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How Does Muscles Increase

How Does Muscles Increase


Fifty years ago, the physiology of muscle hypertrophy (growth) was a mystery. A common perception among many athletes and coaches was that training turns fat into muscle. Scientists didn’t have the tools to study muscle growth; the technology wasn’t available. That changed in the 1960s and ‘70s- the development of the electron microscope, muscle biopsy techniques and radioactive tracers allowed scientists to look inside the muscle. Now, we know that increasing muscle strength and size involves turning on special genes to manufacture new muscle tissue and training the nervous system to better coordinate and regulate muscle force.

We understand how muscles get larger and have effective techniques for gaining muscle mass with less risk of injury and over-training.How the Body Builds MuscleAbout 20 percent of muscle is protein- the rest is water. Muscles are made up of individual muscle cells connected in bundles. Muscle fibers contain sub-units called myofibrils that are further divided into myofilaments (actin and myosin) that slide across each other to cause muscle contraction. One of the goals of your weight-training program should be to increase the size of muscle fibers by increasing the number of myofibrils, a process called hypertrophy. Most studies show that weight training increases fiber size- not fiber number. Muscle size and strength are directly related- the larger the muscle, the greater its strength.

Cell structures called genes regulate protein synthesis. In muscle, genes control the kind and amounts of proteins the cells make. Also, they control the rate that proteins break down. There is even a gene (myostatin) that prevents muscles from getting too large. Muscles get bigger by increasing the number of myofibrils. In other words, muscles increase in size by adding protein. As muscles add myofibrils, strength increases. The more myofibrils added to the muscle, the greater the increase in strength. Also, muscles get denser with training because the fiber alignment inside the muscles gets steeper.Protein synthesis. The muscle cell nucleus is the control center for protein production. Muscle cells have many nuclei, so they have a high capacity to produce new proteins. Proteins are made from amino acids on cell structures called ribosomes. The nucleus sends a message to the ribosomes telling them exactly how to arrange the amino acids to form a specific protein. The cells manufacture other proteins, such as enzymes. Enzymes play important roles in cell function and physical performance. Many factors influence protein production in muscle, including muscle tension, hormones, amino acid availability and diet.

Muscle tension. Muscle tension is the most important factor in making muscle fibers larger. Muscle tension developed during intense weight training exercise turns on cell receptors (called force sensitive-responsive elements) that trigger the genes to manufacture new muscle protein. Tension also triggers the cells to move more amino acids inside the cell membrane. The faster amino acids move into the muscle, the greater the rate of protein synthesis. In other words, muscle tension stimulates the genes to make new proteins and helps supply the amino acids to carry out the process. The major principle of making muscles big is simple: Load muscles as intensely and for as long as you can without causing injury.

Muscle fiber contraction speed (myosin isoforms). Muscle cells cause contraction when the myosin filaments bind and release from actin filaments. Scientists, such as Ken Baldwin from the University of California, Irvine, discovered that some myosin filaments move faster than others. The different varieties of myosin are called isoforms. Myosin becomes slower with any kind of training- this slows the rate that muscles contract. Weight training, for example, changes the fastest myosin isoforms into slower ones. Endurance exercise, such as jogging, makes the myosin even slower. Muscles improve efficiency when they slow down myosin cycling rates- they can produce more force with less effort. This adaptation is much like the lower heart rate you get with improved fitness- the heart pumps more blood with a lower heart rate, so the heart doesn’t have to work as hard. Likewise, fitness allows the muscles to produce more force with less work.

Anabolic hormones. The most important hormones that build muscle tissue include growth hormone, insulin-like growth factor (IGF-1), testosterone and insulin. These trigger the genes to increase protein synthesis and let more amino acids into the cells.
Hormones and muscle tension have independent effects on the genes. High doses of testosterone will trigger increases in muscle size in people, even if they don’t lift weights. Insulin also speeds the movement of amino acids into muscle cells. Most amino acids enter muscle cells via a process called the sodium pump. Insulin speeds the action of the sodium pump and increases the rate of amino acid transport into the cell. This is critical for muscle growth- the more amino acids transported into the muscle cell, the greater the rate of muscle hypertrophy. Anabolic hormones work together. For example, taking large doses of testosterone will boost the amount of the muscle-building hormone IGF-1. You get a double whammy- both testosterone and IGF-1 boost muscle size.

Catabolic hormones. Corticosteroids and thyroid hormone- produced by the adrenal glands and thyroid gland, respectively- break down protein. Blood levels of these hormones increase during times of stress or tissue inflammation. They increase after a hard workout or during periods of overtraining. When you have over-trained, your blood level of these hormones will rise and your level of testosterone will fall. You are in a catabolic state- gains in muscle size are impossible. One of the effects of anabolic steroids may be to block the action of corticosteroids, which prevents muscle breakdown and speeds recovery after intense workouts.

Protein in the diet: Optimal amino acid transport requires an adequate concentration of amino acids in the blood and muscles. Usually, this is not a problem. Most athletes take in more than enough protein in their diets to supply their muscles’ growth needs. During times of heavy training, extensive soft tissue injury, or overtraining, amino acid concentration may not be adequate. Energy intake is also important. If you do not take in enough calories, your body will break down its structural proteins for energy.
Timing high-protein meals is critical for muscle hypertrophy. Recent studies show that taking a protein supplement before you exercise will speed protein synthesis and muscle hypertrophy. During weight training, your muscles get flooded with blood. This blood helps saturate the muscles with amino acids, which helps your muscles grow. Get in the habit of taking a protein supplement before you train. This technique works; do it consistently and you will make faster gains in muscle size.

The “ups and downs” of training. As any active person can tell you, training does not lead to continuous gains in fitness or muscle size. Muscle size increases for a while, then levels off, and sometimes regresses. One reason for this is protein turnover- the constant buildup and breakdown of structural proteins. If you provide the optimal training environment for the muscles (i.e., good muscle tension during training and ideal concentrations of anabolic hormones and amino acids), then your muscles will tend to grow. You are in an anabolic or growing phase. If training and nutritional considerations are not optimal, then training gains will be less, or you may actually lose ground.
The goal of your training program should be to stay anabolic and avoid catabolic downturns. Optimize tension in your workout by using cycles. Intense workouts increase muscle size. However, you must be adequately rested to train intensely. If you exhaust yourself every time you go into the weight room, you will never recover enough to train hard. On the other hand, muscles grow best when you load them significantly for a long time. So, you must balance exhaustive training with rest. Quality of the training stimulus is the key to maximizing protein synthesis in muscle. Design your program so you set yourself up for intense workouts.

Using Science to Build Bigger Muscles
The key to promoting hypertrophy is to load the muscles with high-tension exercise, provide adequate nutrients, optimize anabolic hormone levels and don’t overtrain.

  • Your goal as a bodybuilder is to increase muscle size- not to power clean or bench press big weights, hit a tennis ball further, or run faster. Focus on muscle tension in your workouts. Do multiple sets of eight to 12 reps and push yourself. Muscles hypertrophy in response to high tension that’s applied for a long time. As Arnold said in his first movie Stay Hungry, “You must burn to grow.”
  • Muscles won’t grow if they don’t have enough protein and calories available. Eat about 1.5 grams of protein per kilogram body weight per day. Timing is important- drink a high protein shake containing about 50 grams of protein before you lift. This makes the amino acids from the proteins available for muscle growth. Weight training increases muscle blood flow. Taking the supplement before you train will ensure that plenty of amino acids reach the muscles. Also, immediately after training, take a protein/carb drink, which can enhance recovery and promote a more anabolic hormonal environment in muscle.
  • Anabolic hormones promote growth. If you don’t take steroids, maximize your natural testosterone and growth hormone levels by eating a well-balanced diet containing adequate amounts of protein, and get plenty of rest. If you choose to use anabolic steroids, take enough so that you exceed natural levels of the hormone. Your testosterone system shuts down when you take steroids, which will leave you with only low levels of expensive store-bought testosterone in your blood if you don’t take enough.
  • Include rest in your program. Muscles grow during recovery. If you don’t take time to recover, your muscles won’t grow enough and you will be so tired that you won’t be able to train hard during your next workout. Don’t rest too much- tension and hard work are the keys to building large muscles.

There is no best training program for everyone, but there is an optimal program for you. Experiment with different training methods and diets, but make sure your bodybuilding program contains the basic factors that create hypertrophy – muscle tension, calories, protein, hormones and adequate rest.

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