How do muscles move?

There are two types of signals between your nervous system (brain, central nervous system) and your muscles.

The first signal is the one that is carried from the brain down to your muscles (efferent messages). The direct pathways (pyramidal) are responsible for precise voluntary movements. In other words, your central nervous system through the brain and the spinal cord connects to your Peripheral Nervous system (the body) through the somatic nervous system division (voluntary movement) and makes the body move.

These messages are carried on by the neurotransmitters. The most important neurotransmitters that will be affected by physical activity (walking with a certain pace) are: serotonin (exercise will raise serotonin levels and help fight depression), dopamine (exercise increases both your levels and the number of dopamine receptors in your brain, dopamine is a neurotransmitter involved with muscular activity,), Norephinerine and epinephrine, The effects of walking or exercising with a certain pace (aerobically) may lower blood pressure partly involve the effects of two hormones, epinephrine and norepinephrine.

The second signal has to do with what many doctors are referring to as our sixth sense called PROPRIOCEPTION. We have receptors in our joints that are sending information up to the brain and the nervous system (afferent messages) This proprioceptors will inform the nervous system what is our body position in space. We can see this fascinating process when we are walking in a rocky beach,(we have to be very careful of where we place our joints or otherwise we will fall) or in the park, or in the street.

Minute 2 The brain starts functioning full speed. The motor cortex starts the voluntary movement to move the body. The Cerebellum is a Coordination and Headquarters for Muscular Activity, specially walking. Once that the body is moving, there are a lot of several actions happening at once such as coordination (the left leg will be coordinating with the right arm), balance (once you advance your body will be in imbalance, so proprioceptors are very important).

Therefore, regarding the brain. Not only the motor cortex will be involved with the movement but other parts of the brain as well. The part we are referring to is the cerebellum. The cerebellum coordinates input from the sensory organs of proprioception located in the soft tissues ensuring that intention and actual movement are the same. Therefore the cerebellum executes the movement with precision. The cerebellum holds 50 billion neurons (out of 100 bn neurons in the total brain) and its main functions are; balance, coordinated movement, proper postural alignment, muscle timing or cognitive learning).

Minute 5 Once that the body has started moving for few minutes, more blood kicks in the bloodstream. The more blood in the bloodstream the more stress hormones will get involved.

By minute 6, your stress hormones (epinephrine and norepinephrine) have increased in the bloodstream. These hormones are secreted from the adrenal gland and function to aid the cardiovascular system in getting blood, oxygen and nutrients to the muscles and to increase the availability of fat and glucose to the muscles for energy production.

Minute 7In this we really need to consider different scenarios:

Low-Moderate Intensity: Lets speak about the benefits from different scenarios.

- We walk slow (with our grand mother); our heart rate barely rises staying an average of 30-50% of our maximum heart rate. Maximum heart rate calculated as the universal formula of 220-age

Heart rate calculation: - Moderate Intensity. We walk little faster. Our heart rate will rise up to 50% of its maximum heart rate meaning that more blood will be required by the muscles to do the movement.

BENEFITS:- Oxygen will be required. Our lungs need to process more oxygen and spread it out throughout the entire body. However what is more important is that we will be staying in the aerobic hear rate range. What does that mean? Is that more calories will be burnt.

The main source of energy will be fatty acids since it is a low oxidative source of energy). I would recommend staying in this range. That will eventually lead to build a fitter hear (expansion of the heart size through aerobic training)

Higher Intensity: We walk really fast. Our heart rate rises up to 75% of the maximum heart rate range meaning that we leave the aerobic frontier and start getting into the anaerobic frontier. The difference between both of them is the presence of oxygen (aerobic) or absence (anaerobic). In this case, body will start producing ATP-Creatine and will require a breakdown of lactic acids. This process can last no more than 20 seconds, and then your body will start getting back to its sustainable rhythm.

EFFECTS of High Intensity Exercise:increase of the stress hormone, cortisol (catabolic), reduction of immune cell function, increase of Increase of secretion of Neurotransmitters (epinephrine and norepinephrine)

Minute 8 Lets imagine we follow the second scenario (recommended). After the eight minute the whole motor system will show how efficient it is. This means that if your motor system is efficient you will not compensate with other muscle groups and also you will not have a bad posture while walking. In the case of lack of efficiency you will see different phenomena such as bad posture, neck tilt forward, the lower back pushes in creating a pronounced arch, there will be more obvious feet or knee pronation and also there will be a lack of neuromuscular efficiency in the hip-knee ankle joint.

Minute 10 It will be very unusual that the reader will follow a complete flat surface. The more normal is that the reader will experience different levels of obstacles such as small hills. That small hill will have a direct effect on your cardiovascular system through an increase of blood into your bloodstream producing a rise in few beats in a short period of time. After going through that stage your body will either recover once it has an easier surface. In addition all the propioceptors will keep sending messages to your nervous system. You might see other people, traffic lights, runners that will produce an immediate response of accelerating or decelerating your speed.

Minute 13 Once reached half of the goal it is very important to observe how the body moves. The muscles keep requiring oxygen and you can measure very well the physical strength of an individual. People that lack physical endurance will start compensating different muscle groups observing a slight different posture than when they started. This is caused by an unequal distribution of muscle fibers. Fibers type II is associated with endurance so you can observe where the individual will need additional help to increase their strength-training program.

Minute 15The gravity center or core strength will be a good measurement of an individual’s physical strength. People with powerful core strength will keep walking steady maintaining a correct form when walking. In addition with all the changes in the surface…such as hill or other obstacles we will see if our client modifies his form in any of the major muscle groups or joints.

Minute 17Coordination will be key in this part of the walk. Once that the muscles start to experience fatigue, coordination becomes crucial. People with a lack of coordination will start to fail to maintain a correct form while walking or their upper body will move at a slower pace that their lower body.

Minute 20Once reached minute 20, the breathing patterns start to accelerate. There are two types of different muscles. Stabilizers that stabilize your body while walking and the movers. It is very important to observe closely the individual’s form and monitor the difference between once they start and once they go on minute number 20.

Minute 23Your breathing is really starting to increase now. Muscles require more oxygen, metabolic byproducts produced by the working muscles need to be removed via the lungs and so the rate and depth of your breathing increases.

Minute 25The body once reached the minute 25, it need to starts a gradual reduction of the intensity, Ideally you will always stay the aerobic range (55%-75%), it is also recommended to exercise in the 75%-80% for a small amount of time as long as the individual is able to control the breathing patterns. The more your body moves the more oxygen will be required.

Minute 30The heart rate starts to slow down, the intensity is lower, and the breathing patterns keep staying steady, inhaling less oxygen than when you are exhaling. Release of endorphins and serotonin produce a mental state of well being to the walker. That is why is recommended to walk little faster and stay in the aerobic frontier range.