Understanding Muscle Growth
Knowledge is power, and understanding the way your body works on a biological level can help you workout smarter instead of just harder. Muscle growth is the goal of any strength training workout, and knowing how your muscles grow and adapt to stress can help you create the more effective routine for you.
The skeletal muscles in the human body contract when they receive signals from motor neurons, so the better you become at having those signals tell your muscles to contract, the stronger you can become. This is why a powerlifter can lift very heavy weight despite not looking very muscular, it’s due to their ability to activate those motor neurons and contract their muscles better than the average person. This motor unit recruitment also explains muscle memory, or why, after practice, certain movements become easier to perform and also why muscle growth appears to happen more quickly when you are just starting out lifting, and becomes more steady the more seasoned you become.
After you work out, your body repairs or replaces damaged muscle fibers by fusing them together to form new muscle protein strands, called myofibrils. These repaired myofibrils are thicker and more in number to create muscle hypertrophy, or growth. Muscle growth only occurs when this rate of muscle protein synthesis is greater than the rate of muscle protein breakdown, which is the damage done during your workout, which is why rest is so important for your muscles to grow.
There are 3 ways to create the stress that elicits muscle growth: through muscle tension, muscle damage and metabolic stress, although all three usually work together.
Muscle tension: In order to produce muscle growth, you have to apply a load of stress greater than what your muscles have already adapted to, ie. lift progressively heavier weights. You can also create more muscle tension through manipulating other variables like number of reps and speed of movement.
Muscle damage: You've probably felt muscle soreness before, and if you have, you have experienced muscle damage. The soreness is a defense mechanism to get you to rest the area to avoid further breakdown while your body works to repair it. You do not have to feel soreness for there to be muscle damage, however, so don't use that as your only ruler.
Metabolic stress: More commonly referred to as "the pump", metabolic stress causes swelling in the cells, which helps to contribute to muscle growth without necessarily increasing the size of the muscle cells. This type of growth is known as sarcoplasmic hypertrophy and is one of the ways that people can get the appearance of larger muscles without any increases in strength. Simply put: pounding out a few pushups before you take your shirt off can make your muscles look bigger.
No matter what you do, however, your hormones rule muscle growth because they regulate all activity in your cells. Testosterone is the main hormone for building muscle because it increases protein synthesis, inhibits protein breakdown, and stimulates the production of other anabolic hormones. Although most testosterone is bound in the body and not available for use, strength training can release release more testosterone, but also make the receptors in your muscle cells more sensitive to any testosterone loose in your system.
Muscle hypertrophy takes time and is a relatively slow process because of the constant tear down needed for it to occur. For most people, visible hypertrophy can take several weeks or months.
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