How Muscles Age

Written by Science Knowledge on 1:23 AM

For the average person, age 25 is the high watermark for muscle mass. After that, muscles begin to waste away, shrinking at least 10 percent before age 50, after which the reduction quietly picks up speed. In the years after 50, adults lose an average of one-half to one pound of muscle each year—but often don’t notice the loss because fat slides in smoothly to replace it. The biological term for this phenomenon is sarcopenia. If ignored, it can leave older people unable to carry out daily activities and make them defenseless against injury. An otherwise minor accident—like a fall in the bath—becomes more likely, more damaging, and more difficult to recover from.

Many of the factors that cause sarcopenia are biological. As the body ages, it becomes more efficient in reclaiming unused muscle, and slower to recover after a bout of exercise.
The body’s levels of testosterone and human growth hormone plummet. Muscle growth slows, and some muscle fibers may die off completely. However, an equally important factor is the changing lifestyle of midlife and old age. Without continuous activity, muscles shrink, much as they do for astronauts after mere weeks of a weightless space flight.

Fortunately, there’s no need to go gently into that good night. Studies consistently show that older adults can use strength training to maintain their muscles and stimulate new growth in more or less the same way that young people can. In fact, two strength-training sessions a week is enough to keep your muscles in tune and your body in good health for years to come. (However, as you age, your body becomes less forgiving of injuries and strain. So if you embark on a new workout after 60, it’s a good idea to get your doctor’s clearance, join a workout group, and get the advice of a personal trainer.)

Source of Information : Oreilly - Your Body Missing Manual

How to Lift Weights

Written by Science Knowledge on 2:21 AM

For many people, the very idea of lifting weights is intimidating. If you’re afraid to step up to a dumbbell because you think someone will expect you to oil up your skin and grunt like bull moose, you may be one of those people.

But don’t give up just yet. The health benefits of strength training are simply too important to miss. And with a bit of up-front guidance, you’ll find that weight lifting is surprisingly straightforward. In time, it can become just as comfortable as any other workout.

First, you need a solid set of running shoes, a basic set of weights (or membership in a fitness club that has them), and a bit of self-confidence. Next, you need to understand the sort of exercises you’ll do—mostly compound exercises that work muscles throughout your body. Finally, you should study the following sections, which explain the basic principles of successful strength training. Best of all, there’s no grunting required.



Aim for the point of exhaustion
Proper strength training works only if you challenge your muscles—in other words, when you lift a weight that’s not easy to lift. Beginners sometimes make the mistake of opting for lighter weights and longer workouts. This sort of workout may boost muscle endurance, but it won’t cause the microscopic tears that spur muscle growth. Of course, choosing a weight that’s too heavy is even worse, because it can cause injury. So how do you choose the right weight? The answer lies in understanding the 8/14 rule.

Every strength-training exercise involves repeating the same action several times in a row. This is called a set. Ideally, you repeat the exercise 8 to 14 times. The right weight is one that’s light enough for you to lift comfortably and stay in control, but heavy enough that you’re completely tapped out by the last repetition. This lets you work your muscles to the point of exhaustion.



Use good form
The secret to getting a good workout with weights is being fanatical about good form. It doesn’t matter whether you’re a championship weight lifter with the body mass of a middle-aged rhinoceros or a computer genius who hasn’t left his home office in years, the rule is the same. Lift weights sloppily and you’re more likely to cause an injury. But concentrate on carefully directed motion, and your muscles will get the maximum benefit in the minimum amount of time.

The key is control. If you find that you’re beginning to lose control over the weights you’re lifting—dropping them instead of lowering them slowly— you’re lifting too much. You should be able to raise and lower your weights at the same speed for each repetition, including the last one.

This rule isn’t just a safeguard against injury. It’s also a practical guideline that helps you get the most from your workouts. When you lower a weight, your muscle performs an eccentric contraction, which means it produces force as it lengthens. (When you lift a weight, your muscle performs a concentric contraction, exerting force as it shortens, or contracts.) Modernday exercise science suggests that eccentric contractions cause more of the microscopic muscle tearing that stimulates muscle growth.

Here are a few more tips to keep in mind when you approach an exercise:

• Relax. Concentrate on slow, efficient movement. Never swing a weight or use momentum to lift it. Lowering a weight should take more time than lifting it.

• Breathe. Exhale when you lift or push the weight, and inhale as you’re bringing it back to your starting position. Don’t hold your breath during an exercise.

• Stand up straight. Pay attention to your posture, keep your balance, and hold in your abdominal muscles.

• Pain is not OK. Not even if you like it. If you find that raising or lowering a weight past a certain point causes pain, don’t push it that far (or choose a different exercise). You should perform each exercise through the greatest range of motion you can achieve without pain.

• Listen to your body. At first, you’ll lift less weight than you might expect. Conversely, as you become stronger, you’ll need to increase the weight to maintain the same level of difficulty. Otherwise, your muscles will have a picnic.

• If you’re not sure, get help. The best option is to have an experienced professional show you how to do an exercise—for example, a personal trainer at a fitness club. If you can’t do that, search for an instructional video from a reputable fitness website that shows how to do an exercise.



Always warm up
Don’t go in cold. Warming up is essential before any type of exercise to prepare your muscles and prevent you from hurting yourself. A good weightlifting warm-up starts with 5 to 10 minutes of light aerobic exercise (for example, running in place, jumping up and down, and trying not to look ridiculous). It’s also a good idea to do a warm-up set before you start each individual exercise. For your warm-up, perform the same exercise but with a much lighter weight (or no weight at all).

Source of Information : Oreilly - Your Body Missing Manual

The Stretching Controversy

Written by Science Knowledge on 2:15 AM

If you remember high-school gym class, you probably remember three things about it: a) changing clothes in front of adolescent peers is no fun; b) proper stretching is essential before any physical activity; and c) the meek may inherit the earth, but not before a few dodgeballs ricochet off their foreheads.

It now seems that the weight of modern science contradicts the second rule—in other words, stretching before exercise doesn’t do much for your joints or muscles. In fact, static stretching (where you hold a stretched position for 20 or 30 seconds) temporarily weakens the muscle, and may even make injuries more likely when you stretch at the beginning of a workout. That’s because resting muscle is stiff. It’s just not ready to meet the demands of vigorous exercise or deep stretches. In fact, static stretching may simply increase your stretch tolerance, which is a fancy way of saying that your brain will allow you to extend stretched muscles a little bit more, even though they aren’t yet warmed up and really ready for it.

That doesn’t mean that you should leap straight from the couch onto the treadmill. Before any sort of exercise, you should perform a short 5- or 10-minute warm-up. This stimulates blood flow to your muscles and literally warms up your body. It also gently loosens muscles and tendons, increasing the range of motion in your joints. Your warm-up should match the exercise you’re doing. If you’re getting ready to run down the street, start by jogging in place. If you’re lifting weights, start with a little light jogging (just enough to break a sweat) and then perform a set of your chosen exercises with a much lighter weight. Once you finish, you can begin the real muscle-straining workout. And after your workout? Recent studies suggest that just as pre-exercise stretching doesn’t prevent injury, post-workout stretching does little for muscle soreness. At one time, experts thought that stretching reduced the buildup of lactic acid in muscles, reducing the stiffness and soreness you feel the next day. However, the theory didn’t fit the facts. Although lactic acid causes the burning feeling you experience while you strain your muscles, it quickly disappears after exercise. Muscle soreness usually appears much later (after a day or two), when there’s little lactic acid left in the muscles. Today, biologists believe that the soreness is caused by inflammation, which sometimes follows the microscopic muscle-tearing that stimulates muscle growth.

More important than stretching after a workout is carrying out a proper cool down—gradually stepping down your exertion until your heart rate is just 10 to 15 beats above normal. Stopping too abruptly can cause a sudden drop in blood pressure and muscle cramping.

Finally, none of this is to say that stretching isn’t worthwhile—many experts believe stretching is very important for preserving flexibility and maintaining health. Good stretching regimens include yoga and tai chi, and may also involve meditation and breathing techniques that reduce stress.

The best ways to avoid muscle soreness are to keep up a regular exercise routine, avoid abruptly increasing the intensity of your workout, and give tired muscles sufficient time to recover (a day or two, depending on how much you exercise).

Source of Information : Oreilly - Your Body Missing Manual

Should Women Lift Weights?

Written by Science Knowledge on 2:11 AM

Many women avoid strength training because they’re afraid it will give them massive, Schwarzenegger-sized muscles. But while strength training might cause the number on the scale to inch up (muscle is heavier than fat, after all), it certainly won’t cause bulky muscles to burst out of your blouse. That’s because women lack the testosterone needed to fuel serious muscle growth. If you want to be a female body builder, you can give it a shot with an extremely rigorous, extremely specialized workout, but ordinary exercisers can’t get anywhere close.

So with that worry out of the way, here are some of the reasons why every woman should add strength training to her workout regimen:

• To preserve bone mass and stave off osteoporosis

• To reduce blood pressure

• To lower the risk factors for various diseases

• To create strong tendons and ligaments, thereby reducing the risk of injury from accidents or other activities

• To boost resting metabolism (the amount of calories your body burns when it’s not doing much of anything) and fight the creeping weight gain of advancing age

• To keep misbehaving men in line

Although the average woman won’t lift the same load as the average man, the strength training advice in this chapter applies equally to both sexes. That means that to get the benefits of strength training, you need to do it often enough (two or three times a week) and with the right weights (ones that are heavy enough to strain your muscles, but not so heavy that you can’t control your movement). And if you aren’t comfortable in the sweaty, testosterone-soaked atmosphere of the local gym, shop around until you find a more relaxed place that suits your style, or opt for a women-only fitness club.

Source of Information : Oreilly - Your Body Missing Manual

Building Muscles

Written by Science Knowledge on 1:09 AM

Muscle cells share one thing in common with the fat cells—they rarely multiply. The number of muscle cells you had at birth is the same number you have now. And there’s probably nothing you can do to change that.

Fortunately, you don’t need to increase the number of your muscle cells to gain strength—you simply need to beef up the ones you have. Oddly enough, the trick to building stronger muscles is to damage them, and the best tool for inflicting the gentle trauma you need is exercise.

Here’s how it works. When you exercise, the vigorous muscle contractions create microscopic tears in your muscle fibers. As your body repairs these tears, it stuffs in a bit more protein to make the muscle a little more resilient the next time. Repeat this process over the course of a year, and you have a recipe that gradually bulks up your muscle, making it stronger along the way.

Muscles don’t necessarily need to get bigger to get stronger. Studies find that exercised muscles develop a better blood supply, which gives them improved access to oxygen and lets them work longer before tiring out. They also respond more readily to the signals your brain sends them, springing into action more easily. Exercised muscle cells also get more mitochondria, which are the power plants of your body. They carry out the energy-producing chemical reactions that muscles need to contract. The net effect is that an exercised body gets a larger and more easily accessible energy supply.

There is one case when your body creates new muscle cells—if an existing muscle cell dies because of damage or disease. But this process has strict limits. For example, your body can’t repair certain types of muscle tissue or patch up extensive damage, and it may fill gaps with useless scar tissue. (This is what happens if you suffer a heart attack, in which case your heart is never the same again.)

Source of Information : Oreilly - Your Body Missing Manual

Understanding the Role of Oxygen

Written by Science Knowledge on 2:06 AM

The term aerobic exercise actually means “with oxygen.” When you perform aerobic exercise, your muscles generate the energy you need using a complex series of chemical reactions that involve oxygen. That’s also the reason your breathing speeds up (to get more oxygen) and your heart begins to race (to pump that oxygen-rich blood to the muscles that need it).

Strength training is also called anaerobic exercise, which means “without oxygen.” That’s because the processes that turn oxygen into energy don’t work fast enough to keep up with anaerobic exercise. Instead, your body makes up the difference with a different set of reactions that use the energy stored in your muscles as glycogen. These energy reserves are limited, which is why your muscles can’t sustain anaerobic exercise for long before they seize up.

Incidentally, when you do aerobic exercise, you’re primarily using your slow-twitch muscle fibers. When you do strength training, you’re putting your fast-twitch fibers to work.


Source of Information : Oreilly - Your Body Missing Manual

Exercise

Written by Science Knowledge on 2:04 AM

Muscles are the ultimate self-tuning organs. If you rely on them to perform daily labor, they respond by growing bigger and stronger. But if you don’t give them anything useful to do, they shrink. That way, your body saves on the metabolic cost of keeping them alive. After all, the more muscles you have, the more calories you burn, even at rest—and your frugal body isn’t willing to waste all that valuable fuel.

In the modern world, where the hardest labor many people do is to reach across the sofa for the TV remote, our daily activity just isn’t enough to keep our muscles healthy. To fill the gap, we created exercise—basically, a practice in which we lift heavy things and then put them down in exactly the same place, or run like crazy on a machine without actually going anywhere.

Exercise is a thoroughly modern invention. Thousands of years ago, the balance between rest and activity was almost exactly the reverse of what it is today. People spent most of their lives straining their bodies, and if they had a moment of free time, the healthiest thing they could do was rest their weary muscles. Today, we spend most of our lives sitting in one place and thinking hard (or at least trying to look like we’re thinking hard). When we have time off, we use exercise to build and maintain healthy muscles— or, from a more cynical perspective, to give the illusion that our bodies are being put to good use. But if you want to spend your twilight years strong, hearty, and with all the muscular strength you need to pull your bottom off a toilet seat, you need a regular regimen of exercise.

As you probably know, there are two basic types of exercise:

• Aerobic exercise. This is the heart-pounding, fast-breathing sort of exercise you perform when jogging, swimming, cycling, or jumping on a trampoline. A regular regimen of aerobic exercise strengthens your heart, improves your lung capacity, and increases your endurance. It has a cascade of other potentially beneficial effects on the body, too—for example, it can improve your coordination, boost your metabolism, and burn fat. However, aerobic exercise isn’t the best way to build your muscles.

• Strength training. This is the intense muscle-straining exercise you perform when lifting weights or doing sit-ups. It makes your muscles contract much more forcefully, but for much shorter periods of time. Although a regular regimen of strength training won’t improve your stamina, it will pump up your muscles.

Both types of exercise are important, and their benefits are complementary. You’ll learn more about aerobic exercise on page 172, when you explore the heart. In the following sections, you’ll learn more about how muscles develop, and you’ll get some practical tips to help with your own strength training.

Source of Information : Oreilly - Your Body Missing Manual

Caring for Your Tendons

Written by Science Knowledge on 2:28 AM

You can injure tendons with repetitive motion and excessive exercise. Any repetitive action, from swinging a golf club to practicing a piano sonata, has the potential to cause problems, including inflammation, soreness, and pain with movement, which can range from mildly bothersome to chronically agonizing.

Here are some tips to avoid the worst problems and treat your tendons with the respect they deserve:

• Go slow. People often injure their tendons when they suddenly put new demands on them—for example, trying to master a new sport in a weekend or write a five-year business plan overnight. But if you build up to a new activity slowly, your tendons will grow stronger and your body can adjust gracefully.

• Take breaks. Almost all types of repetitive stress injury occur when you work a muscle the same way for hours at a time. If you’re an office worker, take frequent pauses to stand and stretch and an hourly break to walk around the block. If you’re an athlete or fitness buff, vary your workouts, try a different sport, or go for a swim.

• If you’re injured, stop. This one is important, because if you carry on in the face of tendon pain you’ll not only prolong the suffering, you’ll increase the risk of permanent nerve damage. This is a particularly serious danger for hard-driving musicians (violinists, piano players, and so on).

• If you’re in doubt, see a doctor. If the pain persists or you have other symptoms (for example, an inability to move a part of your body properly or tingling and numbness), have it checked at your doctor’s office. Your doctor can rule out other problems and prescribe an anti-inflammatory medication that may help.

Source of Information : Oreilly - Your Body Missing Manual

Binding Muscles to Bones

Written by Science Knowledge on 1:17 AM

If you were able to dissect yourself, you’d find that most skeletal muscles attach directly to bone with a tough piece of connective tissue called a tendon. When a muscle contracts, it pulls on the tendon, moving the appropriate bone. Most skeletal muscles stretch over a joint, from one bone to another. A tendon anchors the muscle on both sides. Skeletal muscles aren’t always where you expect them to be—namely, on the body part they control. The muscles that bend your knee, for example, sit inside your thigh. Similarly, the muscles that bend your elbow are inside your upper arm.

One of the more interesting examples of this quirk is found with the muscles that move your fingers, which aren’t anywhere near your 10 digits. If they were, your fingers would be plump, clumsy little sausages. You’d need a jumbo-sized keyboard to type your name and a robot to tie your shoes, and you’d have no chance of playing any instrument requiring more manual dexterity than a plastic whistle.

Instead, the major muscles that move your fingers are in your forearm. To take a look, roll up your sleeve and watch the top of your forearm as you twiddle your fingers around. You’ll see the contractions of the finger-controlling muscles in your arm. Long tendons stretch from these muscles, down your arm and through your wrist, connecting them to your fingers.

When these muscles move, they pull the tendons and jerk your fingers around, somewhat like a puppeteer controlling a marionette. Although your hand does have a few smaller muscles that help precisely position your fingers, the muscles in your forearm hold the real power.

Right now, this fact might seem like little more than a second-rate party trick. But there’s a good reason to understand your tendons—they’re the source of many types of injury. For example, tendons that repeatedly rub against a narrow passage in your body can cause painful inflammation, called tendinitis. Tendinitis commonly involves the tendons around your knees, elbows, shoulders, or wrists.

An even more insidious wrist problem is carpal tunnel syndrome. It occurs when the tendons that control your fingers become chronically swollen and put pressure on your hand’s medial nerve. This happens because both the tendons and this nerve share the narrow passage in your wrist called the carpal tunnel.

Even more catastrophically, you can tear or cut a tendon, which will prevent you from operating the attached body part unless you see a surgeon—fast.

The 50-odd muscles in your face are unique—instead of using tendons, they connect directly to your skin. This attachment gives you remarkable control. It’s the reason your face can communicate the subtlest of emotions, while the skin on your back lacks the same expressive power.

Source of Information : Oreilly - Your Body Missing Manual

White Meat and Dark Meat

Written by Science Knowledge on 1:12 AM

Even if your body is more Bill Gates than Mr. Universe, it still boasts about 650 skeletal muscles. Each muscle is built out of long, tough fibers that are grouped into rope-like bundles. When you throw a javelin (or just lift your posterior off the couch), these fibers pull in unison, generating the force you need.

There are actually two types of fibers at work in any skeletal muscle:

• Fast-twitch. These fibers contract with brief bursts of explosive force. However, they can’t keep contracting for long. Fast twitch fibers are a light whitish color.

• Slow-twitch. These fibers contract more slowly and with less force. However, they can sustain their contraction for longer periods of time. Slow-twitch muscle fibers are reddish and darker in color than fasttwitchers because they have more mitochondria—the cellular factories that generate energy. Your muscles have a different mix of fast- and slow-twitch fibers, depending on their purpose. For example, the neck muscles you use to hold your head upright perform slow, steady work all day, so you’re likely to find that they have more slow-twitch fibers.

If you examine the muscles of elite athletes, you usually find that their mix of muscle fibers matches the requirements of their sport. In other words, the muscles of sprinters are fast-twitch white meat, while the muscles of marathon runners are slow-twitch dark meat. Much of the difference between the amount of fast-twitch and slow-twitch fiber you have is genetic. Even hard-core exercise seems unable to change your ratio of fast-twitch to slowtwitch muscle fibers. So if you’re a white-meat sort of person, all the crosstraining in the world won’t give you dark-meat muscles. But don’t shelve your gym shoes just yet. Most people have a wealth of underused muscle fibers. When you exercise, you trigger a raft of beneficial changes that alter the way your muscles work in ways both straightforward and subtle. And if you train for a particular sport, your body adapts to become more and more efficient at it. So the bottom line is this—just about anyone can develop the muscles of a proficient marathon runner, but you’ll need an extra genetic gift to become a world champion.


To let this all sink in, try reflecting over a takeout chicken. The breast meat is mostly white because it’s made up of fast-twitch fibers that (in better times) helped the chicken flap its way into the air with short bursts of contractions. The leg meat is a darker color because it’s rich in slow-twitch fibers, which the chicken used to use to amble around all day.

Source of Information : Oreilly - Your Body Missing Manual

The Three Flavors of Muscle

Written by Science Knowledge on 2:08 AM

All muscles are not created equal. In fact, your body has three very different types of muscle, each of which does a different kind of work:

• Skeletal. These are the muscles most people think of first. They’re anchored to your bones and under your conscious control. You use these muscles to move your body parts (and to impress potential dates at the gym).

• Smooth. Most of these muscles are deeper inside your body, in thin sheets that line internal passages like your digestive tract, your blood vessels, your bladder, and (if you ve got one) your uterus. You also find smooth muscles closer to the surface, where they can make the several million fine hairs on your body stand on end.

• Cardiac. You find this muscle type in just one place—your heart. Like smooth muscle, cardiac muscle is beyond conscious control, meaning you can’t will it to contract or stop contracting. However, the structure of cardiac muscle is more similar to skeletal muscle than to smooth muscle, and its uncanny sense of rhythm is something no other muscle can match.

Source of Information : Oreilly - Your Body Missing Manual


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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