Muscle Anatomy: Endurance, Power, Flexibility
I truly believe that a good knowledge and understanding of how your body works will determine how well you train. It will contribute to injury prevention as well as gains in endurance, strength, power, and flexibility. Endurance is how long your muscles/body can be at work. Strength is the amount of work your muscles can do. Power is a combination of strength, force, and speed . Flexibility is the ability to lengthen your muscles to their full extent. Aerialists need to train their body for all of these abilities in order to become successful. I will write posts on training each of these aspects and more, but let's first take a look at how the muscle does these things.
There are a few different types of muscle, however the muscle we will be talking about today is skeletal muscle. Skeletal muscle is a striated muscle tissue that is controlled by the somatic nervous system, meaning that we voluntarily control our skeletal muscles (unlike the heart which is a muscle controlled by the autonomic nervous system). The muscle tissue is made up of several components that form together as muscle cells, or fibres. One of the ways in which to classify muscle fibres is on their "twitch" speed. This is basically how fast the muscle can create ATP (adenosine triphosphate, muscle energy) from various resources (nutrients such as carbs, fat, etc) . There are two ways that muscles can produce ATP; Aerobic (with oxygen) and Anaerobic (without oxygen). Our cells prefer to create ATP with the presence of oxygen to fuel metabolism, however the increased intensity of exercise will use oxygen faster than our bodies can deliver it, thus increasing the need for other resources. Unlike Aerobic metabolism, anaerobic metabolism is not sustainable for long periods of time and the muscles become fatigued and produce chemical waste (lactic acid) which causes that burning sensation during intense exercise.
So, fast twitch muscles use mainly Anaerobic metabolism, while slow twitch muscles use mainly Aerobic metabolism. Everyone has approximately a 50/50 split of fast and slow twitch muscle fibres. If you are naturally good at sprinting vs long distance running, you may have slightly more fast twitch muscles. Fast twitch would be preferable for athletes who need quick bursts of power but do not need the endurance, while slow twitch muscles would be preferred by athletes who need to endure long periods of muscle contraction but may not need their muscles to contract quickly. In aerial arts we use a good combination of both slow and fast twitch muscle fibres.
So, now you understand how muscle fibres use different methods to create energy, and how that type of method can be applied in different athletic settings. But how exactly does a muscle contract?
Your brain sends a signal to the nerves in your muscles to contract. There are tension generating cells within your muscle fibres that cause the contraction. Contracting a muscle can be isometric (producing tension without changing in size) or isotonic (producing tension and changing in size). An example of isometric contraction would be holding a plank position. You are creating muscle tension to hold yourself up, but your muscles are neither shortening or lengthening. Isotonic contraction would be when you move from holding a plank to doing a pushup, and your muscles start to lengthen and shorten to create that movement in your body.
There are sensory receptors in your muscle fibres called muscle spindles. The spindles run parallel with the muscle fibre, and are in charge of telling your body what position your muscle is currently in. Is it shortened? Is it lengthened? Your spindles send this information to your brain via your nervous system. This information helps you determine where exactly your body is in space. The spindles also play an important role in muscle flexibility, as they activate motoneurons that contract the muscle in order to resist muscle stretch to prevent injury. If you are not a very flexible person, this means that your muscle spindles are trying to protect your muscle by not allowing it to lengthen in a stretch reflex. You can condition the spindles to allow lengthening through chronic stretching, thus increasing your flexibility. Some people are naturally more flexible than others and some people must work for it.
As I mentioned earlier in this post, your muscles need to produce ATP, or, energy. You need to provide your muscles with the appropriate fuel (food!) in order to make this happen. Carbohydrates are the body's preferred source of energy, (and your brain's ONLY source!) . Carbs are broken down into glucose which is further used to produce ATP. This is especially important in Anaerobic metabolism when there is no oxygen present.
Diets such as the Atkins diet are founded on the idea that without many carbs for your body to use as fuel, your cells must turn to create energy from fats (ketosis) , however this process is less efficient at creating adequate energy, and can mess with your metabolism creating a whole host of problems.
Healthy carbs are essential in everyone's diet. Potatoes (baked or steamed), raw veggies like carrots, green peas, bananas and other fresh fruits, and whole grains are all great examples of healthy carbs that provide your body with lots of fuel for being active. It is also very important to eat healthy fats in moderation such as avocado, nuts and seeds, etc. And for rebuilding that fatigued muscle? Protein! You can get more than enough protein from eating plants such as nuts and seeds, legumes, grains, and vegetables. If you want to throw some healthy animal protein, try omega-3 rich fish such as salmon. I don't personally advocate eating other animal proteins as many studies have linked consuming meat (especially red/processed meat) with cancer and other diseases. Not to mention the ethics of current meat production (environmental destruction, world hunger, hormones, antibiotics, mistreatment of animals etc).
I hope this article has given you a thorough understanding of the muscle, how it works, and gets you to start thinking about how you can train smarter.
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