Pesky Piriformis

With the advent of MRI, we seemed to have blamed all shooting pain like sciatica to discs. Slipped, bulging, herniated, torn, smashed, compressed, protruding, extruding, you name it.

And you can't blame us. On MRI, you have a pretty view of the disc. "Look, see it protruding out like that."

The problem with this is that nerves can be compressed or stretched against other tissues. Some of this tissues are hard like bone, but a lot of times they can be soft like muscle or fascia.

One such muscle that can cause a lot of trouble in sciatic-type pain is the piriformis muscle. It lies deep in the middle buttock area and can do great job irritating the largest nerve in the body that runs near it, the sciatic nerve. We title this simply Piriformis Syndrome.

People have variations in where the sciatic nerve lies in relation to the piriformis. Most of the time the nerve is under, sometimes under, and sometimes through.

Various ways have been developed to stretch the piriformis such as the figure-four stretch, to loosen the piriformis fascia with tools such as Graston or Therapy Edge, and to control movement with strapping such as with Kinesio Tape. Exercise therapy designed to stabilize other pelvic muscles and take pressure off the piriformis can be of great help as well.

Please, visit our website at http://www.oklahomawellness.com/ and further blogs at http://www.oklahomawellness.com/blog/blog.html

The contents of the this site, such as text, graphics, images, and other material contained on the site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the site! If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by Back to Health Wellness and Chiropractic, Michael K. Van Antwerp, DC, Back to Health Wellness and Chiropractic employees, others appearing on the Site at the invitation of Back to Health Wellness and Chiropractic, or other visitors to the site is solely at your own risk.

Achilles heel

Popular antibiotics known as fluoroquinolones, which include Levaquin (levofloxacin) and Cipro (ciprofloxacin), have been associated with a potential increased risk of ruptured tendons. The main tendons affected are shoulder, hand, and Achilles.

Levaquin is prescribed for lung, sinus, skin, and urinary tract infection (UTI) treatment when such infections are caused by certain bacteria. Cipro is prescribed for urinary tract infections such as acute uncomplicated cystitis, pyelonephritis, and chronic bacterial prostatitis when certain bacteria cause such infections.

The tendon problems may spontaneously occur within a few days of taking the antibiotic or months after the course of therapy is finished.

Further research needs to be perform, but it seems as if fluoroquinolones cause cell death in the tendons thus weaking them. More and more case studies1,2 and lawsuits are occurring. Levaquin and Cipro's weakness literally has been their "Achilleios pterna," that is Achilles' heel.

Sincerely,

Michael K. Van Antwerp, DC, CPed, CCSP

Back to Health Wellness Center
2433 N Aspen Ave,Broken Arrow, OK 74012

918-259-3000

Reference:
1. Mathis AS. Levofloxacin-associated achilles tendon rupture. An Pharmacotherapy: 2003; 37:7:1014-1017.

2. Haddow LJ. Spontaneous achilles tendon rupture in patients treated with levofloxacin. J Antimicrobial Chemotherapy: 2003; 51:3:747-748.


Please, visit our website at http://www.oklahomawellness.com/ and further blogs at http://www.oklahomawellness.com/blog/blog.html



The contents of the this site, such as text, graphics, images, and other material contained on the site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the site! If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by Back to Health Wellness and Chiropractic, Michael K. Van Antwerp, DC, Back to Health Wellness and Chiropractic employees, others appearing on the Site at the invitation of Back to Health Wellness and Chiropractic, or other visitors to the site is solely at your own risk.

Tip the Scale

Just some quick tips from Men's Health to lose your belly:

"1. Drink more water: Wake up to 16 ounces of cold water in the mornings, and you'll do three important things: jumpstart your metabolism, hydrate for better burning throughout the day, and fill your stomach. Reach for water throughout the day instead of food—many times our body confuses hunger for thirst.

2. Eat breakfast every day, and pack your lunch: It takes less time than you think—store last night's dinner in a plastic container, and you're all set for the next day.

3. Lift and run: The most effective strategy is a one-two approach of weightlifting and high-intensity interval training. According to a recent University of Southern Maine study, 30 minutes of pumping iron burns as many calories as running at a 6-minute-per-mile pace for the same duration and builds more muscle.

4. Sleep: Lack of shut-eye may disrupt the hormones that control your ability to burn fat and can promote unhealthy nighttime eating. Aim for 7 hours each night. Can't sleep? Review your goals, both weight loss and otherwise."

Lose Big Time!

Ways to lose fat:

1. Diet.
2. Exercise.

That’s it.

There is no fancy schmancy pill, elixir, fad-of-the-month, machine, or other person that can do it for you.

Diet is not a “diet” that you go on, but rather a lifestyle of what type of fuel you put in your mouth.

Exercise is not performing certain moves in a gym, but a lifestyle of activity.

In my experience, diet makes up 70% of losing fat, and exercise makes up 30%. You cannot lose inches on your waistline if you work out but eat poorly.

Questions to ask yourself:
1. How often do I eat out?
2. How much sodium is in the food I eat?
3. How much refined sugar is in the food I eat?
4. How processed is my “food”? That is, how far away from nature is it?
5. How many “white” foods do I consume? Flour, bread, sugar, potatoes, rice?
6. How much corn containing products do I consume? Chips, high fructose corn syrup, fillers, on the cob, kernal?
7. How many fresh, organic fruits and vegetables do I eat with each meal?
8. How much processed meat do I eat? Sausage, lunch meat, pepperoni, bologna?
9. How many foods do I eat out of a box or bag at home?
10. How often do I find myself sitting in a drive thru or running into a convenience store for “food”?
11. How many foods do I eat that are fried and/or breaded?12. How much fresh, purified water do I drink?
13. How often do I sit during the day? Car, desk, computer, meetings, couch, TV, movies?
14. How often am I moving? Walking, running, swimming, cycling, soccer, weight lifting, hiking?

Diet. What to put in your mouth? Lean protein. Fruits and vegetables. Meat should be about the size of your palm and as close to natural as possible. Fruits and vegetables should be as close to their native form, ripe, and organic as possible. Do not buy the bulk of your fruits and vegetables from your regular supermarket. They lack flavor and nutrients. Buy from Whole Foods, Akins, Martha’s, or your local farmers’ market. You really don’t need to purchase anything else from these stores unless you want to buy meat. Shop the produce section and leave. Meat can be purchased from your local supermarket; they usually have “natural” varieties available. Perry’s, Harvard Meats, Oklahoma Coop, farmer’s market, and your local rancher are excellent places to purchase meat. Oklahoma has some of the best free-range beef in the country, yet it is usually sent to the east and west coast. Eggs should be from free-range chickens and possible have extra omega-3 fatty acids in them. Your local farmer’s market has excellent eggs. The difference between a mass-produced egg and a natural egg is notable in just cracking it open. If you plan on eating soy as your protein, try tempeh instead of tofu. There seems to be some controversy eating soy, and it seems the fermentation process in tempeh improves the nutritional quality.

Watch your sodium. This is not just for high blood pressure but water retention. The look of “fattened” skin under the jaws and in the face is noticeable when sodium intake goes up. Restaurants have lobbied Congress for year to not have to label their nutritional content. Watch out. Almost every restaurant out there has a huge salt intake. Some meals are the equivalent of eating two or three ramen noodle packs in one seating. 2,000 and 3,000 mg of sodium are not uncommon. What to do? Prepare more meals at home.

Water. We don’t get enough. It’s frankly one our greatest missing nutrients. You might have heard that we need to have eight glasses of water a day. This is a good place to start. However, the best way is to take your body weight number in pounds and chop it in half. This will be the number in ounces you should drink per day. For example, a 180 pound individual should drink 90 ounces of water a day. Water should be purified and fresh. If you are sweating a lot by working intensely, you need more water combined with some electrolytes. It has been shown recently that tea and other drinks help with fluid intake, but some of them can be diuretic. So stop whining about it and drink more water. Squeeze a lemon or lime in the water if you need to add flavor. A good way to stay consistent with your water intake is to pour the amount you need for the day in a large container at the beginning of the day and drink all of it by the end of the day. A cold 16 ounces of water drank first thing when you wake up has been shown to help you fire off your metabolism and lose fat. So drink up. Cheers!

Most of our food quality is never going to be sufficient. A highly absorbable organic as possible multi-vitamin/multi-mineral, antioxidant, and omega-3 supplement is essential to maintain a high level of health. Digestion of nutrients and building of essential tissues requires cofactors that are not always consistently present in our diet.

How do you plan meals? Pick a protein – lean meat, eggs, or tempeh – then add a fruit or vegetable. That’s it.
Is it really that easy? Yes and no. Yes, in that the concept is easy; no, in that it is difficult to stay disciplined.

Here are some examples. For breakfast, eat two hardboiled eggs that you have previously prepared on Sunday; add a chilled organic pink grapefruit. For lunch, eat a rotisserie chicken quarter of dark meat with green beans and broccoli grape salad at Charlie’s Chicken. For dinner, eat a quick stir fry of cubed chicken breast, ginger, garlic, broccoli, and low sodium soy sauce. Add a side salad of organic spinach leaves with a Mediterranean nut and fruit mix from Walgreen’s, a small amount of a unique cheese from Whole Foods, and a sprinkling of balsamic vinegar and olive oil.

How about some more? For breakfast, a lower calorie vanilla and orange Greek yogurt cup from Reasor’s plus an organic apple. For lunch, organic salad bar at Jason’s Deli without the bread and pasta items. For dinner, free-range rotisserie chicken from Whole Foods plus the spinach, nut, cheese, balsamic vinegar, and olive oil salad. For dessert, a stamp-sized piece of lower sugar dark chocolate with some unique flavor like cayenne or almonds and orange.

What about quick snacks when I’m raging hungry? Organic apple slices with Smart Balance Omega peanut butter. A can of low sodium tuna, rinsed, and sprinkled with balsamic vinegar and eaten straight out of the can. Low sugar Greek yogurt. Whey protein shake. Muscle Milk from QT, Walgreens, or Sams. Celery stalks with Smart Balancce Omega peanut butter. A handful of Mediterranean nut mix from Walgreens, not the dried fruit one this time.

I recommend Muscle Chow by Gregg Avedon as an excellent source of easy-to-make recipes. It is written to guys trying to look fit in the gym but is an excellent source for woman and kids alike. His shopping guides and diet cycle are excellent. The creatine and glutamine supplements he recommends are not necessary unless you’re trying to maximize your strength in a gym.

Sometimes, additional help is needed early on to control your urges. A personal trainer, nutritionist, dietician, or physician can help. Many support programs such as Jenny Craig or Weight Watchers give individuals discipline in the beginning. I have found, interestingly enough, that auricular acupuncture can help a good portion of people sedate their cravings in the early stages of life change.
Exercise. How much do I do, what do I do? You need to set aside a minimum of an hour a day for activity. Period. Some of the larger people that I have seen lose their size did so by eventually walking an hour a day. Activity includes walking, riding a bike, swimming, and weight lifting. Intensity does matter. However, in the beginning start out at 10 minutes a day for one week then add on five minutes for each additional week until 60 minutes is reached.

Intervals ignite a fat-burning furnace compared to slow, plodding “cardio” exercise. Intervals include periods of high intensity followed by lower intensity. For example, warm up for five minutes then hit near your max intensity for 30 seconds followed by one minute of slow intensity. Repeat the high/low cycle for 15 minutes. You can do this on a treadmill, outside on a trail, on a bicycle, and in a pool. This total time of 20 minutes will burn way more fat for the day than 45 minutes of steady moving. Note: if you are on a machine the 20 minutes of intervals will show less calories burned than the 45 minutes of steady exercise. Don’t worry, the interval workout makes your body burn fat for the rest of the day. Intervals work because they raise and lower your heart rate. Check with your physician before starting interval training.

Strength training is key to burning fat. Muscles require a lot of energy to work. When you use them, they will continue to burn up excess calories the rest of the day. Big muscles burn up more energy than small muscles. The more muscles you use, the more you burn.

Body weight squats and assisted pullups are two great ways to start activating big muscle groups like quadriceps, glutes, and lats. Combination of lower and upper body exercises maximize your time.

I have found that setting up time with a personal trainer, in the beginning, is a great way to get started and know how to properly perform exercises. There are some great facilities out there such as Fitness Together that provide one-on-one personal training and nutritional advice. As you become more experienced working out, you may want some variety and change in intensity. A CrossFit facility is a fun change of pace and competition.

As you may have noticed, “losing weight” has been de-emphasized in this article and losing fat and decreasing your waistline have been emphasized. Muscle weighs more per volume than fat because it is more dense. So if you start gaining muscle and losing fat, your weight may stay the same. They easiest way to monitor your progress is to pay attention to your pants size. Did you have trouble fitting into a pair of pants and now you can? Are your pants waists becoming looser? What about your jaw line? Is it less “swollen” looking? These are good signs you are along your way.

As a final note, our environment, food quality, and sedentary lifestyle have really taken their toll on our current health. Most Americans are malnourished to some degree. Malnourishment does not always take on the image of skin and bones kids in Africa with flys landing on their eyelids. It also takes on the image of a rotund American kid with high cholesterol, high blood pressure drinking a Coca-Cola for breakfast riding the bus to school and sitting hunched over eating trans-fat potato chips playing video games after school.

It is estimated that a lot of the damage that we do to our DNA is not that noticeable in our lifetime. It is, however, noticeable in several generations out. Cancer, obesity, IQ, athletic ability, and stature are some of the issues that might not just affect us from our choices, but also our future offspring.

Remember, life is a journey. Enjoy it!

Sincerely,

Michael K. Van Antwerp, DC, CPed, CCSP

Back to Health Wellness Center
2433 N Aspen Ave,Broken Arrow, OK 74012

918-259-3000


Please, visit our website at http://www.oklahomawellness.com/ and further blogs at http://www.oklahomawellness.com/blog/blog.html



The contents of the this site, such as text, graphics, images, and other material contained on the site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the site! If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by Back to Health Wellness and Chiropractic, Michael K. Van Antwerp, DC, Back to Health Wellness and Chiropractic employees, others appearing on the Site at the invitation of Back to Health Wellness and Chiropractic, or other visitors to the site is solely at your own risk.

Cracking Your Knuckles

You may have cracked your knuckles as a kid and had your mom yell, "Stop! That'll give you arthritis." Is this true or an old wives' tale?

Although cracking or popping knuckles is common, the research on it is not.

Let's start with two thoughts. What causes the popping sound, and what is arthritis anyway?

The cracking or popping sound is caused by release of gas, mainly carbon dioxide, out of solution in the synovial fluid of the joint.1,2,3 This is similar to the sound of a champagne cork releasing. The popping produces only a small increase in pressure in the joint, which has been estimated to be only 7% of the pressure needed to damage the cartilage of the joint.4 The gas takes out least 30 minutes to build back up. This is why you cannot immediately pop your knuckles again. However, other sounds may be re-occurring. For example, a snapping sound is usually a tendon or ligament sliding over a bone, and a crunching sound is usually damaged cartilage.

Arthritis is one of those words that is casually thrown around by both doctors and patients alike. Oftentimes, I'll have a patient tell me they have arthritis or a physician told them they have arthritis, and I'll ask what blood tests or x-rays have they had performed. Usually they'll reply, "none." Unfortunately, that does patients a disservice because several types of arthritis exist. The name arthritis means simply “joint inflammation”. The two main types of arthritis are rheumatoid arthritis (RA) and osteoarthritis (OA). Rheumatoid arthritis has been theorized to be an autoimmune disorder where the body attacks its own joints and causes joint inflammation including redness, swelling, and deformity. Often this has to be controlled by some type of medication and/or supplement. Osteoarthritis is wear and tear upon a joint which may result in joint space narrowing and bone spurs. Osteoarthritis is also caused degenerative joint disease or degenerative disc disease if found in the spine. A more proper name might be “osteoarthrosis” as it is seems to not have the inflammation involved with it as once thought. Psoriatic and gout are other examples of other types of arthritis one might hear.

Drs. Robert L. Swezey and Stuart E. Swezey in 1975 conducted a study of 28 nursing home residents who could recall whether or not they had cracked their knuckles earlier in life.5 After studying x-rays of the participants’ hands, the researchers concluded that there was no link between habitual knuckle cracking and arthritis.

In 1990, another study published in the Annals of Rheumatic Disease looked at a group of 300 habitual knuckle crackers.6 The researchers found that the participants who cracked their knuckles regularly were no more likely than those who did not to have arthritis.

Dr. Donald L. Unger released an article in 2004 where he reported to have spent fifty years cracking the knuckles of only his left hand twice daily.7 After analyzing the difference between his left and right hand, he found no noticeable differences and no arthritis had developed.

According to Sanjiv Naidu, Pennsylvania State University professor of orthopaedics, "Plain old knuckle-cracking should not cause any damage.8 It does not strain the ligaments or the tissues, or overextend them enough to cause arthritis," Naidu says. "It also should not cause joint weakness, on a long-term basis. Anatomically, physiologically, and mechanically, there's no reason it should cause harm."

Elaborates Naidu, "You literally have to disrupt the joint capsule through excessive force – like a ligament injury in a knee, or 'skier's thumb,' for example – to cause chronic, long-term damage.” The forces generated by knuckle-cracking are relatively small in comparison, Naidu said.

In my opinion, knuckle cracking is not necessarily a bad thing; however, taking the joint in the wrong direction so that it is misaligned can cause a host of problems. This is similar to spinal or extremity issues. “Popping” the joint is not going to hurt it if it is taken into a properly aligned position. However, if it ends up in the wrong position, acute pain might ensue or chronic wear and tear might occur over time. This is why having your body professionaly aligned is important.

Dr. V.



Reference:
1. Brodeur R. The audible release associated with joint manipulation. J Manipulative Physiol Ther. 1995;18:155-164

2. Brodeur R. What makes the sound when we crack our knuckles? Sci Am. October 26, 2001.

3. Protapapas MG, Cymet TC. Joint cracking and popping: understanding noises that accompany articular release. J Am Osteopath Assoc. 2002;102:306.

4. Watson P, Hamilton A, Mollan R. Habitual joint cracking and radiological damage. Brit Med J. 1989; 299(6715):1566.

5. Swezey RL, Swezey SE. The consequences of habitual knuckle cracking. West J Med. 1975;122:377-379.

6. Castellanos J, Axelrod D. Effect of habitual knuckle cracking on hand function. Ann Rheum Dis. 1990;49:308-309.

7. Unger D. Does knuckle cracking lead to arthritis of the fingers? Arth & Rheum. 2004; 41:5:949-950.

8. Tibbett S. Probing Question: Does cracking knuckles cause permanent damage? Physorg.com. April 13, 2006.



Please, visit our website at http://www.oklahomawellness.com/ and further blogs at http://www.oklahomawellness.com/blog/blog.html



The contents of the this site, such as text, graphics, images, and other material contained on the site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the site! If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by Back to Health Wellness and Chiropractic, Michael K. Van Antwerp, DC, Back to Health Wellness and Chiropractic employees, others appearing on the Site at the invitation of Back to Health Wellness and Chiropractic, or other visitors to the site is solely at your own risk.

Mega Omega!

If you've been in the office for any period of time, you've probably heard me mention omega-3 fatty acids from fish oil. There's a reason why.

They have a huge host of benefits that we are just beginning to understand. If a wonder capsule exists then this is it. From reduction in inflammation in joints AND blood vessels to immune function to brain power, these oils lend a hand.

So big deal. Eat more fish...or flax seed...or both. The problem is we live in landlocked Oklahoma with little access to fresh coldwater ocean fish. The fish obtain the omega-3s from the algae they eat. Lake fish and the amount of frozen ocean fish we eat doesn't cut it. Also, mercury and other contamination in our oceans is unprecedented. You max out your mercury content for the week with one filet of salmon or three cans of albacore tuna. Flax seed oil has omega-3s but not in the longer chain form such as DHA that your brain uses or the EPA that your immune system uses. It's been estimated that flax seed oil conversion in your body to these larger chain oils is very low. Therapeutic dosage on DHA and EPA is often given at 1,200 to 6,000 mg. Try eating that much fish without any mercury or PCB contamination. So what to do? Well, my solution is to suck it up and take my daily mercury-tested, micro-distilled fish oil capsule.

Omega-3 Research Studies have shown that Omega-3's can have a very positive effect on the following conditions:
* Reduce the incidence of Cardiovascular disease (heart disease, stroke)
* Reduce triglyceride levels
* Reduce inflammation and symptoms associated with Crohn's Disease
* Reduce inflammation and symptoms associated with rheumatoid arthritis
* Lessen symptoms of kidney diseases
* Lessen the symptoms of Reynaud's disease
* Lessen the symptoms of chronic obstructive pulmonary disease
* Reduce the risk of early delivery in pregnancy
* Reduce the symptoms of childhood asthma
* Possibly reduce the risk of getting Alzheimer's
* Reduce the risk of prostate cancer
* Support normal brain function
* Supports vision development in infants
* Inhibit carcinogenesis and the formation of cancer cells
* Reduce PMS symptoms and breast pain
* Maintain healthy skin
* Boost your immune function

Here is a list of research headlines from just the last couple of months, all of which can be accessed at PubMed.gov:
* Erythrocyte fatty acids and risk of proliferative and nonproliferative fibrocystic disease in women in Shanghai, China.
* Omega-3 Fatty Acid Supplementation Effects on Weight and Appetite in Patients with Alzheimer's Disease: The Omega-3 Alzheimer's Disease Study.
* Omega-3 fatty acid rich diet prevents diabetic renal disease.
* Omega-3 Fatty acids, prematurity, and autism.
* Omega-3 Fatty acids and the cardiometabolic syndrome.
* Dietary intakes of omega-6 and omega-3 polyunsaturated fatty acids and the risk of breast cancer.
* Fatty acid facts, Part I. Essential fatty acids as treatment for depression, or food for mood?
* Effects of ethyl-eicosapentaenoic acid omega-3 fatty acid supplementation on hot flashes and quality of life among middle-aged women: a double-blind, placebo-controlled, randomized clinical trial.
* Fish Oil Reduces Heart Rate and Oxygen Consumption During Exercise.
* Dietary n-6 and n-3 polyunsaturated fatty acids: From biochemistry to clinical implications in cardiovascular prevention.
* Neuroprotectin D1-mediated anti-inflammatory and survival signaling in stroke, retinal degenerations and Alzheimer's disease.
* Fish Oil, But Not Flaxseed Oil, Decreases Inflammation and Prevents Pressure Overload-Induced Cardiac Dysfunction.

I'm also excited that a 950 mg, mercury-tested, micro-distilled, enteric-coated, burp-free omega-3 fish oil capsule is available in regular size. No more choking down several capsules. You can get your daily dosage in one capsule or two.

P.S. If you have an aversion to taking in fish, krill or algae-based capsules are available out there.

Here's to improving our health one day at a time!
Dr. V.

Please, visit our website at http://www.oklahomawellness.com/ and further blogs at http://www.oklahomawellness.com/blog/blog.html



The contents of the this site, such as text, graphics, images, and other material contained on the site ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the site! If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by Back to Health Wellness and Chiropractic, Michael K. Van Antwerp, DC, Back to Health Wellness and Chiropractic employees, others appearing on the Site at the invitation of Back to Health Wellness and Chiropractic, or other visitors to the site is solely at your own risk.