Porter's Health Hub

02/26/2013

Why Heart Rate Increases:

When doing some type of physical activity, whether it be a pick up basketball game or simply jogging on an olyptical, do you feel your heart begin to beat faster as you progress? Why does this happen? Many will explain that the heart beats faster to help pump blood to the muscles to deliver oxygen and nutrients required to maintain the exercise. While this is a correct assumption this explains why, but fails to achieve a physiological explanation of HOW heart rate increases and HOW it aids in assisting the muscles maintain their level of intensity.

It all begins with numerous receptors located throughout the body; the ones we will focus on in this discussion are the mechano-receptors, peripheral chemo-receptors and thermal receptors. Mechano-receptors identify when there is an increase in force/resistance against a muscle and when the length of the muscles either contract (shorten) or relax (elongate). The peripheral chemo-receptor's jobs are to determine when chemical levels in the blood are out of homeostasis. These receptors judge when carbon dioxide levels are to high, oxygen is running low or waste materials (lactic acid/hydrogen ions) are beginning to build-up. Lastly the thermal receptors simply judge the temperature of the body and any changes associated with it.

Now that we have defined the some of the key receptors, we can delve into the physiological explanation of why heart rate increases. When the body begins to perform an exercise, many elements naturally assimilate away from homeostasis. The muscles exert more force against some type of resistance which is sensed by the mechano-receptors. As the muscles progress through the exercise, carbon dioxide builds up, oxygen depletes and other waste materials begin to emerge. As the intensity of the exercise increases, these chemicals increase and deplete at a faster rate. Lastly the thermal receptors sense a change in body heat, which we begin to feel greatly when we begin to perspirate. Once these receptors have established that the body is needing refueling they send electrical signals to the cardiovascular control center. The CVCC as you would guess deals mainly with functioning of the heart, primarily via peripheral and sympathetic nervous systems. Once the CVCC identifies the signals from the receptors they relay the signals to these nervous systems. These systems then stimulates the heart at the SA and AV nodes to communicate with the heart that it needs to pump more blood at a faster rate to the working muscles. This will ultimately lead to an increase in heart rate and blood pressure.

Heart rate will then increase due to physical activity which causes an increase in blood pressure. Blood pressure increases so that the heart contracts at a faster rate to get blood to the lungs and body more quickly and efficiently. The blood carries oxygen and nutrients to the muscles which is vastly important, especially during an exercise activity. The oxygen is primarily used in the glycolysis/krebs cycle (also referred to as aerobic respiration) to
create ATP. Adenosine Tri-Phosphate are tiny energy molecules that power our muscles and give us the ability to perform the task at hand. Lastly as the blood is carried back to the heart, it takes with it the carbon dioxide and waste materials created from aerobic respiration. These chemicals are then purged and expelled from our body.

-Overview-

1. Receptors sense a disruption in homeostasis due to force against muscles (from some type of physical act).
2. Relay to the cardiovascular control center.
3. CVCC relays to PNS and SNS.
4. These nervous systems stimulate the AV/SA nodes of the heart.
5. Heart rate increases to cause an increase in blood pressure.
6. Blood pressure causes heart to contract at faster rate getting blood out into the body more efficiently.
7. The blood supplies oxygen and nutrients to the muscle.
8. Body uses the oxygen in aerobic respiration to create ATP.
9. ATP power the muscle enabling it to perform task.
10. On return to the heart carbon dioxide and waste materials taken back.
11. Waste materials expelled from body.

02/22/2013

Interesting fact:

Ever had a baby grasp tightly onto your finger and thought to yourself, "Awe he likes me."? This may be a cute and common association to that theory; however, that tight grasp is due to a primitive reflex. A primitive reflex is a survival instinct/protection instinct associated with babies. Some other examples are: sucking, grasping the Moro and Babinski reflexes.

02/21/2013

Motor Movement Behavior- Part 1

Motor behavior is a sub-discipline of the exercise science study culminating with three areas of focus: motor movement, motor control and motor learning. Studying motor behavior is achieved by learning how different variables, such as obstacles, tasks and even motivation, can alter motor movement. The three sub-disciplines associated with motor behavior give a descriptive outlook on how the body adapts throughout life by learning new movements/skills and advancements in "fine-tuning"gross motor movements.

Motor Development is the first sub-discipline detailing motor behavior. Simply put, motor development is the maturation of motor abilities within the body. This development is a continuous process that is sequential over a life time. For example, a baby learns to crawl before walking, just as a young child needs motor development for walking properly before beginning to run. Development of motor abilities is age related, but not necessarily age-dependent, meaning that some individuals have a faster growth and maturation process than others. This can lead to advancements in early age groups that can be easily seen in youth sports; where some individuals are at a more developed stage giving the edge over those individuals maturing at a slower rate. These early "rough" motor movements constantly adapt to change over time and eventually become more fine tuned movements. Example being a baby utilizing hip in their gait and this eventually adapts to bending at the knee to better aid in a normal walking motion.

While development is key in human nature, control of these motor movements is another important aspect of motor behavior. Motor control, the second sub-discipline, is defined as neurological, behavior and physical processes that aid in human movement. Mainly deriving from a neurological standpoint, this portion of motor behavior works inside the body before, during and after the motor movement has been completed. For example the vast, complex network inside the human body, the Central Nervous System (CNS), plays a major role in motor control by sensing the enviroment and task at hand. The CNS then aids the body in correctly navigating a correct motion to complete the task by consistently relaying messages to the brain where it is interpreted. These messages are then sent back out into the body where it is relayed to the corresponding muscle to perform the motion.

The last sub-discipline of motor behavior is the simplest to grasp, yet the hardest physically to achieve. Motor learning is a permanent acquisition of a motor movement skill acquired through constant practice, repetitive motion and task association. For example, a beginning youth basketball player may have a difficult time consistently making free throw shots. A professional shooting guard or point guard in the NBA; however, can consistently make free throw shots with ease due to the amount of practice and repetitive motion experience gained over time. Simply put, motor learning is commonly referred associated with "muscle memory" which incorporates the same factors: repetitive motion, task association and practice.

These sub-disciplines of motor behavior give a stellar insight on how truly amazing the body is and how it can adapt to change, learn new skills and fine tune skills learned in the past. Motor behavior; however, can be altered negatively and positively through different types of constraints. These constraints will be discussed in part 2 of this motor behavior unit!

Thanks for reading,
Josh

02/20/2013

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08/15/2012

Stretching: This first article will be a quick sum of how a good stretching routine can aid greatly in enhancing overall body strength and flexibility.

Stretching is one of the most fundamental, yet overlooked factors in athletics. Jumping right into an exercise routine or workout seems to put stretching and warming up on the back-burner. Many see stretching as an optional routine that seems to stall or "bog down" the rest of the workout. Stretching; however, should be considered the most important aspect of a workout routine. Ever feel a "grinding sensation" while doing a simple lift such as pushups? Maybe a slight cramping in the quadriceps while performing a back squat? Many of these nagging pains can be alleviated with a simple addition or change to a workout program. Yes, stretching can be the vital key to solving this issue. Stretching has many benefits that correlate well with workout routines. These benefits range from short term advantages like pain relief, to long term advantages such as increased flexibility and improved athletic performance. Stretching increases the range of motion (ROM) of muscles and their movements. Essentially with an increase in ROM greater flexibility can be achieved. This in turn can increase athletic performance over time, while decreasing the risk of injury. The increase in ROM and flexibility can advance the physical aspect of the body and aid in movements that could normally injure the targeted body part. Take for instance the recent increase in hamstring injuries within the NFL. Many of these hamstring injuries occur during a "planting phase" in which the foot plants into the ground, leg fully extended, at an angle of stress not normally utilized by the body. This added stress can cause tightened hamstring muscles to extend past its normal boundary causing a strain. Not to take away from the conditioning level of a professional athlete, this occurrence of hamstring injuries this year could be taken into account due to a lack of warm-up and stretching. While other factors can be present in these types of injuries, stretching can increase the ROM of that particular muscle greatly diminishing the risk of an over-stressed muscle.While stretching increases muscle elasticity it also aids in increased blood transfer to muscle tissue. The extra blood to the muscles gives the body an energized sensation and allows for longer workout periods. Stretching brings about many positive aspects to a workout and should be implemented into any routine both as a warm-up and cool-down.