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  • Writer's pictureAnderson Petergeorge

The Science of Yoga: The Risks and Rewards – William J. Broard


Chapter: Health

Sub-Chapter Summary: Yoga has been scientifically proven to provide rejuvenating benefits such as decreased spinal deterioration, improved balance to prevent fatal injuries as we age, decreasing your biological age through telomerase levels. The breathwork done in yoga increases the oxygenation within your own body.

  • Yogis through breathing exercises work to better utilize the carbon dioxide and to efficiently bottle it up within the body

    • Carbon dioxide surprisingly helps oxygenate the body by allowing the hemoglobin in the body to release oxygen. Therefore better capturing carbon dioxide within the body helps increase oxygenation; Pranayama is a term for these breathing exercises

  • Slow breathing produces huge drops in the exhalation of carbon dioxide

    • The repetition of "om", the holy syllable of yoga, "materially diminished" the carbon loss within the body

    • Through studies, researchers found "fast breathing" does not increase the oxygen within one's body but controlled slow breathing and utilizing the carbon dioxide within one's body did

  • Inversion poses like the headstand and shoulderstand reverse the effects of gravity, invigorate the circulation and flood the vital organs and brain with nourishment, bringing about a sensation of rejuvenation

    • Yoga has allowed yogis to live on a reduced metabolism

  • In 2009, investigators at the University of Pennsylvania reported that twenty-six people who did Iyengar yoga for three months succeeded in reducing hypertension and its precursors

  • Yoga has scientifically been proven to slow the deterioration of the spine. Physicians in Taiwan reported on a study of thirty-six people. Half had been taught Hatha yoga for at least a decade and the other half were judged to be in good health. They were no differences in age or sex. When the spines were scanned the group of yogis had "significantly less" degenerative disease than the control group.

    • Studies believe this is because spinal flexing may have caused more nutrients to diffuse into the disks. Another possibility is the repeated tension and compression of the disks stimulated the production of growth factors that limited aging.

  • In 2002 immunologists at North Shore University Hospital reported yoga's remarkable improvement and control of the body's immune system, playing major roles in fighting inflammation.

  • Scientists have found that telomeres (DNA tips) get shorter each time a cell divides and thus serve as a kind of internal clock that determines the cell's allotted time in life. This discovery led to the 2009 Nobel Prize in Physiology/Medicine. For scientists, telomeres suggested a more accurate way of measuring biological age than just simply marking the passage of years.

    • A number of everyday conditions eroded telomeres - a main one being chronic psychological stress. Therefore reducing stress slows down your biological clock. Therefore stress reducing exercises like yoga can help extend your biological clock.

  • A Harvard-trained physician with his team looked at 24 men who did yoga for an hour a day, six days a week. Scientists assessed telomerase levels and other physical and psychological measures before they started and at the end of the 3 month program. Results were unambiguous, there were significant declines in cholesterol, blood pressures and importantly levels of telomerase that shot up by 30%

Chapter: Fit Perfection

Sub-Chapter Summary: Yoga provides various benefits to mood, psychology, flexibility and balance however provides limited growth and benefits to aerobic and cardiovascular gains. This signifies the need and benefits of cross training with various different methods of exercise (e.g. running/weight lifting in combination with yoga).

  • In exercise physiology and sports medicine peak oxygen consumption is known by VO2 Max, it is known across the globe as the single measure of cardiovascular fitness and aerobic power

    • V stands for Volume and O2 for oxygen

  • Regular aerobic training (e.g. running, swimming) turned out to increase the size of the heart

    • Cardiac output of elite athletes was about twice that of untrained individuals

    • Three months of endurance training could raise VO2 max between 15-30 percent. Two years raised it as much as 50 percent

  • In measuring what exercise produced the best cardiovascular workout in 1968, muscular activities such as calisthenics and weight lifting were the least effective.

    • Participants sports like golf and tennis came in second least effective

  • The activities that were the big winners were sports like running, swimming and cycling

    • Sports such as handball, squash and basketball also were measured to improve cardio

  • Scientists found that forceful exercise improved the performance of virtually every tissue in the human body. It produced new capillaries (tiny blood vessels) in skeletal muscles, the heart and the brain, increasing the flow of nutrients and the removal of toxins. It also raised the number of red blood cells, improving the transport of oxygen and also caused the walls of the blood cells to produce nitric oxide a relaxant that increases blood flow.

  • A study at Duke Medical University measured a sample group of 100 people with a third practicing Hatha yoga, a third riding a stationary bike and a third doing nothing for 4 months

    • The ones that rode the bike had a 12% increase in VO2 Max but the yoga group had no statistical change

    • However the yoga group as a whole were measured to feel better psychologically compared to the other groups

  • In yoga the Suyar Namaskar (Sun Salutation) is an aerobic yoga routine to help improve cardiovascular health however still does not compete to increase VO2 levels as aerobic exercises

    • Vinyasa - Vin "In a special way" and nyasa "to place"

  • "Yoga was designed for relaxation primarily. The more aerobic you make yoga, the less improvement you'll see in those areas."

Chapter: Moods

Sub-Chapter Summary: The relaxation that yoga provides after practice has been measured to provide long-term benefits to moods (e.g. prevents/reduces depression) but also can allow individuals to gain control of their automatic nervous system. Advanced yogis have been measured by scientists to be able control functions not seen as possible such as the temperature of their body, heart rate, adrenaline levels and blood flow through their practice.

  • Studies show how yoga poses can fine-tune the nervous system, reset the chemical balance in blood and help to relax muscles

  • Moods are considered less intense, more general, longer lasting and less likely to arise from a particular stimulus - drawn-out emotions

  • Joy over a period of time produces a happy mood and sadness over time results in depression

    • "A rich man in a bad mood can feel destitute, and a poor man in a good mood is rich beyond words"

  • Savasana (corpse pose) has been done at the end of yoga practice for many centuries to relax muscles as much as possible. Early yoga has identified that this letting go as "regeneration by relaxation" and it can not only revitalize the spirit but advance the more ambitious goal of fostering healthy life attitudes

  • Scientists found entering a state of deep relaxation caused a drop in mental activity. The breathing exercises brought about what scientists called "a temporary retardation of mental functions". The cognitive exercises they did right after relaxation exercises took subjects up to twenty-six seconds longer to complete, especially on math skills.

    • The repercussions on mental slowing is temporary but had positive long-term implications on moods

  • Medical textbooks along with the official pronouncement of the US Navy states "fast breathing lowers the body's carbon dioxide levels further decreasing oxygen intake". Therefore it is always better for your body to breathe slowly and in a more relaxed

    • This is why fast breathing causes hyperventilation and can cause people to pass out

  • Slow breathing turns out to have deep mental ramification, with increases in calm alertness and awareness

  • Scientist who study animal behavior have linked slow breathing to heightened vigilance. When an animal is ready to project itself its exhalation is slow and its heart rate tends to fall

  • Many aspects of yoga reinforce slow breathing and limit the exhalation of carbon dioxide, including the repetition of mantras and chants. University of Pavia in Italy reported on a study that the repetition of mantras cut the rate of respiration by about half, reinforcing mental calmness

  • The human body has two nervous systems that are entirely distinct. The one we are conscious about starts in the outer brain and radiates out in the nerves that let us move our skeletal muscles and go about our daily lives. The second one begins in the lower brain and regulates the internal muscles, the organs, the instincts, and other primal functions - called the autonomic nervous system.

    • The medical community before held that activities with the autonomic nervous system were automatic (other than breathing) and beyond the control of the conscious mind but after studying yogis they were able to see these individuals control automatic functions such as heart rate and blood flow. It was concluded through research that yoga is able to bring about " a deep relaxation of the autonomic nervous system"

      • The star of autonomic control was an Indian yoga named Swami Rama who was able to change the temperature of his hand by up to eleven degrees across his palm

      • These advanced yogis were also able to control the adrenal glands to push out adrenaline to speed up body functions

    • The sympathetic system is the body's accelerator and the parasympathetic is the break. Working together, the two manage the body's overall energy flow, one preparing for expenditure and the other for conservation.

      • Sun Salutations works ones muscles a lot and would thus stimulate the sympathetic system, static poses lends to parasympathetic dominance

    • In 2006, scientists measured the basal metabolic rate of regular yoga practitioners which had decreased by 13% on average in half a year of practicing. This means your body is working less on an average by 13% to do daily functions

    • This however does have an impact on physiology, which creates a propensity for weight gain and fat deposition

      • Your body requires less food and fewer calories so if you continue the eat the same as you did before you will end up adding pounds

    • Important human chemical that is a major neurotransmitters and regulator of the human nervous system is gamma-aminobutyric acid (GABA). Many reports have linked depression to low GABA levels.

      • People that practice yoga compared to those that just do regular exercise (walks, runs) showed an average 27% higher GABA levels

    • In an experiment with musicians the group that practiced yoga showed a drop is anxiety and stress during solo performances compared to the control group that didn’t do any yoga

      • Yoga helps with performance anxiety

Chapter: Risk of Injury

Sub-Chapter Summary: Injury is a reality that isn't talked much but must be considered when doing yoga. Keep your body tense when coming out of yoga poses to prevent injury and avoid high risk poses if they don’t provide you much value like the headstand, shoulderstand and plow.

  • Remember to tense up and keep muscles engaged when coming out of yoga poses to prevent injury

    • Especially out of an extended side angle pose (higher risk of injury coming out of it)

  • Be especially careful when doing moves like the headstand that put pressure on the neck

    • Don’t let ego play a role in doing poses that don’t bring that much incremental benefit into your routine

    • "You have to set aside your ego and not become obsessive over certain poses"

  • When doing a shoulder stand don’t feel as you need to be completely vertical - focus on taking the pressure of your neck by going more on your lower shoulders

  • The most common injuries in yoga ranked in order:

    • Lower back

    • Shoulder

    • Knee

    • Neck

  • Avoid over flexing your neck while doing any pose to prevent any potential nerve damage

  • 62% of people surveyed that got injured believe it was due to improper teaching

  • The Yoga Alliance was formed to help mitigate improper teaching by insuring that teacher training courses globally were being accredited and taught appropriately

Chapter: Healing

Sub-Chapter Summary: To truly get the healing benefits of yoga try and hold poses for 15 seconds to 2 minutes.

  • There are two "sense organs" woven into the body’s tendons and muscles, contraction and relaxation. As muscles are stretched these two systems sent conflicting signals to the brain.

  • Initially the sense of contraction is stronger than relaxation so your muscles stay tense initially. As the stretch continues to be held this contraction signal begins to diminish on its own accord and the relaxation impulse starts to dominate

    • This typically takes about 15 seconds to two minutes. This is how long you should hold poses. Only after this time can muscles relax enough to stretch further and provide optimal benefit

  • Poses have certain healing properties. The headstand was scientifically documents to allow a group of injured participants with a torn rotator cuffs to be able to move their arm (something they were not able to do previously) without having to use surgery (9/10 participants were able to use their arm)

Chapter: Muse

Sub-Chapter Summary: Practicing Yoga can actually increase creativity by stimulating the right side of the brain

  • Yoga has scientifically been tested to show improvements in creativity by the way it stimulates the right side of the brain

  • The right brain works best at thinking holistically and is able to see situations where the whole is greater than the sum of the parts

  • The left brain excels at logic, language, math, science and reading and writing. It revels in detail, in patter recognition, in making judgements of social rank and putting them in order of past, present and future.

  • Yoga was shown to activate the right hemisphere more than the left. The areas of heightened blood flow included the frontal lobe and prefrontal cortex. Areas that are important to setting and achieving goals

Concluding Remarks: Yoga has various health and mental benefits which have been scientifically proven, however yoga does inherently have its injury risks. Stay away from the plow and shoulder stand to limit injury risk.

Styles of Yoga

  • Anusara - Lighthearted. Puts emphasis on alignment of limbs and upbeat philosophy. Uses props to ease postures.

  • Ashtanga - Serious. Features linked poses that flow together as in Sun Salutations. Ties breath to postural flow. Physically demanding

  • Bikram - Hot and sweaty. Heats practice room to loosen joints and muscles. Features twenty-six poses and two breathing exercises. Challenging

  • Flow - Graceful. Common name for styles with interconnected poses

  • Hatha - Ancestral. The forerunner of postural yoga, from medieval India. Modern forms ten to be gentle.

  • Iyengar - Precise and popular. Focuses on alignment and holding poses. Uses blocks, straps, and blankets to improve positioning and avoid injury. Trains instructors for at least two years, versus weeks for many styles

  • Kripalu - Introspective. Puts emphasis on slowly introducing more challenging poses and holding them longer. Stresses awareness

  • Kundalini - Intense. Focuses on breathing, chanting and meditating more than postures. Seeks to awaken kundalini energy at base of spine.

  • Power - Ashtanga on steroids. Many variations.

  • Sivananda - Thorough. Promotes lifestyle of moderate poses, breathing, relaxation, vegetarian diet and cheerful attitude.

  • Viniyoga - Gentle. Puts emphasis on Sun Salutations as warm-ups for more vigorous stretching

  • Vinyasa - Fluid. Links body movements with breath in a continuous flow. A yoga ballet.

  • Yogafit - Athletic. Targets gyms and health clubs. Mixes poses with sit-ups, push-ups and other exercises


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