The connection between the CNS and the ANS is extremely important to understand, not only because it explains the manner in which emotions are generated and experienced, but also because the stress response is conducted along the same pathways. For example, the famous “Fight or Flight Response,” starts in the brain as an activation of the limbic system during conditions of stress. Stressful situations activate the limbic system which in turn sends messages to the heart, skin, pupils, blood vessels, breathing muscles, and muscles in the jaws, neck, and upper back. When a stressor is sudden and strong the response is generally widespread and profound.
Imagine that you are alone at night in an empty parking garage when you notice a man lurking behind your car. Immediately, your heart begins to pound, your breathing quickens. You halt. Your body is telling you not to approach. “Can I help you?” you call out from a distance. The man stands taller and you can see that he is big with a menacing look on his face. “Can I help you?” he responds threateningly.
This situation happened to a patient of mine, a woman who is not generally a fearful person. She described how her heart felt like it was coming up through her throat. She turned and ran. Fortunately, she was not chased. She returned to her office where a co-worker called the police. After investigating the scene and finding no one, they walked her to her car. She drove home feeling sick to her stomach. She said that she felt her face flushed as though embarrassed and her heart rate did not calm down for the rest of the night. She had trouble getting to sleep that night and has subsequently developed a fear of parking garages which she experiences as a racy-queasy feeling in her stomach and chest.
Imagine that you strained your neck and upper back after being rear-ended at a stop light. Your car was damaged and, even though it was returned to you “fixed,” it continued to make a rubbing noise every time you turned the wheel fully to the left while moving–a sound that was not there before the accident. Your primary care doctor gave you some anti-inflammatory medicines and you were told the pain would go away as your muscles healed over the next 2-4 weeks. But the medicines bothered your stomach and the pain did not go away, in fact it got worse and you started to have difficulty sleeping as well since you could not seem to find a comfortable position for your neck. Returning to your doctor, you were given a prescription for muscle relaxants to help you sleep, and a you were referred to physical therapist. The medicine helped you sleep but made you feel extremely tired and groggy in the mornings so you stopped taking it. At physical therapy you were given ice and electrical stimulation therapies and taught stretches for your neck and shoulders. You thought that you were feeling a little better after the first week but on the second week you noticed an escalation of pain. Your P.T. increased your frequency of care from twice per week to three times per week. Unfortunately your busy work schedule made impossible for you to get away from the office that often, and your boss made a comment about your work product of the the previous few weeks since the accident. The P.T. explained that without more frequent treatment she would not be able to help you with the pain.
One month post-accident, you receive a call from the insurance claims adjuster who questions the need for ongoing care. He tells you that the accident was a minor fender-bender, that statistically you should not have even been injured, that even those who do get injured only require on average three sessions of P.T. to get well. He informs you that a lot of people try to run up big bills in the hope of getting a better final settlement, but that the insurance company’s policy was to pay for only a maximum of three sessions. He offers you $500 to settle your claim and informs you that you have forty eight hours to accept the offer or it will be withdrawn. You hang up the phone and your neck and shoulders are so tight that it feels the muscles might tear. You have a terrible headache.
This event, taken as a totality, gives us the experience of stress, and it takes place automatically, irrespective of logic or reason.
When a friend sneaks up behind us and yells, “Boo!,” the sudden surprise rings a loud alarm in the emotional brain, causing a massive discharge of neurons which then mediate the following event: the muscles in our shoulders and neck tense suddenly, our heart beats fast in our chest, and our breathing quickens. This generalized state of arousal is called the ‘startle response,’ and is the first stage of the famous ‘fight or flight’ response which is hardwired into our nervous systems at birth. The combination of the loud sound, the suddenness of its intrusion into our otherwise calm environment, and the unexpectedness of it, lead to our emotional brain’s automatic interpretation of the event as a perceived threat. Once we find out that no authentic threat exists, that we’ve merely been teased by a friend, the startle response, rather than blossoming into a full-on state of fight or flight, recedes, while other emotions begin to rise. We may feel our cheeks flush (vasodilation of the blood vessels in the face, consistent with the feeling of embarrassment), our stomachs, shoulders, and upper back tighten (tensing of the muscles consistent with feeling hurt or angry). These feelings come and go without our request or consent, serving the will of the emotional brain (limbic system), not the thinking brain (prefrontal cortex). Acting through the ANS, the emotional brain is half-responsible for one of the great dichotomies of human existence: how we think and how we feel do not necessarily agree and in complex societies may often run directly counter to one another.
There are five primary emotions: fear, anger, joy, sadness, and lust. There are many other emotions which are not considered to be primary emotions, and a primary emotion is not more intense or more important than any other emotion. The emotions are primary in the sense that all other emotions are either a variation of them (think of the numerous shades of a primary color) or consist of a mix of two or more primary emotions experienced simultaneously. For example, as mentioned above, anxiety and panic are lighter and darker shades, respectively, of the primary emotion fear. Similarly, frustration and rage are lighter and darker shades, respectively, of the primary emotion anger. Familial love, by contrast, is a mix of sympathy (which is a shade of sadness) and joy. And romantic love, the king of all emotions, is a cocktail of exuberance (a shade of joy), lust, longing (a shade of sadness), with just a dash of anxiety (a shade of fear) to keep things interesting. Part of what makes romantic love such a powerful experience is that involves the activation of so many (four out of the five) primary emotions all at the same time.
Some emotions are the product of physiological changes which take place in the chest cavity, some are primarily in the upper back, shoulders, neck, and jaws, some are primarily felt in the abdomen, and some emotions, like the startle response involve powerful physiological responses throughout the body. Variations of emotion are practically endless and, ultimately, are subjective. For the purposes of this blog, the point I am trying to make is that emotions are physiological changes which are attended by body sensations, and that these changes take place not as acts of reason or will, but automatically, unconsciously, from the parts of the brain collectively called the limbic system, and are carried out by the ANS which is not under conscious control. Emotions are much more about physiology than they are about psychology.
The Anatomy in a Nutshell
The human nervous system is divided into three parts: the CNS, or central nervous system, comprised of the brain and the spinal cord; the PNS, or peripheral nervous system, made up of all the nerves which leave the brain and spinal cord to supply the muscles (making them contract) and the skin (allowing us to feel); and the ANS, or autonomic nervous system, comprised of tiny spider web-like nerves that stimulate or sedate the activity of internal organs and wrap around blood vessels, enabling them to constrict and dilate. In this discussion, we will concern ourselves primarily with the ANS because it is the part of the nervous system which mediates the physiology of emotion and stress.
The ANS is not Conscious
Autonomic nerves are not under control of the conscious or thinking part of the brain (the cortex). That means you can’t will autonomic nerve activity. Instead, autonomic nerves carry out the directives of a part of the brain called the limbic system, a collection of evolutionarily primitive nuclei similar in function to the analogous parts of the brains of lower mammals like cats or dogs. The nuclei of the limbic system form the emotional part of the brain, enabling us to to have feelings, and are responsible for the phenomenon known as the ‘Fight-or-Flight’ response, which is the body’s way of reacting to stress. In stressful situations heart rate and breathing become more rapid, palms sweat, and muscles (especially in the back and neck) tense up in preparation for defending ourselves.
The stress response happens to our bodies automatically–whether we want it to or not. Constriction and dilation of blood vessels, speeding up and slowing down of heart rate, movement of food through our intestines, sweating, temperature regulation, and a host of other important physiological functions are controlled by the ANS, which carries out the orders of the emotional part of the brain, the limbic system, and none of these physiological changes are under volitional control. We can move, speak, and think through conscious intention, but we cannot change the physiology of our bodies in this way. We can control the way we behave while under stress but we cannot control how we feel in our bodies when our physiology changes during the stress response. You can act surprised (or scared, or happy, or brave, etc.) but you cannot make yourself feel or not feel the bodily sensations which accompany these emotions. It is often said that the heart wants what the heart wants, which is to say that our feelings, unlike our thoughts, are not changeable through debate or other rational processes.
The ANS Has a Brake and an Accelerator
The ANS is divided into two parts: the sympathetic division which speeds and tightens things up, and the parasympathetic division which relaxes and slows things down. In this way, the sympathetic division, usually referred to as the sympathetic nervous system or SNS is like the accelerator pedal of a car, while the parasympathetic division or PSNS acts a little like a brake.
It is commonly assumed that emotions are a function of thought, but that isn’t quite right. Let’s take fear as an example. Fear is an emotion which begins when nerve cells in the limbic system are aroused in response to some threatening stimulus. If a person has a fear of heights then riding in an elevator to the top of the Empire State Building is a stimulus that will arouse the limbic system to initiate the physiological responses we experience as feeling scared. Constriction of blood vessels in the gut (making the stomach feel sick or tight) and in our legs (making them feel weak and wobbly); increased cardiac and respiratory rates (making our hearts beat fast and our breathing rapid and shallow); activation of sweat glands (making our palms and underarms become moist), and dilation of the pupils of the eyes are all part of the fear response.
When our hearts start to pound, our palms become sweaty, our breathing becomes rapid, and our stomachs go tight or sick, that’s how we know that we are feeling scared. Sometimes when we are scared, we behave as though we are feeling excited, glad, angry, or nothing at all. How we choose to show our emotions is not always an accurate or complete revelation of our true feelings. Let us take a moment to consider the case of Mark, a patient of mine who reported that a co-worker of his was going through a particularly painful divorce. Mark felt sorry for his co-worker. But he also resented having to pick up the slack since she had stopped doing significant portions of her job. It had been several months and her lack of focus, frequent taking of sick days, and inability to complete vital tasks assigned to her was getting worse, not better. Mark felt trapped. On the one hand, he had sympathy for his colleague. On the other hand, he felt taken advantage of. He had personal problems of his own but did not bring them with him to the workplace. He feared confronting her as she seemed emotionally fragile to him and did not want to be labeled as uncaring. At the same time he resented coming in early, staying late, and using his weekends to do someone else’s work. He was trapped, emotionally speaking, in a state which we sometimes refer to as cognitive dissonance. Fear of hurting his emotoinally fragile colleague and looking bad in the eyes of coworkers was preventing his confronting her about her not doing her work; without confronter her he
Variations in the relative intensities of each of these physiological responses are what account for the varying shades of the primary emotion of fear that we all feel at certain times: anxiety, nervousness, panic, terror, etc. For example, if we start with fear, then decrease the heart and respiratory rates a little, while increasing the intensity of the stomach discomfort, we are now experiencing anxiety. If we start with anxiety and then strongly increase the cardiac and respiratory rates (tachycardia and hyperventilation) we are now experiencing panic. Prolonged panic can make us feel light-headed and may even cause us to pass out. This experience has been well described as what is known as a panic attack. Our bodies, through activation of the SNS by limbic system, create the physiological experiences we know as emotions. The variations of the fear response represents the body’s way of responding to specific types and levels of perceived threat.
Perhaps most interesting is the fact that we can experience an emotion (such as fear) without consciously registering that we are, in fact, afraid. Going back to the earlier example in the elevator, if the person with fear of heights rides to the top of the Empire State Building he may still be entirely unaware of the fact that he is afraid, even as his body is feeling strong fear-feelings in his chest, stomach, and legs. He may say to himself, “This is safe. A billion people have done this and no one has ever been injured. It is more dangerous to cross a busy street or drive a car than it is to go to the top of this building and I am not afraid of doing those other things, therefore, I am certainly not going to be afraid of this.” Though the logic of such thinking is hard to refute, emotions, quite famously, are not logical, and a person with fear of heights cannot avoid the physiology of fear: rapid breathing and heart rate, wobbly legs, sweating, dilation of the pupils. If he gets to the 110th floor and tries to walk out onto the observation deck, he may in fact experience a panic attack and faint. Knowing that we are safe does not mean that we are therefore not feeling scared.
Exercise is one of the Five Pillars of health and may be the most important of all. Strength training, flexibility training, and cardiovascular exercise (CE) are each important. Core strength is the best defense against spinal degeneration and chronic back pain. Flexibility training is necessary for breaking adhesions and fixations and for maintaining normal motion. And CE trains the heart and lungs, burns adipose, and lowers inflammation. Perhaps the most important thing to keep in mind is that, while each type of exercise promotes health in a slightly different way, each also facilitates the others. Increased strength and flexibility improve our ability to enjoy CE without pain and injury. Similarly, CE improves circulation and stamina, making us less prone to injury during flexibility and strength training. In a broader sense, CE supports the goals of healthy diet and proper supplementation. Together they form three of the five pillars of the Anti Inflammation Lifestyle, moving us in the right direction along the Continuum toward optimal health.
Exercise and Inflammation
Over the last two decades the role of inflammation in the progression toward disease has emerged as a primary focus of researchers and clinicians alike. While all body tissues seem to be at risk for the effects of inflammation, heart disease has been the primary focus of investigation. Today, inflammatory markers are routinely used as indicators of cardiovascular health. They act as indicators to show the amount of inflammation in the arteries and vascular system and are emerging as the best and most reliable test not only for determining whether or not a patient has suffered a cardiovascular episode such as heart attack or stroke, but also as an indicator of the level of health (or disease) in patients who have not yet suffered such an event. Chronic low grade inflammation is involved in all stages of the pathogenesis of atherosclerosis.(1) Circulating markers of inflammation, such as C-reactive protein (CRP), interleukin-6 (IL-6), and interleukin-8 (IL-8) have been identified as having independent roles in this development.(2) As a result, elevated levels of inflammatory markers may serve as potential indicators of the risk of cardiovascular disease.(3) Studies have also shown that there is an inverse association between levels of physical activity and inflammatory markers(4). However, not all forms of exercise exert this anti-inflammatory effect. In a landmark study, subjects were separated into two groups: one which underwent daily cardiovascular exercise (CE), and one group which underwent flexibility and strength training exercise. At the end of ten months the CE group had reduced serum IL-6, IL-8, and CRP levels, while the flexibility and strength training group did not show any any change in inflammatory markers.(5)
How CE acts to lower inflammation is not yet completely understood. The release of inflammation suppressing hormones and/or the suppression of pro-inflammatory hormones may be part of the story. But one mechanism by which CE exerts this effect seems clear: CE causes a reduction in adipose tissue. As discussed in Part I of this series, abdominal fat (adipose tissue) releases various pro-inflammatory substances, including IL-6 and IL-8.(6) In the above mentioned study, the CE group showed a reduction in adipose after 10 months, whereas the group performing flexibility and strength training did not.
For years we have known that cardiovascuar exercise causes the release of morphine-like compounds called endorphins which cause a feeling of well-being, sometimes referred to as the ‘runner’s high.’ But recent research has also demonstrated that CE raises seratonin levels. that CE also causes an increase in mitochondria inside of brain cells.
Exercise increases the size and number of mitochondria in the brain of mice (American Journal of Physiology, September 2011). The mice ran on a treadmill for an hour a day, six days a week, for eight weeks. This could explain how exercise improves memory, treats depression, and makes people feel better and helps them to think more clearly. Until now, the leading theory to explain how exercise improves memory and treats depression was that exercise causes the brain to release endorphins, morphine-like compounds that can improve mood (Journal of Applied Physiology May 1982). However, endorphins would not explain the improvement in memory and brain function associated with a regular exercise program.
Mitochondria are tiny chambers in cells that turn food into energy more efficiently than any other process in your body. Scientists have known for years that exercise enlarges and increases the number of mitochondria in muscle cells, to increase strength, speed and endurance; but this is the first research paper to offer a plausible explanation why exercise improves memory and relieves depression.
This increase in brain mitochondria could also explain how training for sports increases endurance by making the brain resistant to fatigue. It also could explain how exercise treats mental disorders, delays aging and improves certain types of nerve damage.
Cardiovascular exercise (CE) trains the heart and lungs, improving oxygen absorption and distribution to the cells of our bodies. Those of you who have taken a course in anatomy and physiology may be familiar with the principal known as Wolff’s Law. More than one hundred years ago, the German Anatomist Julius Wolff, noticed that when animals were sedentary, their bones got weaker and more brittle (what we now call osteopenia and (when severe) osteoporosis). Conversely, he was able to show that animals with osteopenia/osteoporosis could improve and strengthen their bones by becoming more active. By loading weight onto the bones, the body physiologically adapted, meeting the new demand for activity by actually remodeling the bone tissue, making it harder and denser. Wolff’s law, at its essence, can be summed up by the phrase: ‘Use it or lose it.’ And Wolff’s law, it turns out, applies to more than just the bones. Muscle, lung, heart, even brain function improves with use and diminishes with inactivity. Regular CE, when done correctly, improves the function of every body tissue either directly or indirectly.
Keep in mind that the changes Wolff observed did not take place overnight. Back to the concept of the Continuum, change (for better or worse) is a gradual process and so is the product not of heroic focused effort, but of our habits of living. The AIL does not involve dieting, it involves a healthy style of eating; it does not involve reaching a certain body weight goal, but rather of getting to and then maintaining healthy body fat levels through good habits. Similarly, CE, with its profound anti-inflammation and pro-circulation effects, is not something to be done until one ‘becomes healthy.’ Failure to exercise the heart and lung regularly will cause you to lose function of these vital organs. Regular CE over long periods of time enables you to gradually improved their function. Making CE a part of your lifestyle enables you to maintain cardiac and pulmonary health for life. What’s more, improving heart and lung function results in improved oxygen absorption and distribution to the cells of our bodies and CE exerts a profound general anti-inflammation effect on the body.
Flexibility training is the second form of exercise. Stretching is the most common form of flexibility training and it is vital for improving and maintaining mobility. Doctors commonly speak of (and routinely measure) something called ‘Range of Motion’ (ROM), which compares the movement of a joint or body area against a set of pre-determined ‘normal’ values. But ROM, measured in degrees of movement, while useful for certain medical purposes, is an artificial construct. ROM measurement has poor inter-examiner reliability (every doctor reads the ROM differently), does not adjust for age, gender, or body type, and captures only a very limited amount of data about mobility. In addition, the stereotyped movements associated with ROM do not reproduce normal, natural body movement and, inversely, the vast majority of normal body movements which involve the complex coordination of many muscles are not part of standard ROM testing. Range of motion is not the same thing as mobility.
Our bodies are designed in layers. Around the chest, abdomen, and pelvis are deep, intermediate, and superficial layers of muscle tissue separated from each other by wrappings called fascia. These fascia-wrapped layers are sometimes called ‘fascial planes.’ Optimal function of the musculoskeletal system includes the easy gliding of these fascial planes against
each other. Twisting and reaching, bending, pulling, and pushing, all involve the coordinated contraction of many groups of muscles, movers and stabilizers, and depend on the ability of deep, intermediate, and superficial muscles to glide easily against each other.
The healthy gliding of fascial planes is maintained by complex movements which are part of our physical nature. The more we move, the more lubricants our joints produce and the more freely our fascial planes glide. But for many of us, the routines of our daily lives take place in very limited ranges of movement. We drive to work, sit at computers, talk on telephones, relax on sofas, eat at tables. How often do we jump as high as we can, run at top speed, or climb a tree? When was the last time you used all of your strength to do anything? If you are like most people, you are not coming anywhere near the limits of what you are physically capable when it comes to either movement or strength/effort. Which is why the occasional moving of furniture, digging out a bush, or participation in a yoga class can leave us sore or worse–injured.
Certainly, we derive benefits from our civilized existence, but we also pay a price. Inactivity means loss of strength, reduction in the production of lubricants (which compounds the effect of loss of collagen and other important components of connective-tissues as we age), and the development of fixations and adhesions–the drying out and sticking together of our connective tissues including the fascial planes which are essential for movement and optimal musculoskeletal function.
Over the last 5 years, a new form of movement, known as ‘Dynamic Spinal Stretching (DSS)’ or Stick Stretching,‘ first developed by Dr. Arthur Feygenholtz, has been gaining popularity for Diffuse, low-grade cellular inflammation causes our fluids to thicken, and the lubricants we produce to aid in motion to become sticky like glue. Over time, this glue locks connective tissues together. When this happens at a joint, it is referred to as a ‘fixation.’ When it happens between muscles or their fascial coverings, it is called an ‘adhesion.’ As fixations and adhesions develop, complex movements like turning to look behind you when backing out of a parking space become more difficult. We chalk it up to the aging process, but in truth, there is much we can do to prevent and reverse the progressive formation of joint fixations and myofascial adhesions. Stretching, sports such as basketball and volleyball which require us to reach, jump, and twist our bodies, and the practice of yoga with its compound movements and poses are just some of the ways people have found to improve mobility. Ask anyone who plays such a sport or has a regular yoga practice how they feel about it and they will tell you that there is a certain feeling of well-being which comes from these activities which they cannot get any other way. They may not be able to articulate exactly what that feeling is, but there is a sense of bodily freedom which comes from breaking adhesions and fixations which is truly rejuvenating. Breaking adhesions helps to reverse the feeling of stiffness which is one of the primary symptoms of the aging process.
its unique ability to break up fixations and adhesions by allowing deep stretching to take place across the broad fascial planes of the body. Dr. Berkoff has used this technique to develop a series of stretches and movements which he has incorporated into his Kore Klass routine which can be done at home. Since lower back pain affects 80% of Americans at some point in their life, and more than 20% of all people over the age of 30 have recurrent or chronic lower back pain and discomfort, Kore Klass was developed as an essential part of health maintenance. Dr. Berkoff tries to interest all of his patients in three things: the Anti-inflammation Lifestyle (AIL), a Core training or back routine, and stick stretching, the Kore Klass.
Physical exercise can take three different forms:
1. anaerobic or strength training exercise
2. flexibility training
3. aerobic or cardiovascular exercise
Strength training, is important for maintaining overall well-being and for supporting the body’s weight-bearing joints, especially the spine. Weight lifting is the primary example of this form of exercise, but there are other ways to build strength as well. Strength training does not rely primarily upon the ability of the body to utilize oxygen and hence is sometimes referred to as anaerobic exercise. It involves an increase in heart rate for short intervals as a person performs each set of an exercise. The heart rate gradually comes down during the rest period between each set, then elevates again during performance of the next set, or the next exercise. In so doing, the heart and lungs undergo a small amount of training, mostly in the form of recovery training (this will be discussed a bit later when I talk about cardiovascular exercise). A small amount of calories are burned as well (typically about the same as during walking) which is an additional benefit.
While most experts maintain the importance of strength training in overall health, the medical understanding of its role is somewhat controversial, since studies do not bear out a strong disease-preventive benefit from this form of exercise. In the past, it was commonly held to be true that increasing muscle mass–the main physiological effect of strength training–results in faster, more efficient fat burning. However scientific investigation has not supported this link between weight lifting or other forms of strength training and body fat reduction.
In the last two decades, the focus of musculoskeletal clinicians has been shifting away from ‘bulk-building’ to something called ‘core strengthening.’ The concept of core strengthening is that there are muscles in and around the mid and lower trunk (abdomen, lower back, and buttocks) which are essential for stabilization and support of the spine. These muscles, taken as a group, are referred to as the ‘core.’ Disuse of these muscles cause instability of and excessive load bearing by the lower spine, resulting in various forms of disease and dysfunction. Chronic lower back pain affects approximately one fifth of adult Americans, and failure to maintain good core muscular strength is undoubtedly one of the principle causes. To the extent that strength training is essential to good health, it is becoming more and more clear that core strengthening is the centerpiece of this form of exercise. I will say more about core strengthening and about a new device, the Kore Power Trainer, at the end of this paper, under the section ‘Putting it All Together.
For now, what is important to understand is that if you have experienced lower back problems, are planning to become pregnant, or if you are over 30 years of age, you have a simple choice to make: begin to take care of your core or suffer degeneration of your back. By now you will not be surprised to learn that back health is measured along a continuum, and long before you have a break down, poor habits can lead to weakening, fibrosis, and degeneration of joint, bone, and muscle tissue, or ‘pre-disease.’ I have developed a basic back routine which can be expanded upon or edited back to fit the needs and abilities of every patient. Regardless of the reason you came to see me as a patient, learning the healthy back routine is an important a part of your well-being and you are encouraged to request this training at any time. Learning the back routine usually requires two office visits.
The ‘core’ is a term widely used to refer to the group of muscles in the lower back, abdomen, and pelvis which, when used properly, support and relieve pressure from the weight-bearing elements of the spine. A strong, well-coordinated core means better overall body strength and less chance of injury, especially during activities which require lifting, pushing, pulling, and twisting. For decades, chiropractic doctors, physical therapists, and other musculoskeletal practitioners have promoted the idea of strong abdominal muscles as the key to a healthy lower back. But until recently, a strong core meant lying on your back and doing sit-ups which only work a very limited part of the Core. Working the rectus abdominus (the ‘six pack’ muscle) has its benefits, but doing so in isolation does not result in a strong core as it does little to defray compressive loads carried by the spine and offers little support for movements such as pushing, pulling, lifting, and twisting. Ask Dr. Berkoff about the Kore Power Trainer, a device which can be used on any standard bed to train ALL of the muscles comprising the Core, including the rectus, the obliques, and the muscles of the lower back and buttocks.