Thursday, September 21, 2017

How to handle exercise related muscle cramps

We've all experienced muscle cramps at one point or another. While theories abound, there is limited consensus on why exercise-associated muscle cramps (EAMC) develop and how to get rid of them.

Etiology: The most widely held beliefs for why people develop cramps are (a) dehydration and electrolyte imbalance and (b) altered neuromuscular control. Science favors the latter explanation. In a non-cramped state, there is a balance between the activity of muscle spindles and the activity of golgi tendon organs. Muscular overload or fatigue, as well as other factors, causes an imbalance in the activity of these local receptors. The result is an overall increase in alpha motor neuron activity, which ultimately produces a cramp.

Risk factors: Some hypotheses as to why people might experience EAMC include age, body size, exercise intensity and duration, previous or current injury, gender, family history, genetics, and a history of EAMC. The strongest risk factors are a history of EAMC, male gender, and prolonged and relatively vigorous endurance exercise. Cramps may affect men more than women because men possess more fast-twitch muscle fibers, which fatigue more quickly than slow-twitch fibers. Also, women oxidize more fat and less carbohydrate than men, which may make them less prone to overload compared with men. These are merely theories, however.

Treatment: Common treatment practices include electrical cramp induction, kinesiotaping and compression garments, massage therapy, electrolyte supplementation and hydration, corrective exercise, stretching, quinine, pickle juice, and hyperventilation strategies. Stretching seemed to offer the greatest relief.
Prevention of EAMCD should attempt to offset muscular overload and fatigue. Strategies might include foam rolling or massage, scheduling adequate rest, and placing special emphasis on muscular balance in resistance training. Stretching still appears to be the best treatment for an acute bout of EAMC.

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Monday, September 4, 2017

Don't give frozen foods the cold shoulder

People tend to frown on frozen vegetables and fruits, but fresh isn't always best. In a paper published in the June 2017 issue of the Journal of Food Composition and Analysis, researchers measured the nutritional content (vitamin C, vitamin A, and folate) of three types of produce--fresh, frozen, and fresh-stored (purchased fresh and then refrigerated for 5 days)--over a 2 year span. Items examined were broccoli, green beans, blueberries, and strawberries.

In the majority of cases, vitamin content did not vary among the three categories, but when there were significant differences, frozen fruits and veggies bested fresh-stored versions more often than not. While fresh produce is typically most nutrient-dense at harvest, nutrients degrade during shipping, while foods sit on store shelves and until we retrieve the items from our refrigerators. On the flipside, the frozen counterparts are flash-frozen almost immediately after harvest, which locks in nutrients and keeps them from degrading.

The takeaway? Buying fresh fruits and veggies from local sources and eating them immediately is probably still best, but convenient and budget-friendly subzero produce is a nutritious fallback. Besides, people who work subzero fruits and vegetables into their diets have been shown to benefit from higher produce intakes overall than those who shun them, and the former also have higher intakes of essential nutrients like potassium and calcium.

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Stress, Weight Gain, and Exercise

School work, social situations, family challenges--young kids are faced with a great deal of pressure and perhaps lack the proper outlets to handle it. And as previous research has shown, stress and weight sometimes go hand in hand. A new study shows that exercise may help kids manage stress and prevent weight gain. Parents of 325 children around 7 years old provided information about the children's stress and physical activity levels. The youngsters then completed a 20-meter shuffle test to measure fitness levels and underwent body mass index (BMI), skinfold and waist circumference assessments. 
 
The researchers found that "children experiencing elevated school related stress had lower BMI, body fat, and waist circumferences if they had high fitness and physical activity levels, as compared with their less active peers." The findings indicate that policies aimed at reducing overweight and obesity should include the promotion of physical activity both inside and outside the school context. In their conclusion, researchers also highlighted the importance of strengthening children's capacities to cope successfully with school-related pressures.

Tuesday, August 8, 2017

Nutrition Crazyness

Nutrition has been making headlines for the past few decades. And those headlines can make it difficult to eat healthily. In the 1970s, eggs were vilified because they were high in cholesterol. Research had shown that high levels of LDL cholesterol in blood were linked with an increased risk of heart disease and stroke, and we knew eggs were packed with cholesterol. But it turns out that most of the cholesterol in our bodies is made by our liver and doesn’t come directly from our diets. You can’t fit that kind of nuance into a headline.

The stereotypical problem with news covering nutrition, said David Klurfeld, a nutritional scientist with the USDA, is that studies not designed to answer specific questions are portrayed as though they do.

Observational studies touting the health benefits of coffee have been in the news recently. Researchers followed coffee drinkers and non-coffee drinkers and monitored when and how they died.

Observational studies like these are useful for identifying interesting trends, but they do not demonstrate cause and effect. To test whether coffee prevents a certain disease, the researchers would need to conduct a randomized controlled trial. In this type of experiment, volunteers (preferably hundreds of them or more) are randomly assigned to one of two groups. In this case, one that drinks coffee and one that abstains.

Only when multiple observational studies, randomized controlled trials and experiments in animal models or individual cells all point to the same answer do responsible scientists begin to draw conclusions about nutrition. The results of all of these studies taken together can help inform us about how to improve our diets.

Unfortunately, news can’t wait until a consensus is reached. So here are a few strategies you can use to identify which headlines you should pay attention to. First, make sure the study was conducted in actual living humans. Then, determine whether the study was observational or based on a randomized controlled trial.

Whether the news is reporting on an observational study or a randomized controlled trial, Dawson and Ludwig recommend applying the “sniff test.” Ask yourself whether the claims make sense with what you know of your own experiences and human evolution.

There are lots of dietary trends that don’t pass the sniff test. Consider the fat phobia that erupted about the same time eggs made the bad food list. Ludwig called the low-fat craze a “nutritional disaster” because it caused many Americans to give up things we now know to be exceedingly healthy, like avocados, nuts and full-fat yogurt, while reaching for sugar-packed alternatives. Claims that cutting any given food from our diets will cure us sound too good to be true because they are.

Most importantly, “don’t change your diet based on one study,” Klurfeld advised, especially if that study has a small effect or contradicts a whole lot of other studies.

So next time you hear that chocolate will help you lose weight, cocktails protect you from heart disease, bingeing on sugary fruit juices cleanses your liver, ancient grains like wheat are toxic, or an extra two cups of joe a day will make you immortal, ask questions. How strong is the evidence? Are there multiple studies saying the same thing? And does it pass your common-sense sniff test?

What we do know about nutrition comes from repeated studies with a variety of methodologies in large populations and with mechanisms tested in animal models that show the same thing: Eating lots of fresh fruits and vegetables is good for you. Eating a low-fiber, high-calorie diet packed with sugar and fat is bad for you. But that’s not new or news, so those studies aren’t going to make headlines.

Amid the headline mania, if you want some surefire dietary advice to hold onto, Klurfeld predicts “moderation and variety are the two nutrition rules that are never going to change.”

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New Treatment Guidelines for Chronic Low Back Pain

While some people with lower-back pain may doubt whether movement is the answer, new treatment guidelines from the American College of Physicians (ACP) recommend nondrug therapies as the first line of treatment to relieve acute and chronic lower-back pain.

For people with acute back pain, the new treatment guidelines recommend heat, acupuncture, massage, or spinal manipulation. Initial recommendations for chronic back pain include exercise, tai chi, yoga, progressive relaxation, and mindfulness-based stress reduction.

The report advocates that drug therapies should not be considered until after other nonpharmacological methods have been tried. The guidelines are available in the Annals of Internal Medicine (2017; doi:10.7326/M16-2367) and are public.

Saturday, July 1, 2017

Muscle Biopsies, Movement, and Anti-Aging

New science shows that it's not just how much muscle you have that's important--it's what's inside it that matters most. Metabolically active muscle--the kind that's devoid of harmful fat and teeming with mitochondria, the metabolism-boosting powerhouses within cells--has a profound influence on everything from your weight to your energy levels to your risks of diabetes and heart disease. Even your chances of surviving a hospital stay or beating cancer are affected by the health of your muscle.

As the years go by and we spend more time sitting and less time moving, our muscle loses its zing. Mitochondria slowly decline in number and vigor, while fat starts to seep in. Health and vitality start to decline, leading to weight gain, exhaustion from everyday activities, and greater likelihood of lifestyle disease.

It turns out that the wealth of our mitochondria and the leanness of our muscle is bound to how much we move. When muscles need energy, they call on the mitochondria to turn glucose and fat into ATP, cellular energy. If we stay away from the gym too long, the body notices that it doesn't need as many mitochondria, and their numbers start to dwindle. Over time, this decreases our energy and capacity to burn fat.



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Monday, June 5, 2017

What is the best way to measure and monitor intensity during exercise?

Maximum heart rate is the maximum attainable heart rate for a person usually reached during all-out maximal exercise. Percent of maximum heart rate is often used as a marker of intensity and has even been used to prescribe exercise intensity. However, making a prescription based on heart rate alone, while precise, is not always very accurate.

The most accurate way of prescribing exercise intensity is ventilatory threshold. However, measuring ventilator threshold is difficult, time consuming, and requires a fully equipped exercise physiology laboratory. Ventilatory threshold is measured using collected exhaled air as you exercise at higher and higher intensities. By analyzing breathing rate and exhaled air, the two ventilatory thresholds, VT1 and VT2, can be measured. The ventilatory thresholds correspond to how your body is creating energy and how the heart and lungs are working. Training below VT1 (Zone 1) can be sustained for long periods of time, but usually doesn’t lead to much improvement in cardiovascular fitness. Training between VT1 and VT2 (Zone 2) cannot be sustained for very long, but leads to greater improvements in cardiovascular fitness. Training above VT2 (Zone 3) can only be sustained for very short periods of time and is most effective in maximizing work capacity. Heart rate matched to the laboratory measured ventilatory threshold is a very accurate way of prescribing cardiovascular intensity.

However, since we don’t all have access to an exercise physiology lab, heart rate prediction formulas have been used to prescribe exercise intensities by estimating maximum heart rate. The traditional maximum heart-rate estimation is 220 minus age. For example, somebody who is 25 years old would have an estimated maximum heart rate of 195 beats per minute. Recently, a more accurate formula for women has been suggested, 206 minus 88 percent of age. A 25 year old woman would then have an estimated maximum heart rate of 198 beats per minute. While these calculations are usually easy to compute and provide an easy marker from which you can determine exercise intensity, they should be questioned due to inaccuracies. The estimation may be 10 or 20 beats per minute more or less than your actual maximum heart rate. Basing exercise intensity on an inaccurate estimation of maximum heart rate can mean straying from your training prescription and training in a different heart rate zone than intended.

A better and more accurate way to monitor intensity during exercise is by using the Talk Test. Research has shown that one’s ability to talk correlates with VT1 and VT2. The point at which talking first becomes slightly difficult was at the same intensity as VT1. The point at which talking becomes impossible or very difficult was at the same intensity as VT2, according to the ACE-sponsored research study. Using the talk test, while not as specific as a number on a heart rate monitor, is a much more accurate way of prescribing exercise intensity. This talk test is best used when cardiovascular training is highly specific and competitive, for example an endurance athlete training for a triathlon.

Another way to monitor exercise intensity is by the Rating of Perceived Exertion (RPE), or Borg scale. Using the Borg scale, with values from 0 to 20, can help you monitor your cardiovascular intensity. A rating of 7 corresponds to very, very light training intensity. A rating of 12 corresponds to moderate intensity. A rating of 17 corresponds to very hard intensity. A rating of 20 corresponds to maximum all-out intensity. Notice how, as your fitness increases, your exertion level at a previously difficult intensity starts to decrease. For example, running a 10 minute/mile pace used to be a level 16 exertion level for you. Two months after exercising regularly, you notice that the same 10 minute/mile pace is only an exertion level 12. RPE is a useful way of monitoring progress and keeping intensity appropriate. It is best used when cardiovascular training is more generalized and less specific. A person most likely to benefit from using the Borg RPE scale is following a general weight loss program.

By focusing on exercise intensity as a personal measure that is different for different individuals, rather than a number to attain, you can set better exercise intensity prescriptions. As you become better trained, the intensities at which VT1 and VT2 are reached will increase. This means that performing the same intensity that used to be difficult is becoming easier and easier, meaning an increase in cardiovascular fitness!