a Buteyko session. If you experience these symptoms during or after a Buteyko breathing session, take some sea salt and be sure to let your instructor know. Of all these guidelines, the most important ones are number 1 and 2: Be consistent and diligent in doing your daily Buteyko breathing exercises and attend the teaching sessions with your instructor.

7

3. Measure your Breathing In Buteyko Breathing, we measure the breath using the Easy Breath-hold (EBH, also called the Control Pause or CP). The Easy Breath-hold is explained in the level 1 exercise of our Advanced Buteyko app. You will also do the Easy Breath-hold together with your instructor during the first class of the Buteyko group course.

How to Measure The Easy Breath-hold measures how many seconds it takes before you experience the feeling of lack of air (very minor air-hunger) after starting a breath-hold after a normal exhalation. For consistent and accurate measurement, the Easy Breath-hold should be measured when sitting and at rest. It is extremely important not to push your measurement: It should always feel easy and without difficulty - that’s why we call it the Easy Breath-hold. If you notice the start of any difficulty, you should stop the Easy Breath-hold immediately. The most common error in Easy Breath-hold measurement is to push the score higher, beyond the first feeling of air-hunger. Please remember that the Easy Breath-hold is not a competition but a scientific measurement very much like measuring your pulse.

Meaning of the Easy Breath-hold Score The average modern person has an EBH of about 15 to 20 seconds. With a EBH of 20 seconds or lower, people are at high risk of developing serious chronic disease. With an EBH of less than 10 seconds, chronic diseases may become acutely life-threatening, requiring emergency care at the hospital. The ideal EBH is 60 seconds which indicates optimal breathing and very strong health. An EBH of 80 to 180 seconds indicates the breathing is extremely very well suited for high

8

performance by athletes. To learn more about the Easy Breath-hold (or Control Pause), watch the video at www.advancedbuteyko.com/videos#ebh

9

4. Breathe Less to Get More Oxygen Most people do believe that better breathing can lead to bringing more oxygen to your cells. Most people believe that if you breathe more, you’ll get more oxygen. And that if you breathe less, you’ll get less oxygen. The process by which the body brings oxygen from the lungs to cells is however more complicated than most people would think, and it’s a bit counter-intuitive as well, so most people misunderstand how it actually takes place. The real story is that for most people in most situations, if they want to deliver more oxygen to their cells, they need to learn how to breathe less. The key point to understand is that CO2 makes it easier for oxygen to be released from the blood by haemoglobin. Haemoglobin has a chemical bond with oxygen molecules and the strength of this bond is determined by the CO2 content of the blood. More CO2 in the blood lowers the strength of this bond between oxygen and haemoglobin. So if there is more CO2 in the blood, the haemoglobin will more oxygen to be used by cells. Oxygen supply to cells is not just dependent on how much oxygen we breathe in, but also on how much CO2 we breathe out. If we breathe out too much CO2, the CO2 content of our blood becomes dangerously low, inhibiting efficient oxygen distribution. Overbreathing causes the blood to be scrubbed clean of CO2, which negatively impacts the oxygen supply to your cells. Most people have the perception that oxygen is good (like God) while CO2 is evil (like the devil). But when we look at how our blood brings oxygen from the lungs to cells, it becomes clear that oxygen needs CO2 to be released from the blood in sufficient quantity. Oxygen and CO2 are really team players who work best in each others presence. The scientific formula that describes how CO2 causes haemoglobin to release more oxygen to cells is called the ‘Bohr Effect’ and it is an essential element of Buteyko Breathing theory. The expanded version of the Bohr Effect is called the ‘Buteyko Effect’ and it goes as follows:

10

In this formula, MVr is the Minute Breathing Volume at rest - it is simply how many liters of air we breathe per minute. If we breathe less liters of air per minute (MVr goes down), it causes the CO2 content of the blood to go up (PaCO2 rises). PaCO2 going up in turn leads to a decreasing strength of the chemical bond between haemoglobin (Hb) and oxygen (O2) which is called Hb-O2 affinity. And when this Hb-O2 affinity goes down, haemoblobin lets go of more oxygen so the oxygen content of venous blood goes down (SvO2) which causes the oxygen difference between arterial and venous blood (a-vO2 diff) to rise. This means that the oxygen supply and the oxygen consumption by cells (VO2) has gone up which leads to better health and fitness and a decrease in chronic disease symptoms. To learn more about the Buteyko Effect and the definitions of the terms used above, please read the online article on the Buteyko Effect at www.buteykoeffect.com/buteykoeffect.php.

11

5. Better CO2 Levels Carbon dioxide is the chief hormone of the entire body; it is the only one that is produced by every tissue and that probably acts on every organ. Yandell Henderson, Ph.D. - Cyclopedia of Medicine (1940)

When we breathe too much, we exhale too much CO2 and so the CO2 content in our lungs and blood goes down. Most people are not aware that CO2 has many important functions in the body - the most important being that CO2 plays an essential role in maintaining blood pH and delivering oxygen to all cells in the body. To illustrate the importance of healthy CO2 values of the blood, here’s a list of the health problems that will occur when CO2 levels are too low: 1.

Low CO2 content makes the bond between haemoglobin and oxygen too strong so that it is difficult for oxygen to leave the blood and body cells experience a lack of oxygen. The reason for this is that CO2 determines the strength of the bond between oxygen and haemoglobin (Hb-O2 Affinity). This effect is known as the Bohr effect or perhaps more accurately, the Verigo-Bohr Effect. It was first discovered in 1892 by the Russian scientist Bronislav Verigo, and later in 1904 again by the Danish scientist Christian Bohr (the father of Niels Bohr).

2.

The organism may compensate for the lack of oxygen supply caused by low CO2 by raising blood pressure and raising the heart beat. Higher blood pressure helps oxygen leave the blood more easily, while a higher heart beat pumps the blood around more quickly so more oxygen can be distributed. But these 2 compensation mechanisms create other problems on the long term...

3.

A drop in CO2 content of the blood immediately causes a change of blood pH into the alkaline direction. This change in blood pH negatively influences the activities of all 1000+ enzymes and vitamins. When the blood pH reaches 8 or higher, the organism dies. We need CO2 to maintain

12

a balanced blood pH, which works by using the bicarbonate buffering system of the blood. 4.

With low CO2 content, the airway passages and blood vessels constrict and become narrow. With higher CO2 content, these passages relax and increase in diameter, allowing for the improved flow of air and blood. CO2 acts as a relaxant for the smooth muscles of airway passages (bronchi) and blood vessels.

5.

A lack of CO2 negatively influences important metabolic processes that rely on CO2. For example, CO2 is required for the carboxylation of pyruvate and acetyl in the metabolic pathways of gluconeogenesis and lipogenesis. Also the synthesis of the essential aminoacid glucamine (and the non-essential asparagine) requires CO2 molecules. Many other biosynthetic reactions require the involvement of CO2 molecules and low CO2 levels makes it more difficult for them to take place. This will affect your energy-levels.

6.

Low CO2 levels increase the excitability of the nervous system. Smaller and subtle stimuli can then easily cause a big reaction by the nervous system, causing the nervous system to enter a state of permanent excitement characterized by high stress, low relaxation and low ability to focus (ADHD).

7.

Low CO2 content worsens brain function and intellect. For neurons to synapse with brain cells in an orderly and efficient manner, an ideal level of CO2 is needed. A lack of CO2 makes communication between brain cells more erratic and thus lowers your IQ and EQ.

8.

Low CO2 levels cause an increase in respiratory center excitability. This means that your breathing will respond very quickly and strongly to an increase in physical activity, making you quickly feel exhausted and out of breath. With high CO2 levels, your respiratory center will allow the breathing to stay more normal during exercise, so you can do more exercise without feeling out of breath.

9.

Low CO2 content causes decreased uptake of glucose from the blood and raises your blood sugar levels. The rate and efficiency in which sugar is

13

delivered to cells is regulated by the level of carbon dioxide. If CO2 levels are optimal, sugar can be burned more quickly and blood sugar levels are more stable. 10. A low CO2 level also weakens your immune system by lowering the antibody-antigen affinity. This means that it becomes more difficult for your antibodies to attach to and disable viruses and bacteria. To learn more about CO2, we recommend you to read Yandell Henderson’s full article available at www.advancedbuteyko.com/CO2

14

6. Breathing Health Zones In Buteyko Breathing, the Easy Breath-hold (EBH) is the main indicator of your breathing and general health. If your EBH is 60 seconds, you’re in a state of optimal health according to Professor Buteyko. But if your EBH is lower than 60, your health is in a state of weakness and chronic disease. The extent to which chronic disease actually manifests depends on the duration of your EBH. With a EBH of about 40 to 50 seconds , you likely won’t really notice serious symptoms of chronic diseases. But as the EBH goes down to 5 or 10 you will surely notice various chronic disease symptoms arising and getting stronger, simply due to having a low EBH which implies worsening oxygen distribution and low blood CO2 values. The table below describes how specific EBH values relate to your breathing pattern, the CO2 content of the air deep in your lungs and your general health status. For example: the breathing of a person with an EBH of 20 seconds (in the grey column) can be described as hyperventilation. This person breathes approximately 10.5 liters air per minute while this would optimally be 3.5 liters air per minute (with a EBH of 60). With a EBH of 20 seconds you are breathing an amount of air equal to what 3 people with an EBH of 60 seconds breathe: It’s simply way too much.

15

16

7. Nitric Oxide Nitric oxide (NO) is a gas which promotes fitness and health which is produced by our own bodies in the lining of the arteries and in the nasal passages. Nitric oxide (NO) is not to be confused with nitrous oxide (N2O) which is better known as ‘laughing gas’.

Important functions of Nitric Oxide in the body 1)

Nitric oxide is a powerful vasodilator. This means it relaxes blood vessels, lowering blood-pressure and the heart rate and thus protect organs such as the liver from damage due to a restricted blood supply.

2)

Nitric oxide helps improve communication between nerve cells in the brain.

3)

Nitric oxide assists the immune system at fighting off bacteria and viruses.

4)

Nitric oxide reduces inflammation.

5)

Nitric oxide improves sleep quality.

6)

Nitric oxide increases strength and endurance.

The 1998 Nobel Prize was awarded to the discovery of the role of nitric oxide as an important cardiovascular signaling molecule. When we breathe through the mouth, we don’t benefit from the nitric oxide produced and present in our nasal passages. By breathing through the nose, we enrich the inhaled air with nitric oxide in our nasal passages which will then enter the blood so we’ll receive the many health benefits. So make sure to always keep breathing through the nose unless you have a very good reason not to!

17

8. The Buteyko Exercise Levels During the course, course participants use the Advanced Buteyko app to do and learn the Buteyko exercises. The Advanced Buteyko app contains 61 Buteyko Breathing exercises, arranged by level. You’ll start at level 1 and as you gain experience and learn valuable skills, your instructor will open up additional levels for you to do to make your Buteyko practice more powerful and advanced and reach better results. In general, we recommend course participants to raise their level once a day. So if you start at level 1 on day 1, you’d raise your level to level 2 on day 2, after doing level 1 three or four times on the first day. This way, you’ll slowly raise your level day by day. If your progress is smooth, you’ll be doing the advanced level Buteyko exercises (at level 13 and higher) after about 13 days. You’ll also have regular teaching sessions with your personal Buteyko instructor so you can be confident to have a good foundation in the practice and to apply the Buteyko techniques in a way which is suitable and works best for you. You won’t need to learn all levels. Your instructor will pick the ones most suitable for you. The first 13 levels are the learning levels, where raising your level means your practice is becoming more advanced and powerful. After level 13 you’ll gain access to the many advanced levels that provide alternative ways to practice. There are a number of specialized levels such as meditation, walking, recovery, nose clearing, etc. Some of the levels are quite long and take up to an hour while others are very short and take just 5 minutes. We encourage our students to try out various levels and do the ones they like most and give best results. Not all levels are suitable for everybody and your instructor will provide you with guidance on the best levels for you to use.

18

9. Cleansing & Detox As your breathing becomes better and your Buteyko Breathing scores improve, all body systems become stronger: respiratory system, metabolic system, immune system, nervous system, digestive system, cardiovascular system, endocrine system, muscular system, etc. As the body gains in strength and health, three cleansing and detox processes often occur: 1)

Autophagy is where individual cells start recycling broken molecules (proteins, amino-acids, etc) that are stored in the garbage-collectors in each individual cell. This is a very good sign of increasing health: the body really starts a deep clean.

2)

The body will also start removing toxic substances that were originally stored in fat cells to get the out of the way and keep them out of the bloodstream where they can do a lot of damage. When the toxins are again removed from the fat cells, they will need to really be processed, broken down and disposed through urine, feces, sweat, breath etc.

3)

As the immune system becomes stronger, it starts to seek for hidden viruses more actively and intensively. When it encounters a virus in for example the throat, urinary tract or somewhere else, the traditional symptoms of flu, fever, pain or infection may arise while the immune system is eradicating the virus. This usually happens after a solid improvement in your breathing scores (breaking your personal record). Often big improvement in scores will be followed by temporary symptoms of fever or cold and the corresponding reduction in wellness and breathing scores.

These processes are how the body gains health through cleaning up on the cellular level and by removing toxins, viruses and infections from the system. Symptoms can become acute before they disappear. Detox and cleansing are

19

often a positive sign as your health will be stronger afterwards. It's very important to keep us informed so we can help solve complications.

20

10. Medication If you take any medications to treat chronic disease symptoms, we often see that as the breathing improves, your chronic disease symptoms will lessen which will eventually reduce your need for medication. So when after a few days, weeks or months of Buteyko Breathing your health and symptoms have improved significantly, you may find your usual dosage of medication is too strong. When this happens, please visit your doctor and tell him about the symptomatic improvements you’ve been experiencing and ask if it may be suitable to adjust your medication? Also do keep us informed of any big changes in medication taken during the course, as this may affect your Buteyko Breathing practice and scores.

21

11. Making Progress When doing the Buteyko Breathing course, progress can show in different ways: Buteyko breathing scores are going up. Chronic disease symptoms are improving. Feeling more energetic, healthy, balanced & stronger in general. Experiencing the typical detox and cleansing symptoms. Experiencing a reduced need for medications. Some course participants are able to smoothly improve their breathing in less than 2 months from a CP of 12 to more than 40 (view chart on the next page) and experience strong health benefits and strong improvements in chronic disease symptoms. For other course participants however the path may be different, with obvious improvements in some areas while in other areas progress may - for the time being - seem elusive. The point here is that we cannot choose which kind of progress we will experience in what time period. All we can do is keep doing the daily breathing exercises. Sometimes we just need to be patient and steady and give our body some time to adjust so our scores can go up further. At other times however we may benefit a lot from changing the approach or choosing another Buteyko level to continue our practice with. It’s your instructor’s job to recognize what’s happening and select a suitable response.

22

The chart above is an example chart showing the excellent progress made by one of our course participants. Their Easy Breath-hold time (or Control Pause) went up from about 12 to over 40 seconds in less than 2 months. This increase in breathing scores was accompanied by a complete 100% reversal of all asthma symptoms.

23

12. Stay in Touch When you experience any issues or sudden changes in breathing or health during or after the course, please get in touch with us immediately.

Sudden Changes in Breathing If you experience a sudden rise or drop in breathing scores, do inform your Buteyko Breathing instructor of your current situation. Sudden changes in your breathing scores can indicate that your Buteyko Breathing practice needs to be adjusted to ensure smooth progress. The sooner the adjustment is made, the better.

Lack of Progress If you don't observe satisfactory growth in scores nor an improvement in chronic disease symptoms or general wellness and energy level, do inform your instructor so they can have a more detailed look at what exactly is going on.

Changes in Disease Symptoms If you experience a sudden worsening or improvement of your chronic disease symptoms, do inform your Buteyko Breathing instructor. Sudden changes in symptoms can be related to your Buteyko Breathing practice.

Changes in Medication If your doctor prescribes new medications or changes your medication dosages please also inform your Buteyko Breathing instructor of this change.

24

13. Recommended Videos There’s a very interesting BBC documentary on Buteyko Breathing (from 1998). It’s about 3 patients with very serious breathing problems, trying out Buteyko Breathing and seeing how it goes. The video gives a quick overview on Buteyko Breathing theory and history and shows how effective Buteyko is when done well and with dedication. The documentary is a great introduction to Buteyko Breathing to share with family and friends. You can view the BBC documentary video at this link: www.advancedbuteyko.com/bbc. We also have some interesting Buteyko instructional videos at www.advancedbuteyko.com/video and an Australian TV broadcast on Buteyko (from 1993).

25

14. Advanced Buteyko App Visit www.advancedbuteyko.com/app to download our Advanced Buteyko app for iOS & Android or use the webapp instead. We do utilize the app in the Buteyko course. When you signup for the course, your instructor will make an account for you to login to the app & website.

26