The Human Movement System In Fitness

When most people think about the human movement system in fitness, they think about the muscular system first. This is because most people train the body to see changes in muscle. However, the systems responsible for human movement include an interplay between three primary systems:

• Nervous system
• Muscular system
• Skeletal system

This complex system is important for the likes of a physical therapist, certified personal trainer, and certified athletic trainer. However, it’s important to know how human movement occurs for anyone who exercises or cares about fitness. For the body to move (or have a reason for movement), a  signal has to be sent from the brain to initiate a muscle contraction. Then, the muscle contracts and pulls on bones of the skeletal system to produce movement during exercise. The nervous system then receives feedback about how the body is moving and what needs to happen next. Therefore, locomotion is part of a continuous loop. This is especially important to know in fitness because it increases the emphasis of the nervous system on human movement.

Nervous System

This system is the central command center of the body. It consists of the central and peripheral nervous systems (CNS and PNS respectively). The CNS includes the brain and the spinal cord. Whereas the PNS includes all the neurons sending and receiving messages to the rest of the body. The brain is where motor control, motor learning, and motor development occur and produce skilled, voluntary movement over time. 

Neurons, or nerve cells, spread everywhere in the body. There are two types: the efferent neuron and the afferent. The efferent neuron transmit nerve impulses to “effector sites”, in the example of exercise, to skeletal muscle. The afferent neuron, on the other hand, is a sensory receptor. In fitness, the most important type of sensory receptor is a mechanoreceptor.

Mechanoreceptors are important because they sense touch, pressure, motion, and stretch. If you were to close your eyes and pick up a weight, these receptors would provide information to the brain. They would transmit information to your brain such as how heavy the weight is, how stable it is in your hand, and more. This info then helps your brain make decisions about how to respond. For example, if it’s a 10 pound weight the muscles will have to contract with far less force than if it’s a 100 pound weight. And, if it is a 100 pound weight, your body will have to counterbalance and help you lift it off the ground so you don’t fall over.

To put this as simply as possible, the NS determines:

• Speed of muscle contraction (power training)
• Amount of muscle contraction (strength training)
• Length of muscle stretch (flexibility training)
• Spatial and environmental needs (balance training)

Muscular System

Next in the discussion of human movement science is the muscular system. This system consists of two distinct types of muscle fibers. These include Type I and Type II muscle fiber types. Type I fibers, or slow twitch fibers, have more capillaries and oxygen around them. Therefore, this is the muscle fiber type working during physical activity that’s long in duration, or aerobic exercise. Type II fibers, or fast twitch, produce more speed and power muscle contractions. You can think of the difference as simple as running a marathon versus a 100m sprint.

After a nerve impulse, a muscle will contract and pull on the skeletal system via connective tissue (tendons). However, a muscle can serve different functions in human movement. A muscle can:

• Do most of the work to move (prime mover or agonist)
• Assist a larger muscle to do the movement (synergist)
• Stabilize joints to make a solid foundation (stabilizer)
• Lengthen out to allow more movement (antagonist)

This is good to know in fitness because sometimes a muscle will be serving the wrong role. For example, a smaller muscle that should assist the larger muscle might take up extra work if the larger muscle can’t do the job. This can cause movement impairments (when the body isn’t moving the way it naturally should). Movement impairments, or muscle dysfunctions, can happen for several reasons. More importantly is to know that bad movement patterns can happen on a small or large scale. And, even on a small scale can cause problems because they pull the joints and bones into unintended motions.

Another issue can happen when the stabilizers don’t fire. Stabilizer muscles are smaller and produce less visible movement. Therefore, people tend to overlook them. A perfect example includes the rotator cuff muscles of the shoulder. Exercisers often lift heavy weights to get stronger or grow more muscle. A common exercise among weightlifters is the bench press. Similarly, athletic training requires speed and power in sports like baseball, basketball, and golf. If the shoulder doesn’t have good stability, then forces don’t distribute correctly to the rest of the body parts. In this instance, weak rotator cuff muscles can result in shoulder pain and even injury. Knowing the anatomy of a chest press, will help you realize what muscles play which role. And, ultimately, you’ll perform your workout better and with less risk of injury.

Of course, pain and injury are only in the scope of medical professionals like doctors and physical therapists. However, personal trainers who have a strong understanding of biomechanics and kinesiology can become movement experts. 

Skeletal System

This rigid system provides structure and a framework for the body. It has two divisions consisting of different types of bones and joints. The appendicular skeletal system includes the skull, sternum and ribs. It also includes the lumbar, thoracic, and cervical spine as well as the sacrum and coccyx (tail bone). The appendicular skeletal system, on the other hand, includes over 120 bones of the upper extremity and lower extremity. Muscles attach to bone through tendons and bones attach to bone through another connective tissue, ligaments.

There are also sensory receptors in the joints, joint receptors. As the body begins to move, they provide information to the brain about joint angle, pressure, and more to protect the body. However, in the case of faulty movement patterns, the joints will move in ways they shouldn’t. This can cause inflammation, pain, and, over time, injury, if the movement doesn’t correct.

Human movement science is a part of any fitness professional’s training. And, professionals can find these impairments during a comprehensive fitness assessment. Fitness assessments should never provide medical diagnoses. Instead, they evaluate visible movement and aim to correct it.

You can learn more about human movement, biomechanics, and developing effective fitness programs as an EMAC Certified Personal Trainer. Learn more about our online programs and take your fitness to the next level today!