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

Fitness at an Elite Level

Training for a win with motocross sensation Ken Roczen

Supercross star aiming for the top with dedication, diet, steady gym time

March 27, 2014 by Leah Crane

Rookie sensation Ken Roczen has blazed his way into the supercross main event. Training hard off the track has helped him stay there.

Nineteen-year-old supercross racer Ken Roczen is having a standout year. After winning the AMA Supercross Lites West Series in 2013, Roczen made the jump up to the 450 class for the 2014 season and some wondered how he would stack up against a field filled with past champions like Ryan Villopoto, Ryan Dungey, James Stewart, and Chad Reed, who all have dominated in the 450 category for the past decade. When he burst out of the start gate at the season opener at California’s Anaheim 1 in January and won the final, he left the doubters in the dust.

It was a big jump for the Red Bull Teka KTM Factory Racing Team rider and German native, but thanks to a combination of focus and steady training Roczen hasn’t let off the throttle. While he will admit freely that exercising in a gym is not his favorite activity, this year he’s stepping it up a notch and working with renowned trainer Aldon Baker. As former professional cyclist, Baker has made a name for himself in the motocross world with a past and present client list that reads like a who’s who of the sport. Former trainees have included Ricky Carmichael and James Stewart, so Baker’s well versed in the physical demands of being on the podium. Currently Baker trains Roczen alongside three-time supercross champion Ryan Villapoto (who currently leads the 450-class point standings in front of Roczen) and lites leader Adam Cianciarulo.

GrindTV recently caught up with both Roczen and his trainer to gain some insight into the workouts and diet of the professional motocross rider. According to Baker, his approach to Roczen’s training is not unlike the one he’s used for other motocross riders. “I think it’s a combination of areas that need to be addressed, and you need to take into consideration the athlete’s age, genetics, and previous injures,” he explains. “Then I build a plan that improves on weakness from the past. The main factors needed are cardio and usable strength with agility and flexibility. And then maintaining a strict plan with the physical training and the on-track riding.”

Riding in circles

Roczen is quick to point out that having the increased strength required to tackle the new bike size has been a huge motivator. “You need to be stronger when you hop on the 450,” says Roczen in an interview with GrindTV.com. “You want to ride the bike and not let the bike ride you. You also have to have the endurance. In 450s we’re racing 20 laps instead of the 15.”

Baker is quick to point out that training seriously is just what Roczen needed to make the jump to the heavier and more powerful bike. “The transition to 450 is tough and requires a lot more strength and agility,” says Baker. “Once I had done tests on Kenny, I [knew I] needed to get his leg strength more balanced and work his cardio more. And then [we could] increase the workloads that would be needed to get through a 450 season.”  

Agility workouts require fast-twitch muscle fibers, which helps Ken Roczen improve his reaction time on the bike. This is great for keeping an athlete sharp and fit without being bored. For Roczen, putting in the proper training means he’s in the gym or out exercising nearly every day, like it or not. Because the schedule is largely set for supercross athletes, with competition taking place each Saturday night in a new location, all athletes fly into the event on Fridays and back out on Sundays. This schedule allows Roczen to be at home in Florida for four solid days. He’s on the dirt bike for practice on Mondays, Wednesdays, and Thursdays, and is working out like a madman in between.

“I’m pretty sure everyone [in motocross] does the same thing,” Roczen says. “It’s a circle between running, rowing, cycling, and exercise—and obviously riding. And then I let my trainer do the setup: when, how much, and how long. Honestly, I don’t like any of the [gym] exercises. Tell me one person that likes exercises. There are so many exercises that we do; it’s not like we go do one thing. We’re often doing 10 things. I’d say I actually enjoy running—running and cycling.” Box jumping is a great all-around exercise that helps increase Ken Roczen’s leg strength and add agility with cardio.

Food for thought
When Roczen isn’t out on the bike or in the gym, he’s refueling for his next effort. Though Roczen doesn’t have any strict dietary restrictions, Baker has given him plenty to think about. “Nutrition is really important for maintaining a healthy body and power-to-weight ratio on the bike,” explains Baker. “It’s also huge with recovery. I do address his eating habits and plan his meal plans and ratios accordingly. The basics of good nutrition are no fried foods, no sugar and salt, bake or steam vegetables only, and cut out refined carbohydrates like breads and white pastas. Also, no red meat, dairy products, and cheeses—instead, substitute with almond milk and soy products.”

Not surprisingly, race-day meals are pretty simple for Roczen. “It’s fish or chicken and some rice and vegetables; that’s basically always the deal,” he laughs. “On race day, we start pretty late. My first practice, I think, is usually at 1 [p.m.] or something, and then we have three practices and the last session ends at about 4:30. After that I’m usually eating something and then I’ll actually lay down and take a 20- to 30-minute power nap. After I’ve slept, I usually go hop on the spin bike and get myself warm and get my heart rate up again for the races.

“I’ll snack all day, but obviously nothing bad,” he continues. “I like the Nature Valley granola bars or a banana between races, and then [I] try to relax and calm myself down. Then, 20 minutes before I go back out, I’m back on the spin bike. It’s not like I’m coming in every time and eating, though. You for sure want to keep something in your stomach, but it’s not that I’m eating the whole time. I’ll have a bar before lunch, between riding sessions, and then I’ll come in from the heat race and have a banana and that’s it.” 

With only five events left this year, Roczen is currently ranked fourth overall in the point standings. This puts him 10 points back from third place, a 26-point deficit from second place, and 49 points behind first. But because a single event win can give a rider 25 points, the season is anything but wrapped. At this point, it’s all about racing smart, securing podium finishes, and hopefully coming out on top. And that is where Roczen is hoping his training will kick in.

Improve your balance by strengthening your core

Your abdominal, back, and hip muscles can help you avoid falls.

Are you walking a bit more carefully lately, or feeling unsteady on your feet?  You may be struggling with a balance problem. That puts you at risk for falls, one of the top causes of injury among older adults. But strengthening your core muscles-in your abdomen, back, and hips – can help. “Core strength is intimately related to balance, because you need good stability at your core to have safe and effective movement at the hip, knee, and ankle,” says Kailin Collins, a physical therapist at Harvard-affiliated Massachusetts General Hospital.

The Core muscles

You can think of the core as your foundation. It’s made up of several muscle groups: The rectus abdominis (“abs”) at the front of your abdomen; the internal and external obliques, in the front and side of the abdomen; the tranversus muscles that run horizontally across your lower abdomen; the erector spinae, the large muscles on either side of your spinal cord; the muscles surrounding your scapulae (shoulder blades); the gluteus muscles in your hips and the buttocks; and the iliopsoas and quadrates lumborum muscles in your pelvis.

            These muscles provide stability to your trunk. They link your upper and lower body and enable you to move in any direction or stand in one spot without losing your balance. “If your core isn’t strong or stable, it will be impossible for the arms and the legs to move well,” says Collins. A weak core can undermine the motions that are part of your everyday life, such as walking bending, turning, dressing, and bathing, let alone the larger movements of sports activities.

Strengthening

Core strengthening is a popular trend in health clubs because of the many benefits that result. In addition to stabilizing your balance, a strong core improves your posture; reduces stress and pain in your lower back; and improves athletic performance, such as swinging a golf club. Strengthening usually includes strenuous exercises such as planks, sit-ups, push-ups, and crunches. Equipment such as balance boards, stability balls, and Bosu balls may also be used.

            For older adults, that type of activity can be dangerous, especially if your balance is unstable. But core strengthening can be as simple as small, repetitive movements, such as front and side standing leg lifts to strengthen your absl, shoulder blade squeezes to strengthen your scapulae, and a pelvic tilt to strengthen your abs. In that exercise, you lie on the floor with your knees bent and then gently roll your pelvis into the air.

Where to start

If you’re feeling unstable, you’ll need to see a doctor before beginning an exercise routine. Instability may be related to problems with your inner ear organs, vision, muscles, or joints. They all send signals to the brain, which processes the information and sends signals back to your muscles to make the movements necessary to maintain balance. Imbalance puts you at risk for falls. “As we get older, falls can become much more traumatic, and are often the reason for hip fractures, rib fractures, and head injuries. These can all lead to significant health problems among older adults,” says Collins.

            If your doctor recommends physical therapy to strengthen your core, you’ll go through an evaluation to determine and prescribe the right exercise routine. Once you’ve been assessed, your PT will likely guide you through a series of gently stretches and strengthening exercises.

            Don’t wait for balance problems before you start working on your core. You can prevent balance problems, as well as back pain, by maintaining a strong core at all times. Just make sure that initially you work with a physical therapist or personal trainer, who can tailor a core-strengthening program to your specific needs. We list some typical exercises that can help strengthen your core above. You can also pick up a copy of the Harvard Special Health Report Core Exercises. Go to www.health.harvard.edu/core for more information.

Alternatives

Strengthening exercises are a great way to tighten your core and improve your balance, but so are other forms of exercise that give your core a real workout. Yoga involves postures, concentration, and controlled breathing that can strengthen our core and increase your flexibility. Tai chi is another effective core strengthener. It’s a form of Chinese martial arts that includes deep breathing and slow movements and postures. Both of these exercises are helpful to improving your balance and are safe for people who may have health issues that prevent more aggressive or energetic activities.

Harvard Health Letter – February 2014