Surprising new ways to build healthy knees

Improving balance, losing weight, and strengthening muscles help prevent injury and reduce pain.

One of the most common reasons people visit their doctor is because of knee pain or injury. Arthritis, ligament and meniscal tears, fractures, dislocations, and sprains can limit your mobility and take away your independence. “Difficulty walking, climbing stairs, squatting, and getting up and down from chairs are common complaints from people with knee pain,” says Michael Orpin, a doctor of physical therapy at Harvard-affiliated Massachusetts General Hospital.

Keeping the knees healthy helps prevent injuries and reduce pain. Work with a physical therapist to develop a strengthening plan, which will likely include the following.

Exercise above the knee

There are many muscles in the hip and thigh that play an important role in knee health. Some of the major muscle groups include the quadriceps in the front of the thigh, which extends your knee and holds your body weight on a bent knee; the hamstring muscles, which bend the knee; and the gluteal muscles located in the hips. “Weakness of the hip muscles can create excessive inward twisting of the leg during normal weight-bearing activities, such as going down stairs, and can lead to higher levels of stress across the knee joint,” says Orpin. He recommends exercises that work many muscle groups at once, such as moving from a sitting to a standing position repeatedly. That’s called a sit-to-stand. “If it’s painful to do this from a chair, try it from a higher surface like the edge of a bed,” says Orpin. He suggests doing three sets of 10 sit-to-stands. 

Exercise below the knee

The gastrocnemius muscle, the largest muscle in your calf, crosses over the back of the knee and plays an important role in assisting with knee control. This muscle, inaddition to the soleus muscle, helps propel the body during walking, stair climbing, and running. Weakness in this muscle group could contribute to more stress through the knee joint. Orpin recommends heel raises to strengthen the calf muscles. Hold on to a counter for balance. Slowly rise up on tiptoes, then lower heels to the floor. That’s one repetition. “Try three sets of 15 repetitions,” he says.

A focus on balance

Part of maintaining balance requires your knees to work with other joints that enable you to stand−the hips and ankles. But the coordination takes practice.  A physical therapist will help you improve your balance by training your muscles to work together with simple exercises. For example, you may stand with one foot right in front of the other, as if you were standing on a tightrope, and eventually stand on one leg for up to 30 seconds.

Weight loss

The focus of each pound you carry is magnified by the time it reaches your knees. If you’re walking across a flat surface, the force on your knees is equal to one-and-a-helf times your body weight; going up a hill, the force is equal to two to three times your body weight.  Shedding extra weight reduces the force on your knees, which can help prevent arthritis and injury, and also reduce existing knee pain. “When patients lose weight, they describe feeling lighter on their feet, having more energy, with less knee pain and intensity of symptoms,” says Michael Orpin.

To aid weight loss Orpin suggests aerobic activity that won’t overload the knee, such as riding a stationary bike. “It’’s easy on the knee, and it promotes a good range of motion of the joint,” he says. Light to moderate walking is also beneficial if  it’s not painful. “If a pool is accessible, this is a great place to exercise. The water reduces weight on your joints and can make it easier to move. Try walking in the water forward, backward, and sideways to challenge different muscles,” says Orpin.

Harvard Health Newsletter

WAKE UP, DRINK WATER

Unless you're hooked to an IV drip all night, you're more dehydrated in the morning than at any other time of day. Yet most people chug coffee and wait until afternoon to uncork their water bottles, which can result in a sluggish midday ride. (Coffee's high water content delivers some hydration, but it's not as potent as straight-up H₂O). "Water helps carry nutrients and oxygen to working muscles," says Jennifer McDaniel, CSSD, spokesperson for the Academy of Nutrition and Dietetics.

Do I Really Need New Running Shoes?

When Should You Buy New Running Shoes?

How long does a pair of running shoes last?

How often should I get a new pair?

These questions are two of the most often asked questions at running shoe stores. It usually comes up after the running shoe salesman has drug out three or four pairs of shoes and the customer likes more than one model. The customer then gathers final facts to come to a decision.

What are we talking about here? It's not whether the rubber on the outsole has peeled off, or stitching in the upper wears out. Rather, these questions are in regards to how long the cushioning and/or support lasts. The heart of shoe cushioning lies in the midsole—that foamy layer of, well, foam. It looks like marshmallow fluff. The most common bed of cushioning in running shoes is a rubberized form of EVA, the acronym standing for ethylene vinyl acetate, a thermoplastic polymer has applications ranging from surfboards to biomedical engineering. When you slip on a pair of untouched running shoes with a soft, bouncy midsole of compressed EVA, it can feel as if the floor beneath your feet has taken on the quality of a trampoline.

But as you and I know, that feeling—best described by Ray Bradbury in Dandelion Wine, with the character named Douglas magically bounding into the summer in a pair of "Cream-Sponge Para Litefoot Shoes"—doesn't last forever. At some point, you notice that they feel flat.

So the question, How Long Will They Last? usually refers to the life of the midsole. . Here are answers I've heard over the years of hanging out in running shoe stores and having worked in running shoe stores.

"Every 500 miles." (back in the 1990s, this is the one I used)

"Every six months."

"Every three months if you can afford it."

"Every 400 miles.

"Every 400 to 600 miles."

"Every 1000 miles."

"Depends on if you run on the roads or the trail."

"You can get more life out of them if you buy two pairs and rotate them in your usage."

No confusion there right? Not surprising since there are multiple variables involved. Not to mention the sticker shocks. Run 50 miles a week in $150 shoes and every two and a half months your gear-and-apparel budget is getting some serious drainage.

"Here are some fun facts," says Jay Dicharry, author of Runner's Anatomy: Unlocking Your Athletic Potential for Health, Speed, and Injury Prevention. Dicharry is a physical therapist and biomechanics expert, and is a key advisor to Ironman champion Linsey Corbin. Reports Dicharry, "One well designed research study shows that shoes lose about 40 percent of their cushioning by the time they've reached 200 miles. So the old adage to 'throw them out at 500 miles' isn't really an an all-or-nothing thing. Shoes break down with use, starting from the first step. And research shows that the body adapts slightly to adjust to these changes."

It's the last part that spurs Dicharry to let us know what can be done to take more control of the situation. Including the likes of Corbin, Dicharry essentially conducts research experiments with his clients and their biomechanics, studying the patterns of movement in fine detail to look not just for injury-inducing flaws that can be corrected, but for real-time, intricate adaptations that can help him better see opportunities for increased power flow.

"In general, people make small adjustments in their motion to minimize the mechanical work they are doing. It's kind of a self-preservation strategy to maintain efficiency."

Dicharry adds that sometimes these minute changes in range of motion are harmless. They allow a triathlete or runner to keep on trucking just fine in lifeless, broken down shoes.

"I had a previous runner that had excellent biomechanics," Dicharry says. "He wasn't really dependent on the shoe for anything, and routinely got 1200 to 1400 miles out of a single pair of shoes."

Right: Dicharry is talking about those runners like Dean Karnazes, who apparently have such perfectly-spun mechanics that they can run across the country and back with nothing more damaging than blisters.

As for the rest of us, one of the ways we know a shoe has lost it's cushioning is that nagging injuries start lighting up in the way of a pinball machine.

"There runners are more sensitive to the small changes in gait—either due to their structural needs as a runner or their biomechanics—and begin to feel symptoms brought on like clockwork every time they hit 'X'-number of miles."

What can we do? Dicharry encourages the latter-type of athlete (most of us, as suggested by injury data) be more like Karnazes and other seamless runners.

"One strategy to prolong the life of your shoes is to improve you," he says. "Make yourself less dependent on the shoes by relying more on your inherent foot stability." This is done, Dicharry says, by strengthening your feet. "Shoes do matter, and make a difference, but 100 percent co-dependent relationships are never a good thing."

Sweat It's Good For You!

Sweat: how to keep your cool

Americans spend huge sums of antiperspirants and tend to see sweating as sloppy or unclean. Many would gladly take a pill that prevented perspirations altogether. But such a pill would be deadly, since sweating’s primary− and crucial−function is to cool the body. When sweat evaporates, heat is removed. Sweating is particularly essential during exercise and, of course, in hot weather.

    You perspire when your body’s temperature rises and also in response to emotional stimuli such as anxiety, fear, or sexual arousal. Millions of sweat glands pump the fluid, which comes primarily from the blood, up through ducts to the surface of the skin.

    There are two types of sweat glands. Heat-regulating function appears to be limited to eccrine sweat glands, located all over the body, including the feet and palms. In contrast, apocrine sweat glands respond to emotional and nervous stimuli. Connected to hair follicles, they are located mostly in the armpits, groin, and around the navel. In most mammals, apocrine perspiration helps attract a mate through scent, but it’s unclear what role this plays in humans today.

What is sweat?

It’s mostly water, with small amounts of sodium, chloride, potassium, and other minerals (collectively called electrolytes) that play an important role in regulating blood pressure and the body’s water balance. Sweat from apocrine glands is different, however, and gives sweating a bad name. It contains proteins and fatty acids, and it mixes with oil and dirt, making it thicker and slightly yellowish. Body odor comes from compounds released by bacteria feeding on organic particles in apocrine sweat.

How much do people sweat?

Sweat rates vary greatly. Sedentary people may sweat anywhere from a negligible amount to two quarts a day. Under extreme conditions, heat and physical exertion can increase the output to as much as two quarts an hour. Factors such as age, sex, genetics, and conditioning affect the amount a person sweats.

Why does exercise increase sweating?

Your working muscles burn lots of calories and thus produce heat, which raises body temperature. The body reacts by increasing blood flow to your skin, which helps remove heat by a process called convection, and also causes you to sweat more, which cools you off by its evaporation.

Do you sweat more hen it’s humid?

Yes, but the sweat doesn’t cool you off, since it doesn’t evaporate as much and simply drips off. That’s why a hot, humid climate feels more uncomfortable than a hotter but drier climate. Air movement does promote evaporation of sweat, so a fan may help−for instance, while you’re exercising on a stationary bike or lifting weights.

How does sweating make you thirsty?

Sweating reduces blood volume by removing water and thus boosts the concentration of sodium in the blood, which stimulates the brain to trigger thirst. But when you exercise or work hard, the thirst mechanism doesn’t keep up with your need for fluid. By the time you’re thirsty, you’ve already lost a lot of fluid. A fluid deficit of even a pint or two can impair physical performance. Always drink before, during, and after prolonged exercise, especially in the heat.

Is prolonged sweating dangerous?

It can be. You can lose excessive amounts of both water and sodium during severe and prolonged sweating−for example, when working outside in hot weather. When you don’t replace water lost through perspiration, blood volume drops, you sweat less, and body temperature rises. This can hurt performance and lead to heat cramps, heat exhaustion, or heat stroke (a life-threatening condition characterized by body temperature of 104°F or higher and often severe headache, rapid pulse, and possibly loss of consciousness). Sports drinks or salty snacks can provide some sodium during endurance exercise. In the long term your normal diet will replace the minerals lost in sweat.

Is sweating a lot a sign of fitness or lack of fitness?

It depends. As you become physically fit, your core temperature will rise more slowly, your heart will be able to beat more slowly at a given workload, and you’ll sweat more efficiently. For instance, you’ll start to sweat at a lower core body temperature and sweat more (the amount can nearly double in ten days of training in the heat)−assuming you’re fully hydrated when you start. Thus you stay cooler and can exercise more in the heat. Your sweat is more diluted, containing less sodium and other minerals. Just as exercise increases efficiency and size of muscles, it boosts the efficiency of the heat-regulation system and even the size of sweat glands. On the other hand, sedentary people usually sweat a lot because they deal poorly with the heat−their core temperature rises faster, the heart beats faster, and they sweat more at a given workload than well-conditioned people, and thus they become more fatigued.

Do you get used to the heat?

Yes, especially when you exercise regularly in hot weather. Changes in your cardiovascular and nervous systems (such as a lower heart rate and increased blood flow to the skin) help you acclimatize to the heat. Your sweat glands become bigger. Most of the adaptation occurs during the first five days, but full acclimatization takes about two weeks. The fitter you are and the more you exercise in the heat, the faster you’ll be able to adapt. After a few days back at normal temperatures, you’ll lose most of these adaptive changes.

Why do older people have such a problem when there’s heat wave?

Because their cardiovascular system is usually less fit. Thus they tend to pump less blood to the skin (but with a greater strain on the heart), sweat less, and thus are less able to dissipate internal heat. Coping with the heat can seriously tax the heart of anyone who is not healthy and fit. In addition, older people can more easily become dehydrated because they tend not to feel as thirsty as their younger counterparts, so they should make a special effort to drink plenty of fluids. Well-trained, healthy older athletes, however, can usually cope well with the heat.■

Is exercise really medicine?

The many benefits of physical activity are continually backed by mounting research.

Exercise is medicine. The expression started as the name of a health initiative and is now a catch-phrase used by doctors, fitness experts, and others who want to motivate you to move. But is physical activity really as effective as prescription medications? “Yes, I do think of it as medicine, and even better, it’s medicine that’s free and has very few side effects,” says Dr. I-Min Lee, a Harvard Medical School professor who studies the role of physical activity in preventing disease promotion health and well-being, and enhancing longevity.

Mounting evidence

The health benefits of exercise have been noted since Biblical times. Modern science has confirmed ancient wisdom: physical activity can greatly reduce your risk of heart disease, stroke, type 2 diabetes, breast and colon cancer, depression, and falls. Physical activity improves sleep, endurance and even sex. And scientists continue to learn more about physical activity’s medicinal qualities every day.

   For example, an October 2013 BMJ study found that exercise is often as effective as drugs at preventing death from the most common killer diseases, such as cardiovascular disease and diabetes. An April 2014 study in the British Journal of Sports Medicine found that regular aerobic exercise appears to boost the size of the hippocampus, the brain area involved in verbal memory and learning. A May 2014 study in Circulation showed that even small increases in activity, such as a faster walking pace or more time spent gardening or doing other leisure activities, can improve heart function. The list from the past year alone goes on: post-meal walking helps regulate blood sugar levels; strengthening and flexibility exercises reduce pain from hip and knee arthritis; exercise programs can improve the cognitive functioning of people with dementia.

   Is physical activity an effective treatment on its own? In some cases, yes. It can be all that’s necessary to reduce the symptoms of depression and anxiety. When combined with weight loss, it can help keep someone in the early stages of diabetes from needing medication. Does physical activity make medications more effective? “We don’t know that yet,” says Dr. Lee. “But physical activity should be regarded as a first-line therapy, together with pharmaceutical treatments.”

How exercise protects health

“The human body was designed so that all physiological functions are optimal when we move,” explains Dr. Lee.” And increasingly we are realizing it doesn’t take much activity.” Harvard scientists have discovered that when you exercise, your muscles release natural substances that help relax blood vessel walls, lower blood pressure, reduce “bad” LDL, cholesterol, increase “good” HDL, cholesterol, move glucose out of the bloodstream and into the cells where it is needed, lower insulin levels, and reduce inflammation. All of these functions together help protect us against heart disease, stroke, type 2 diabetes, and some cancers.

What you should do

Dr. Lee says it’s time to add physical activity to the list of daily health requirements, such as wearing a seat belt or brushing your teeth. “There really is nothing I can think of where physical activity will not help in terms of disease or function,” she says.

   Take this prescription: Aim for half an hour of moderate physical activity most days of the week, or 150 minutes a week. If that seems daunting, start with a few minutes a day, and increase the amount you exercise by five or ten minutes every week until you reach your goal.’  

   If you don’t want to walk, consider other moderate-intensity exercises, such as swimming, stair climbing, tennis or dancing. Don’t forget that household activities can count as well, such as floor mopping, yard work, or anything that gets your heart pumping so much that you break out in a light sweat.

   Don’t have the discipline to do it on your own? Join a class, or work out with a friend who’ll hold you accountable. Or track your progress, which encourages you to reach a goal. Use a pedometer or a digital fitness monitor to count steps.

   And if you aren’t able to perform moderate-intensity exercise, remember; even light activity can make a difference in your health. ♥

Univwesaity of California Wellness Letter Volumne 30