Muscles are amazing; without muscles you would be nothing more than a pile of immobile tissue, bone and fluid. Muscles control movement but they also do a whole lot more than that.
You use them every day, they power your every move, but you probably know (or remember) little about them. You want them to grow stronger, bigger, faster. So, perhaps a little background is in order. After all, information is power and if you understand them better, you can train them better and ergo, get better results.
You have over 600 muscles in your body. Their names normally come from Greek or Latin and often describe the location, orientation or function of the muscle in question.
For example, your biceps brachii is the two-headed muscle on the front of your arm – brachii meaning arm and bi meaning two. If you know a little Latin (and a lot of anatomy), you can make up the rest.
Muscle is responsible for all movement, they hold you up against the pull of gravity, they provide padding from impact, they are where we store some of our fuel reserves, they produce heat when we are cold by shivering, and can also provide fuel if food is scarce.
Types of Muscle
There are three types of muscle tissue:
- Skeletal muscle is responsible for movement and is attached to your bones via tendons.
- Cardiac muscle is heart muscle.
- Smooth muscle is found in your digestive and circulatory system. Your blood vessels are a good example of smooth muscle tissue.
Types of skeletal muscle fiber:
- Type 1 muscle fibers are predominately aerobic fibers which are good for generating low levels of strength for a long time (i.e. endurance).
- Type 2b fibers are anaerobic fibers that are good for generating high levels of strength but for a short time (e.g. sprinting).
- Type 2a muscle fibers are much like 2b fibers but will also act like type 1 fibers if trained appropriately. This is why they are sometimes called intermediate fibers while type 1s are called slow twitch and 2bs are called fast twitch fibers.
Your ratio of fast to slow twitch fibers is genetic and helps explain why some people are better at certain activities than others – despite training.
For example, if you have an abundance of type 1 muscle fibers, you are very well equipped for endurance sports such as marathon running. If, however, you are more of a type 2b person, you will be better at power and strength activities such as football or weight lifting.
Because of trainability, you can always improve either your strength or your endurance but your genetics will ultimately play a role in how good you can get.
And then there’s something called fascia. Muscles are wrapped in a gauze-like sheath of connective tissue called fascia. This keeps your muscles separate so that they can contract and relax independently. Like muscles, fascia also contracts and stretches and can also feel pain.
Exercise & Muscles
Muscles can generate force in three ways – as they shorten, as they lengthen and while staying the same length. These types of contractions are called concentric (most people think of this as a muscle contraction), eccentric and isometric respectively.
Muscles are generally arranged in pairs on opposite sides of joints and are attached to your bones by connective tissue called tendons. Muscles can only pull – they cannot push. Pushing-type movements like push-ups are actually the result of your muscles pulling your limbs straight.
In every movement that occurs, your muscles have different jobs or roles. The muscle responsible for the majority of the movement is called the agonist or prime mover while the muscle on the opposite side of the same joint is called the antagonist. When the agonist contracts, the antagonist must relax to allow movement to occur.
Synergists, smaller, nearby muscles, give assistance to the agonist while fixators hold your nearby joints and limbs steady so that the agonist has a stable platform to work from.
Here’s an example of the roles your muscles play in the push-up exercise:
- Agonist – pectoralis major (chest muscles) are doing the majority of the work.
- Antagonists – medial trapezius and rhomboids (upper back) relax to allow movement to occur.
- Synergists – anterior deltoids and triceps (front of shoulders and back of arms) help the chest.
- Fixators – rectus abdominus and rotator cuff (abs and deep shoulder muscles) keep your spine stiff and your shoulders stable for safe push-up performance.
Types of Muscle Growth
Muscles get bigger as a result of exercise but there are two proven mechanisms for muscle growth and a third that has yet to be conclusively proven.
An increase in thickness of the actin and myosin is called sarcomere hypertrophy and is also known as functional hypertrophy. This just means that as your muscles get bigger, they get stronger too. Sarcomere hypertrophy is commonly associated with lifting heavy weights and low repetitions.
This is in contrast to sarcoplasmic hypertrophy which describes how muscles get bigger because of the accumulation of intercellular fluid. This is also known as non-functional hypertrophy as it is not associated with any increases in strength. Sarcoplasmic hypertrophy is more associated with moderate weights and a high volume of exercise.
This is the reason bodybuilders usually do both forms of training and are usually bigger, although often not as strong, as weight lifters who predominantly focus on heavy weights in their training.
Some evidence suggests that muscle cells can split, reproduce and increase in number – this is called hyperplasia although this is not confirmed in humans.
You Can Lose Muscle
The opposite of hypertrophy is muscle atrophy which is the term used to describe muscle shrinkage.
Muscle is a “use it or lose it” type of tissue and if you don’t live an active life that periodically stresses your muscles, your muscles will respond by getting smaller and weaker. This is especially true after you hit your 40s.
For this reason, strength training is especially important for middle age exercisers.
Post-Workout Muscle Soreness
If your muscles hurt after a workout, you probably have delayed onset muscle soreness or DOMS for short.
The exact mechanisms that cause DOMS is unclear but lactic acid, waste products from metabolic processes and muscle fiber micro trauma are thought to be the main suspects. While the mechanics of DOMS may in dispute, we do know that it is triggered by unusually heavy exercise or a novel workout.
Eccentric exercise (when the muscle is lengthening) is more likely to trigger DOMS than concentric exercise (when the muscle is shortening). Contrary to popular belief, DOMS does not necessarily mean you have had a productive workout. Rather, it means you have done something that is new or unusual.
Mild DOMS is nothing to worry about, but DOMS so severe that you are incapacitated suggests you have done too much exercise too soon.
To keep your muscles fit and strong, you need to exercise regularly, both cardio and strength training, drink plenty of water, eat a balanced diet and stretch often enough to maintain flexibility. By doing these things you can ensure your muscles will stay in tip-top shape.
