posted on May 21, 2020
The body is fascinating. I am typing this and eating almonds, and despite being extremely sedentary, my body is still working. Clearly not difficult work but there are still jobs to be done, like keeping myself in good posture, engaging my fingers to type, and digesting my food. Although the intricacies may not excite everyone, I believe there is benefit for those who invest a certain amount of time and energy into transforming the body to understand an overview of its efforts.
I will continue to dive in a bit deeper to specific muscles and their role, provide a few tips for relieving pain without a massage, and similar topics that pop into my head or that you request. The thought of summarizing something so complex seems daunting, but my hope is that if you know nothing about the body you learn something and if you know it all you are reminded that the body is neat. Let’s get to it.
The muscular system consists of skeletal, cardiac, and smooth muscle cells. Cardiac and smooth muscles are part of the autonomic nervous system and work involuntarily. Cardiac muscle cells are found in the heart and smooth muscle cells line the walls in hollow organs such as the stomach and passageways such as arteries. In the skin these cells cause your hair to stand up when you are cold or scared, aka goosebumps. Skeletal muscle cells are under voluntary control of the somatic nervous system and are composed of bundles of cells called muscle fibers. Muscle fibers are composed of many myofibrils which contain sarcomeres. These are the block-like units that appear adjacently down the entire myofibril and each have alternating thick filaments (myosin) and thin filaments (actin). The myosin latches onto the actin pulling it so the proteins slide past each other. This causes the sarcomere to shorten thus creating a muscle contraction, known as the sliding filament mechanism.
I’m going to stop there with the actual contraction of muscles. I hope that gave you a glimpse of the internal happenings of muscle cells, but now I want to introduce something a little less #science-like and a bit more practical if you want to get the most out of training.
If you have worked with any of our coaches or trainers, I am sure you have heard the terms isometric, eccentric, and concentric contractions. I would like to bet they even taught you the meaning and benefit of each. But, if you haven’t used them yet or don’t quite get it, let’s take a peek now.
Isometric: the muscle fibers do not change length during contraction. Examples are exercises with a pause or a plank. Training isometrics are beneficial because they require you to maintain the proper position even when you are “on the breaks”.
Eccentric: the muscle fibers lengthen during this phase. An easier way to think of it is the part of the movement when your body wants to accelerate. Lowering the arm from a biceps curl, the downward motion of the squat, or the upward phase on the leg curl machine are a few examples. Training this phase of the movement can be done with negatives, or slow eccentrics, by using a count to slow the movement down. This is helpful for maintaining tension even when you are “stepping on the breaks” and for beginners learning the movement. Oftentimes, the eccentric phase will be prescribed for rehab exercises, although they do not always need to be slow reps.
Concentric: the muscle fibers shorten, creating the force to move an object. If training speed work, it is performed during this portion of the movement as we “step on the gas”. Examples are the upward portion of the biceps curl, standing up from a squat, and pulling yourself up during a pull-up.
Have you ever wondered why muscles received their name? Most are very easy to figure out and can be helpful during training. Muscles are named for a variety of reasons but here a few of the most interesting:
Arrangement of the muscle fibers: the fibers run lengthwise through the muscle and can be named dependent on their direction. Example: the deltoid is rounded and triangular on the shoulder. The transversus abdominis is the deepest abdominal muscle that runs horizontally across the abdomen. Knowing the direction of the fibers can help guide you in the action of that muscle and exercises to target it best.
Number of origins: The origin of a muscle is the attachment site that does not move and some have more than one. You might be able to guess. The (bi)ceps with the long and short head; the (tri)ceps with the long, medial, and lateral heads; and the (quad)riceps with four parts named the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. This can be helpful because although we typically group the three heads of the triceps into one word, each section can be targeted better through different movements. If you want bigger or more useful muscles, it helps to make them well rounded.
Location of origins and insertions: insertions are the movable attachments. An example of this is the sternocleidomastoid, a neck muscle that originates on the sternum and inserts on the mastoid (a part of the temporal bone near the ear). With any muscle, the insertion is pulled toward the origin when a muscle contracts, which can help guide you to the movement of the muscle.
Size of the muscle: examples are the gluteus maximus (the largest muscle in the body) or the extensor digiti minimi (the muscle that extends the pinky finger).
They can also be named for their action, but instead of listing a few examples I want to talk about those actions.
Flexion: a movement that decreases the joint angle (think biceps curl as you bring your wrist closer to your shoulder or hip flexion as you bring your knee closer to your chest).
Extension: a movement that increases the joint angle (think triceps extension as you straighten your arm or hip extension as you bring your hips through in a bridge).
Abduction: a movement that brings a limb away from the body (clamshells, side steps, or lateral raises). Adduction: a movement that brings the limb close to the body (return from abduction or cable crossover).
Elevation: a movement in the upward direction (shrugging).
Depression: return from upward movement.
Rotation: think rotator cuff exercises such as internal rotation and external rotation.
Performing any of the above actions will consist of the primary mover, the opposing muscle, and the helpers – and they all have special names. I will use the classic bicep curl as an example. The bicep, which is the muscle on the front of the arm performs elbow flexion, so it is the agonist; however, the triceps which is the muscle on the back of the arm performs elbow extension, so it is the antagonist in this situation. The brachioradialis and brachialis, two forearm muscles help the biceps move through elbow flexion so they are called synergists. I will redefine as needed again, but I will most certainly use these terms in the next few blogs.
Well, that covered a lot and very little all at the same time. The body is complex and it can seem overwhelming, but knowing even a little can make it seem less arduous. I encourage you to learn more about the body and here is my recommendation: each day you train, take a few minutes to search the exercises you plan to do and answer a few questions. What muscles are used during the movement? What are the actions? What is the antagonist and synergist of the agonist? If you are extra curious, read more, ask any of us your questions, and continue to learn. The more you know, the more effective your time in the gym will become, which is always valuable. 🙂