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4/01/2024

Opinions on Nick Longrich's article

Why did modern humans replace the Neanderthals? The key might lie in our social structures (theconversation.com)


Opinions on Nick Longrich's article / Eam Taekyoung

I agree with Nick Longrich's argument above that differences in social structure may be the main reason why Neanderthals lost their competition with Homo sapiens. However, it is difficult to sympathize with the view that there is no significant difference between Neanderthals and modern humans (Homo sapiens) in physical terms.

1. Why did gorillas and chimpanzees survive and Neanderthals become extinct?
Neanderthals appear to have been in direct competition with modern humans. In particular, in the case of Neanderthals, there was a lot of geographic and cultural overlap with modern humans, which may have led to competition for resources and even violent conflict. It is highly likely that this competition contributed to the extinction of Neanderthals to some extent. However, gorillas and chimpanzees have a different ecological niche than modern humans, and have focused on adapting to their natural environment rather than directly competing with humans.
2. What is the key reason why modern humans (Homo sapiens) won the struggle against Neanderthals?
I think it is worth noting the following regarding the differences between Neanderthals and Homo sapiens.
First, compared to modern humans, Neanderthals had characteristics such as shorter limbs, larger front teeth and roots, thicker metacarpals, and thicker necks. This is interpreted to mean that Neanderthals were physically more powerful than Homo sapiens. However, his running ability appears to have lagged behind. It appears that these physical differences affected the scope of activity and contributed to differences in the size of society.
Second, Neanderthals had a crooked and rough skeletal structure with a skull shape that was an intermediate evolutionary stage between Homo sapiens and gorillas. The shape of the Neanderthal skull appears to be between that of gorillas and Homo sapiens in the evolution of higher animals. It is less spherical than the skull of Homo sapiens. This means that the degree of transition to full erection is lower than that of Homo sapiens. The low degree of transition to full erection means that the energy consumed to support the moment caused by the head is relatively greater than that of Homo sapiens. This means that regardless of the type of activity, the basic energy consumption of Neanderthals was significantly greater than that of modern humans.

y = ax + b
b of Neanderthal > b of Homo sapiens



3. Summary
Just as it is difficult for products with low energy efficiency ratings to survive in the long term in modern society, the difference in the degree of uprightness of Neanderthals compared to modern humans caused a difference in energy consumption efficiency, and this difference caused a difference in the survivability of independent beings. Meanwhile, Neanderthals were in direct competition with humans in terms of geographic, cultural, and ecological status. In addition, physical characteristics related to running fitness caused differences in the size of society, and differences in size caused differences in social competitiveness.

3/27/2024

A hypothesis about why ancient primates lost their tails before walking on two legs

 

1. Interpretation of the function of the main foot bones of humans and chimpanzees

Among the foot bones, the bones to pay attention to are the calcaneus (heel bone) and the 1st metatarsal, and structurally, they have an arch shape that exists in the middle part of the lower foot (see Figures 1 and 2).

Figure 1

Figure 2

Meanwhile, the arch that exists on the lower middle part of the foot is mainly mentioned as a prominent feature of the modern human foot, and it is believed that if the arch collapses, pain or inflammation can be caused (see Figure 3).
Figure 3

I interpret the functions of the main foot bones of humans and chimpanzees as follows.

First, in humans, the calcaneus (heel bone) is the starting point of landing during running activities and plays a role in withstanding the repulsive force generated when a large body load is transmitted to the ground. However, in chimpanzees, the entire hind foot serves this function.

Second, the more the 1st metatarsal spreads laterally across the entire sole, the stronger its role in holding something becomes. Conversely, the smaller the spread or the thicker it is than the other four toes, the stronger its effective function for endurance running where inertial force changes are not severe.

Third, the arch, which is strongly developed in humans and exists in the lower middle of the foot when running, replaces the shock absorbing role of the spine of four-legged mammals.

Fourth, it can be interpreted that the functions of the hind feet, spine, and front feet of four-legged mammals are integrated into the human feet. When running, the landing function of the hind feet of four-legged mammals is handled by the calcaneus (heel bone) of modern humans, which exists at position 1 in Figure 4 below, and the shock absorption function of the spine is handled by the arch shape and position 2. , the function of the forefoot is now handled by the 1st metatarsal and sesamoid bone located in position 3.

Figure 4

Fifth, the direction of foot bone evolution among modern humans, including chimpanzees and several other species, was in the direction of strengthening the foot bone's function of grasping objects and running for long periods of time.

However, evolution in this direction appears to have occurred through natural selection and/or leaps (mutations) rather than the will of the species. And the results seem to have a direction in which optimal economics is further strengthened in relation to energy use.


2. In Apes, the arms perform the function of the tail in four-legged mammals

Earlier, I said that the functions of the hind feet, spine, and forelimbs of four-legged mammals can be interpreted as integrated into the human foot. So what role can the arms of apes, including humans, play when running? I am interpreting it as follows.

In four-legged mammals, the tail plays a role in controlling the inertial force of the body to prevent the body from derailing due to the inertial force when changing direction quickly and suddenly. The function of the tail is clearly demonstrated in a cheetah chasing its prey at full speed. In apes trying to stand upright, the tail would have been gradually degenerated or mutated because it was located lower on the body and had the effect of reducing the ability to properly control changes in the inertial force of the upper body. On the other hand, in apes that gave up high speed, the arms were able to fully replace the role of controlling the inertial force of the tail in four-legged mammals.

However, evolution in this direction appears to have occurred through natural selection and/or leaps (mutations) rather than the will of the species. And the results seem to have a direction in which optimal economics is further strengthened in relation to energy use.





1/02/2024

A new hypothesis for why the brain capacity of human ancestors increased rapidly about 2 million years ago (Fully bipedal walking theory)

The dramatic growth of human ancestors' brains around 2 million years ago is a key topic in the study of human evolution, and several hypotheses have been proposed to explain this phenomenon. Here are the main theories and the one that is often considered the most likely:

Diet and Nutrition(Leslie Aiello and Peter Wheeler, Richard Wrangham): The inclusion of higher-quality foods, particularly after the advent of cooking and increased meat consumption, provided more energy and nutrients that supported brain growth. The "expensive tissue hypothesis" suggests that a diet rich in energy allowed other organs to be smaller, thus freeing up energy for a larger brain.

Social Brain Hypothesis(Robin Dunbar): This theory posits that complex social interactions and the development of larger social groups drove the need for a larger brain. This includes the complexities of communication, remembering individuals, forming alliances, and understanding social dynamics.

Ecological Challenges and Environmental Changes: Adapting to changing environments and ecological challenges may have spurred brain growth. This includes problem-solving, memory, spatial orientation, and understanding and manipulating the environment.

Tool Use and Technology(Kathy Schick and Nicholas Toth) : The development and use of tools may have driven brain expansion. The cognitive demands of making and using tools, which involves planning, dexterity, and understanding cause and effect, could have selected for greater intellectual capabilities.

Language Development(Steven Pinker, Noam Chomsky): The evolution of language capacities may have contributed to brain expansion, as complex language requires significant brain processing power.

Out of these, the most widely accepted and discussed is the combination of diet and social complexities. The dietary change hypothesis, especially the role of cooking and meat consumption, is often considered crucial because it provided the necessary energy and nutrients for supporting a larger brain. At the same time, the social brain hypothesis is also highly regarded, as the cognitive demands of living in complex social structures are thought to have significantly influenced brain development.

However, it's important to note that these hypotheses are not mutually exclusive and likely interact in complex ways. The dramatic enlargement of the brain in human evolution is probably the result of multiple, interrelated factors rather than a single cause.

I feel that the above hypotheses are not clear enough to completely remove the question. I believe that fully bipedalism was the main reason for the rapid increase in brain capacity between about 2 and 1 million years ago. 


Fully bipedal walking theory/Eam Taekyoung I believe that fully bipedalism was a major factor in the rapid increase in brain capacity in our human ancestors. Full bipedal walking means walking with the center of gravity of the head very close to the fulcrum where the feet contact the ground. This means walking in a position where the moment caused by the head is almost zero. Moment = weight of the head x distance the head protrudes horizontally from the point of support This fully bipedal walking minimizes the fixed expenditure of energy consumption due to posture. The resulting surplus energy increased brain activity, and increased brain activity led to the evolution of an increase in brain size. The use of fire that began about 1.4 million years ago appears to have acted as another factor in continuing this trend. It appears that complete bipedal walking itself could have been completed through the following process.



1. Extinction of the tail: The appearance of gibbons (living in the rainforest) whose long arms replaced the function of the tail.

2. Beginning of knuckle walking: The appearance of gorillas that knuckle-walk using their finger joints (living in the rainforest)

3. Beginning of bipedal walking: Approximately 21 million years ago, the appearance of Morotopithecus, which lived in the grasslands outside the rainforest by eating leaves with its bumpy molars(Morotopithecus was able to pick leaves by standing upright rather than leaning down, as leaves are everywhere on the branches)

4. Beginning of a mainly bipedal lifestyle: Approximately 3 to 2 million years ago, the appearance of Australopithecus living in open savannas/mixed savanna and rainforest/dry but water-rich river areas/bush forests, etc.

5. Beginning of deterioration of the offensive function of the jaw and teeth: Approximately 2.5 million years ago, the emergence of Homo habilis, which used tools

6. Beginning of fully bipedal life: The emergence of fully bipedal Homo erectus (about 1.9 million years ago) and the use of fire (about 1.4 million years ago) led to a rapid increase in brain capacity.

7. Evolving into a body optimized for running: Approximately 300,000 years ago, the emergence of modern humans (Homo sapiens) with bodies optimized for running.

7/17/2023

Humans conquered the earth and gained security, but lost happiness!

 5: 25: 70, Law of Balance


Do you feel like you can't live your life with one attitude? I think one attitude is possible. It's the 5:25:70 law of balance. This law exists in the things that people pay attention to. We remember Starbucks as a dark green color, but only 5% of a Starbucks store is green.





Human weaknesses

The human brain seems to have three main weaknesses: the ability to respond to gradual and continuous environmental change, the ability to manage excessive energy, and the ability to simplify complex information. Many of the problems we face in the modern world and the obstacles that make it difficult for us to live a happy life seem to be fundamentally due to these weaknesses.

D4 Mutant Gene=Exploratory Pursuit Gene

The hormone responsible for making us feel alive and seeking novelty is dopamine. But about 40,000 years ago, a mutation in the D4 gene occurred in our bodies that made our bodies less sensitive to this dopamine hormone. This paradoxically made us more stimulating. So Homo sapiens left the continent of Africa, spread out into cold Europe, and spread around the world. We also created civilizations, developed science, and are now poised to expand into space.

The repercussions of conquering the planet, gaining security and losing happiness!

In every phenomenon, for every action, there is a corresponding reaction. What is the reaction that accompanies the action of humanity conquering the world with the help of the D4 mutant gene?

Global warming, air pollution, environmental degradation, and contaminated food probably come to mind, but there's another important reaction that we don't often recognize. It's stress.

While cavemen, on average, lived a life of strong but short-lived stress when hunting and so on, as civilization has progressed and societies have become more and more secure, modern societies have become more and more common in which weak but long-lived stress is the norm. This is evidenced by the increasingly prevalent use of words like bullying, long labor hours, misogyny, and gender conflict. The powerful but short-lived stress of confrontation with animals or threatening nature has shifted to the weak but long-lasting stress of human-to-human interaction. But while our bodies are well-equipped with evolutionary systems to deal effectively with strong but short-lived stress, we don't have evolutionary systems to deal effectively with weak but long-lived stress. So our species gained safety and lost happiness.



How can we reclaim our happiness?


The 5: 25: 70 rule of balance I like to think of 5:25:70 as a "rule of life" that allows us as a species to be happy. In design, it seems to me that dominant, secondary, and background colors can be replaced by "immersion," which is when you're at your most focused on something; "preparation," which is the studying, training, analyzing, etc. that's required to make that immersion possible; and "routine," which is sleeping, eating, and relaxing, each of which should be allocated roughly 5:25:70. In a day's life, try to have approximately 1 hour: 6 hours: 17 hours of 'immersion', 'preparation' and 'routine'. It seems to me that we need to recognize that if we have one week of 'immersion' and 'preparation' (30%), then we need to have 2-3 weeks of 'routine' (=1 week x 70%/30%). Sounds too far-fetched? Yes, I think so too... from a current perspective... And within that time of 'immersion', there needs to be as much time for festivities as possible. Smartphones are eating away at our desire for festivity. What is a festival? Festivals are a bridge between work, play, and love for the sake of happiness, which is achieved by balancing work, play, and love. The balance between work, play, and love leads to happiness. When work is positive, it leads to fulfillment, but when it is negative, it leads to dominance. In the same way, play can lead to enjoyment or addiction, and love can lead to stability and stagnation. The process of a festival: even sharing of energy (food) --> music and dance --> uplifting (excitement, disappearing boundaries, opening up) --> oneness (reconciliation, restoration of life energy) --> return to daily life. Play (enjoyment) = noticeable stress relief = frequent cleanup Festivities=stress relieving function that is not relieved by play=mindful cleaning of dirt stuck in nooks and crannies Why do we go through life seeing and accepting our current pattern of life as normal? Play (enjoyment) = noticeable stress relief = frequent cleanup Festivities=stress relieving function that is not Why do we go through life seeing and accepting our current pattern of life as normal?

7/10/2023

Cardiologist recommends 'mindfulness' and my opinion on it

[Dr. Ham's Mind PT] Cardiologist recommends 'controlling your mind'

# Modern life is hard on the heart. Unlike people in the pastoral era who were relaxed and leisurely, people in the high-speed information age live with all kinds of stress, including tension, anxiety, fear, and anger, 24 hours a day.

When looking at the top 10 causes of death in Korea, heart disease ranks second after cancer. <See chart> If you add cerebrovascular disease (4th), Alzheimer's disease (7th), and hypertension (10th), cardiovascular-related diseases account for half of the deaths.


Eam Taekyoung : Almost all diseases, except for traumatic diseases, are directly or indirectly linked to poor blood circulation. Cancer is no exception. Poor circulation is caused by poor posture and breathing.


In fact, the mind and the heart are inextricably linked. The heart is the first organ that can physically feel the state of mind.

When you feel strong emotions like joy, anger, or fear, your heart beats faster. When fear strikes, the heart is shocked with a "thud". On the other hand, during milder emotions, such as crushes and excitement, the heart is racing and pounding. It slows down when you're relaxed and slows down even more when you go to sleep.

This is all part of the autonomic nervous system, which is difficult to control. In particular, peace of mind is directly related to the health of the heart. No matter how strong your will is or how mature your character is, if your heart is weak or beating uncontrollably, it is difficult to find peace of mind. A healthy heart leads to a healthy mind.


Eam Taekyoung : The expression "the heart is an autonomic nervous system that is difficult to control with human will" seems to be half right and half wrong. This is because it is difficult to control directly and consciously, but it can be controlled indirectly and through habitual training.    


What do cardiologists think about the causal relationship between the mind and the heart?



# Dr. Michael Roizen, a professor at the State University of New York Medical Center who was named "America's Top Doctor" for nine consecutive years in the 1990s, explains in his medical bestseller, You: The Owner's Manual.


✔ High levels of negativity are bad for your heart and can add nine years to your life expectancy.

 People with depression are four times more likely to have a heart attack than those without.

 In the 30 days after September 11, 2001, heart attacks tripled in Washington, New York, Chicago, Missouri, Kansas, and Alabama.


  Dr. Park Sung-wook (67), who is considered an authority on angina treatment and coronary stenting in Korea, said.

"The hypothesis that the state of mind or stress directly affects the heart has not yet been clearly established medically, but it is true that the sympathetic nervous system of modern people is very hyperactive, which puts a strain on the heart, and there are many cases of this in real life."

There are cases of normal people suddenly having a heart attack due to extreme stress, such as the death of a spouse or loss of a job, and there are also many patients with stress cardiomyopathy (takotsubo cardiomyopathy) who show symptoms of acute myocardial infarction even though they have no cardiovascular abnormalities.


Eam Taekyoung : Why is the sympathetic nervous system of modern people so hyperactive? We are living in a modern society that is rapidly transitioning to a sedentary society with a body that has evolved for running-centered activities. More specifically, our hunched posture is causing our chest space to become compressed and slowly shrink, which in turn reduces our total daily breathing capacity. Overall, the decrease in total respiratory volume and the decrease in the time between stiffness and relaxation of the muscles on the left and right sides of the body centered on the spine are the main causes of poor blood circulation.  


In addition, there are cases where people who complain of having a fast heartbeat even though they do not have cardiovascular disease are referred to psychiatry, and vice versa.


Eam Taekyoung : Metals generally have a yield strength and a tensile strength. Yield strength refers to the external force that starts to change the length or shape when the given external force disappears, and tensile strength refers to the external force that starts to break the metal. In the modern world, we tend to live our lives in a hunched posture and under constant low-intensity stress. As a result, our physical and psychological yield and tensile strengths are getting lower and lower. Even a small amount of excessive physical and mental disturbance in our daily lives can easily cause us to reach our yield or tensile strength. 


The biggest concern is an acute myocardial infarction due to atherosclerosis, which can be fatal. It's worth noting that about half of these patients don't have any major cardiovascular problems. Suddenly, they're under a lot of stress and are at risk for atherosclerosis, myocardial infarction, and sudden death.


# The things that help the heart and blood vessels are known to be lifestyle habits that control smoking, diabetes, and obesity, and dietary habits that avoid bad cholesterol. Dr. Park also recommends "walking in the fresh air and sweaty aerobic exercise."


Eam Taekyoung : Quitting smoking and eating habits are important, but even more important is posture. Maintaining a posture that is more than a straight face in daily life naturally leads to deep breathing, which increases the total amount of breathing per day and reduces fatigue substances that occur in daily life. It also reduces the scope of capillaries, which is a sign of poor circulation.   


A normal human pulse ranges from 60 to 100 (usually 60 to 80) in one minute. The slower the pulse rate, the stronger the heart. It indicates a high volume of blood being pushed through the arteries at once. Some basketball or marathon runners have pulse rates in the 40s per minute.

With a slower pulse rate, the heart is working less. Aerobic exercise is the best way to slow your heart rate and build stronger heart muscle than any medication or food.


Eam Taekyoung : The heart is designed to beat in synchronization with the speed of your steps. When you walk or run, your steps per minute and your heart rate (cadence) are about the same. In the case of a marathon, the average steps per minute and heart rate per minute are both around 150. Both of these values get smaller and smaller as the speed of travel decreases. This means that when your body is running, your cardiovascular system is beating at roughly the same frequency as the number of repetitions of the load on your legs. 

This, in turn, means that the left and right muscles and the cardiovascular system are optimized to tense and relax in equal cycles. Therefore, the healthier an individual is, the more likely they are to have a complete cycle of tension and relaxation in their left and right lumbar muscles, which is the same cycle as the number of steps they take. This means that the more time you spend in a posture, such as sitting in a slouched position with both the left and right lumbar muscles tense, the worse your health may be. 

Therefore, modern people should try to walk as slowly as possible for the sake of their heart health. 


Dr. Park has a philosophy of 'emptying the mind' - the more empty the better. On weekends, he and his wife go mountain climbing, sweating and enjoying the scenery. He asks himself if it's not meditation when you control your breathing and walk cautiously and without any distractions on a rugged mountain trail. He visits mountains, national parks, and small islands off the southern coast of Halliday Island whenever he can.

  The second way he clears his mind is through giving. When he makes a donation or volunteers his medical skills, he feels relaxed.

"I don't particularly care about the afterlife, but I plan to live and die as I normally do, and I won't leave much to my children, but I will use what I can and donate the rest," Dr. Park said.


Eam Taekyoung : The philosophy of emptiness, mountain climbing, scenic viewing, walking, meditation, giving, and going with the flow. The word that runs through these all is breathing. Deep breathing.


Dr. Park, who joined Asan Medical Center as a professor of cardiology when it opened in 1989 and is still practicing on the front lines, served as the president of Asan Medical Center (2011-2016) and is now the president of Asan Medical Center (2021-). What is his secret?

"I do my best to do my job, but I try to forget the bad thoughts that arise while working as much as possible. Rather than trying to force them out or suppress them, I try to put them on the back burner and let them fade away as I engage in exercise or other good things."


#HamYoungJoon #Michael #Roizen #ParkSungWook  #heart #disease #mind

6/27/2023

Can a broken spine be repaired?


[Youngjun Ham's mind PT] How Fixed the Broken Spine Without Surgery(chosun.com)


# If you were hit by a car traveling at 90 kilometers per hour and suffered a fractured vertebrae, would you believe that you healed naturally through meditation without the help of modern medicine?

It actually happened, and she wrote about it, became a best-selling author, and an educator and entrepreneur sharing her natural healing methods with the public.

Joe Dispenza (1962-) was 23 years old in 1986 when he was riding his bike in a triathlon and was hit by an SUV and thrown to the pavement. Multiple spinal compression fractures. Six vertebrae were broken and twisted, and if she didn't have surgery within three days, she would be paralyzed for life. The surgery involves placing a 20- to 50-centimeter-long steel rod (Harrington rod) in her spine, and even if she heals, she will have a hard time living a normal life.

After much deliberation, he decided against the doctors' suggestion and decided to take matters into his own hands. In fact, Dr. Dispenza was already running a clinic in Southern California as a chiropractic specialist who uses spinal manipulation to heal without drugs.

A form of sports medicine, chiropractic is a manual treatment of abnormalities in the nervous, muscular, and skeletal systems, based on the premise that all disease stems from compression of the spinal nerves due to vertebral misalignment. In other words, Dispenser was an expert when it came to his back. What's more, he had been practicing martial arts and yoga for a long time.


Eam Taekyoung : Chiropractic believes that all diseases stem from pressure on the spinal nerves due to vertebral deviation. I believe that posture, stress, and food are the roots of all diseases, including cancer, except those caused by viruses. I also believe that almost all degenerative diseases, such as lung disease, cardiovascular disease, brain disease, and neurological disease, are caused by long-term accumulation of forward head protrusion and V-shape footed walking. 




He was a firm believer in the body's natural ability to recover. The ability of the body to heal itself is the philosophy of chiropractic and the theoretical foundation of holistic practitioners.

The power that created the body heals the body." He was discharged from the hospital and began his rehabilitation in a bright room at a friend's house.

At first, he ate little raw food. This was so that much of the energy used for digestion could be better used for wound healing.

I meditated and self-hypnotized for an hour three times a day, morning, noon, and night. In my mind's eye, I pictured each vertebra in my spine and envisioned a perfect spine. He also practiced reiki, a common practice in Eastern medicine. She would place the hands of visiting relatives on her wounds to channel their unconscious energy.

Finally, I applied physical stimulation to the wound to replenish the calcium in the broken bones. An inclined table was placed next to the bed, and he carefully rolled over, constantly stimulating his spine.

After six weeks, I started swimming, feeling my body recovering quickly. At first, I floated on top of the water while lying on a chaise longue, wearing thick clothes that immobilized my body. Later, he learned to float in the water and then stand, and later he was able to swim with his whole body.

By week 8, he was able to crawl on bare ground and progressed to walking, sitting, and bathing on his own. By week 12, he was able to lift dumbbells and finally walked for an hour on his own, no longer needing therapy.


# The key here is his meditation and self-hypnosis. He spent three hours a day visualizing his bones fusing and healing in his head. This is the kind of "mental rehearsal" that athletes often do. It takes a lot of mental focus and energy. Eventually, he overcame his illness and became a "meditation evangelist".


Eam Taekyoung : I think the above spinal imagery, mental rehearsal, or mental vision can be explained more scientifically as 'neurosensory perception' and 'attentional concentration effect'. 

Postural Science: Perceiving body specificity through neurosensory isokinetic tornado flight


His book, [You Are the Placebo] became a New York Times bestseller and has been translated into Korean. He travels the U.S. and around the world giving lectures, courses, and testimonials of people who have been healed of mental and physical illnesses by him. His $2,299 retreats sell out in a matter of days.

While he has many supporters, critics call him a "pseudoscientist who sells meditation as a cure-all," and the mainstream U.S. media hasn't taken him seriously.


# But when you take a closer look at his theories, they don't seem too far-fetched.

Perhaps the reason he is criticized is that he claims many of the theories already published in neuroscience, brain science, epigenetics, and quantum physics as if they were his own scientific theories, and sometimes he seems to make money by "cosplaying" as a spiritual guru.

In any case, the idea that we can create a new life by changing our minds and brains with our own consciousness, beyond our genes and environment, is hopeful in today's complex world.

In the end, his story is in line with the old saying, "If you have an intellect, you have a heart. It also reminds me of the saying that the "Iron Lady," former British Prime Minister Margaret Thatcher (1925-2013), lived by since she was a child.

"Thoughts become words, words become actions, actions become habits, habits become character, and character becomes destiny."

6/26/2023

Relationship between Step count, Arm shape, and NFSM


Natural Foot Steps per Minute (NFSM) is the number of steps per minute that you walk naturally without bending your elbow. It's a simple pendulum, like a wall clock or a Viking ride.

This number depends on the length from the center of your palm to your shoulder joint. A first-grade child with an average arm length of about 0.4 meters would have an NFSM of 95, while an adult with an arm length of about 0.55 meters would have an NFSM of about 81.



When the number of steps taken is greater than the NFSM, the elbow begins to bend as the arm moves forward, and the faster you walk, the more the elbow bends.

When you run, your elbows are typically bent at about 90 degrees or less, and the faster you run, the smaller the angle.

When walking slower than the NFSM, the elbow does not bend, but a rotational component is added to the linear motion of the hand. The slower you walk, the greater the rotational component.