Exercise Physiology 101 & Primer


The topic of best exercise strategy and approach for improved health and appearance can be an involved one. The results and progress a person makes is incumbent on goals and current state of physical fitness and capabilities. With the abundance of sometimes conflicting research data and to the degree that people get their desired results can be confusing. It's almost like alchemy to understand general human, nutrition and exercise physiology. As an individual you can rely on general information or you can dig a bit deeper to help make smart choices. The objective of this article is to give you information and data to help you raise your awareness level and focus on the correct strategy and habits to reach your fitness and health goals. That is to say it your goals are to improve appearance, functionality, heart health and to age more gracefully.

Your metabolism is a complex arena of biomedical chemical processes. Though medical and fitness professionals attempt to make it easy to comprehend, there are multiple arrays and dimensions to consider. That is to say that there are many "moving parts" to the entire puzzle. To clearly demonstrate the details of all of the moving parts without putting you to sleep would be tricky and beyond the scope of this article. However, I am going to attempt to give you a better understanding of the big picture and all of the moving parts. Without having some basic understanding of human physiology, you may be at risk of spinning your wheels and losing precious time in acheiving your goals. I know that many people "don't know" or "don't care" about the details and they simply want to "burn" and do things that "work". This is understandable, but the fact of the matter is that like most aspects of life, "the devil is in the details". The more information you have and more importantly the more information you absorb, the better.

About Metabolism

Let's start by addressing the issue of metabolism. "Metabolism" is a word that many people use and refer to, but is seldomly explained appropriately. An indication to me that many are un-informed about how metabolism works is the common statement: "I dont know what happened, it think my metabolism must have slowed down!" Unless your M.D has has informed or diagnosed you with a hormone or thyroid disfunction, YOU are in control of your own metabolic destiny. Metabolism refers to the countless chemical processes going on continuously inside the body that allow life and normal functioning. These processes require energy from food. The amount of kilojoules (kJ) your body burns at any given time is regulated by your metabolism.

Two processes of metabolism
Hormones (chemical ‘messages’ secreted by the glands of the endocrine system) and the nervous system control your body’s metabolism. Your metabolism can be upset by a variety of events, including genetic disorders and hormonal problems.

There are two complementary parts to your metabolism, which are carefully monitored to make sure they remain in balance. They are:

  • Catabolism - Refers to the breakdown of food components (such as carbohydrates, proteins and fats) into their simpler forms, which can then be used to create energy. Think of it as your "destructive metabolism" which produces the energy required for all activity in the cells. In this process, cells break down carbohydrates and fats to release energy and fuel all anabolic reactions, such as heating the body, giving the muscles power to contract and the body to move. As complex chemical units are broken down into more simple substances, the waste products released in the process of catabolism are removed from the body through the skin, kidneys, lungs, and intestines.

  • Anabolism - is your "constructive metabolism" that gives which is all about building and storing. All anabolic processes support the growth of new cells, the maintenance of body tissues, and the storage of energy for use in the future.

Metabolic rate (or total energy expenditure)
Your body’s metabolic rate (or total energy expenditure) can be divided into three components:

  • Basal metabolic rate (BMR) - is the amount of kilojoules burned at rest and contributes 50-80 per cent of your energy used.

  • Energy used during physical activity - this is the amount of kilojoules burned during movement and physical activity; in a normally active person, this component contributes 20 per cent of daily energy use.

  • Thermic effect of food - this is the energy you use to eat, digest and metabolise food. It contributes about 5-10 per cent of your energy use.

Everyone’s Metabolic rate is different
It's imporant to note that everyone’s metabolic rate is different and is incumbent of a number of factors working together inclusive of:

  • Body size - larger adult bodies have more metabolising tissue and a larger BMR.

  • Age - metabolism slows with age, due to a loss in muscle tissue but also due to hormonal and neurological changes.

  • Growth - infants and children have higher energy demand per unit of body weight due to the energy demands of growth and the energy needed to maintain their body temperature.

  • Gender - generally, men have faster metabolisms than women because they tend to be larger and have less body fat.

  • Genetic predisposition - your metabolic rate may be partly decided by your genes.

  • Amount of lean muscle tissue - muscle burns kilojoules voraciously.

  • Amount of body fat - fat cells are sluggish and burn far fewer kilojoules than most other tissues and organs of the body.

  • Hormonal and nervous controls - BMR is controlled by the nervous and hormonal systems; hormonal imbalances can influence how quickly or slowly the body burns kilojoules.

  • Dietary deficiencies - for example, a diet low in iodine reduces thyroid function, which slows the metabolism.

  • Environmental temperature - if temperature is very low or very high, the body has to work harder to maintain its normal body temperature; this increases the BMR.

  • Infection or illness - BMR increases because the body has to work harder to build new tissues and to create an immune response.

  • Crash dieting, starving or fasting - eating too few kilojoules encourages the body to slow the metabolism to conserve energy; BMR can drop by up to 15 per cent. There is also loss of lean muscle tissue, which further contributes to the drop in BMR.

  • Amount of physical activity - hard-working muscles need plenty of energy to burn. Regular exercise increases muscle mass and ‘teaches’ the body to burn kilojoules at a faster rate, even when at rest.

  • Drugs - some drugs, like caffeine or nicotine, can increase the BMR.

Common Reasons for "Exercise"

Reasons for exercise can very depending on your goals. Some people naturally encompass exercise in their daily ways of life. For example, a college basketball player exercise during their competitive bouts as well as in training and preparing to compete within their sport. An adult that has a desk job and family to raise will probably not have exercise encompassed within their ordinary lifestyle, but they will want and need to exercise if they have an interest in avoiding and slowing deterioration and illness that can naturally occur as the sands of time continue to tick.

  • To Improve and Maintain Health. Exercise is the primary and best tool for improving and maintaining health vital statistics such as resting heart rate, blood pressure, chronic blood glucose levels and levels of bad cholesterol. Exercise is the essential element in preventing and reversing type-2 diabetes, preventing stroke, preventing heart attack/disease, preventing/slowing the alheizmers affect ,preventing osteoporosis and preventing some forms of cancer. In other words, exercise is an essential aspect for preventing and slowing general "onset" deterioration and aging.

  • To Improve and Maintain Appearace. Many people decide to embark on an exercise program due to the fact that they would like to "lose weight" or "look better" in shorts or a swimsuit for a vacation, wedding and other events. Exercise can be used to improve appearance as the onset years settle in and you have gained more than desired weight of fat around the midsection. Appropriate exercise can be used to reverse the process of gaining weight fat and losing weight of muscle as the result of years of putting exercise and fitness on the backburner.

  • To Improve/Maintain Performance and Prepare for Athletic Events and Career Related Duties. Exercise is key for people that make a living in which there physical performance is required. For example, law enforcement, soldiers and firefighters have minimal physical fitness requirements. Athletes of all levels have exercise encompassed in their lives to stay competitive and functional. Some people may use exercise to prepare for a marathon.

Anaerobic and Aerobic Exercise & Their Energy Sources

There are a number of aspects for consideration in exercise and training prescriptions. Since the early days of the olympics, strength, fitness and athletic trainers have used many methods and permutations of exercise for athletic performance and strength. If we were to rewind the clock to the prehistoric cave man days, exercise was encompassed within our lifestyles. For example, we probably had to stalk, plan and run down water buffalo for dinner. Nowadays, we go to restaurants and over eat. In many ways, our exercise prescriptions for general health are attempting to emulate the lives that we used to live when times were simpler. Though technology and farming has changed over the years human physiology has not. On the other hand, from technology we have learned that rapid, quick aging and onset diseases can be prevented and slowed down via exercise.

Some terms and types of fitness training you may hear about can be inclusive of: Endurance training, Resistance Training, Cardio Training, Flexibilty Training, Functionality Training.. Some of these terms are loosly used and defined. In some ways, some of these definitions are interchangeable. However, regardless to the type of training or exercise that one participants in, the exercise falls into one or both types of exercise; "Anaerobic" or "Areobic". I have noticed that with definitions coming from all over the place that there is some confusion in regard to what these terms actually mean and are inclusive of. Something else that is seriously overlooked by most is the physiology of the types of exercise, the overall picture and how there are different reasons for and are different fuel sources for the 2 types of exercise. A common denominator question and issue in regard to general health and aesthetic improvements for most people is the topic of exercise to burn/reduce fat and build/keep muscle. It turns out that there is a bit of a "ying and yang" to this topic as it pertains to exercise.

ATP the ENERGY Molecule

Adenosine triphosphate (ATP) is the source of energy for all muscle contractions. Without ATP present in your bloodstream, you cannot produce physcial energy and have muscle contractions. Though I dont want to bore any one or get too nerdy of too technical but energy is release when the ATP molecule is broken down into ADP+P(adenosine diphosphate and phosphate group). There is a complex biochemical process that occurs to split the ATP molecule into ADP+P to release energy. Maintaining the availability of ATP for muscle contraction is a limiting factor, ATP is not stored in large amounts in skeletal muscle. When ATP is needed, you must produce this. You must oxidate and convert from somewhere in your body to produce ATP. Viable sources of ATP come from both anaerobic (does not require O2) and aerobic (requires O2) means. The primary energy source for a given activity will primarily depend on the intensity of muscle contractions.

Aerobic Exercise

By defintion, aerobic exercise is a mode of exercise that uses oxygen as the primary catalyst in creating energy/ADP the energy molecule which is essential in generating, producing, initiating and substaining muscle contractions. These muscle contractions are generally medium to low-intensity and can occur for long durations. Again, this form of exercise is low-medium intensity and does not maximize muscle contractions and energy. Upon increasing energy exercertion, you will switch to the other mode of exercise Anaerobic. Another way to think of aerobic exercise is that you dont not rapidly fatigue. The rate at which you are using/exerting energy/ADP is MANAGABLE from oxidating phosperation.

Samples of Aerobic Exercise:

  • Long distance Running/Jogging
  • Long distance low-medium instensity cycling
  • Walking
  • Aerobic Classes that can include Dancing

Aerobic Energy Pathway

In aerobic Metabolism, complex biochemical processes occur in which we are able to "oxidize" and create enough of the energy molecule ADP to sustain muscle contractions. Aerobic energy production uses oxygen as the catalyst and begins the process of extracting glucose/glycogen out of our fat cells and into our blood stream for further metabolism to create ATP. It is important to note that aerobic metabolims/energy production initiates from fat. There is a difference from burning calories .vs burning fat. When muscle contractions our low in intensity, our bodies can successfully "oxidize" energy from fat cells with adequate ATP supply to get the work done. For example, in our day in day out low muscle contraction activities, we burn mostly calories/energy from fat reserves. As muscle contraction and output intensity increases beyond 50% of maximum heartrate, we are no longer cabable of supplying enough ATP to get the work done and there is a different energy pathway initiated. It is important to note that the energy pathway for aerobic energy production is abundant. ATP is not readily and abundant in storage within our bloodstream. When working at "low intensity" we are able to use oxygen to initiate the "glcycosis" to supply enough ATP to get the work done. This is why aerobic exercise is LONG in duration and output capability.

Pros, Cons and Caveots of "Aerobic" exercise

  • Pros An advantage of aerobic exercise is that the energy burned/used is primarily derived from oxidation and glycosis of body fat.

  • Cons This energy source and exercise style is for the "light" work. If you were an athelete, attempting to build muscle or flat out running from a bear in the woods, your "aerobic" capacity would not be much help. In attempting to sprint and climb a tree in attempt to get away, your are in pure "anaerobic" mode. In addition, anearobic fitness increases power, strength, a muscle strength. Your heart is a muscle.

  • Caveots Though there is some confusion, everyone has a "aneoribic" threshold regardless to your current state of physical fitness. To increase your state of physical fitness and capacity we ALL must execute and work on our aneorib condition. There are some complications as well. For example, in your workout we all need to build/maintain muscle for metabolism increases. This means that long bouts of aerobic exercise for fat burning would be optimal after anearobic training due to the fact that the after this the anaerobic pathway has been deplated and you will primary run/work on areobic or body fat glycosis.

Anaerobic Exercise

Anaerobic Exercise/Movement is the permutation and form of movement in which a GREAT deal of force is expended rapidly. In this scenario, the muscular contractions and force used and generated is needed in such abundance that the areobic energy pathway can not sustain this type of activity. In this type of movement, oxygen is NOT the catatyst that initiates the oxidation and glycosis to produce the ATP needed to get the work done. Anaerobic activity can be in the form of burst of speed and/or burst of serious muscle contraction and output. This is the "heavy lifting" mode of exercise so to speak. Some studies indicate that the maximum amount of time someone can execute an aneorobic "burst" is between 10 seconds and 2 minutes. The reason for this is a result of the complicated biochemical process that is used to create your ATP. In simple terms, the rapid use of ATP or, ADP/Creatine leaves an exhaust so to speak in the bloodstream after expended. Lactacte is a salt base and the presence of this within your bloodstream will shutdown and limit the amount of work expended untill you replinish. You can easily do your own experiment to find your aneorobic threshold. For example, how long can you sprint at full speed before you are forced to stop? How many squats and with how much weight can you execute before your "out of gas?"

Samples of Aerobic Exercise:

  • Sprinting
  • Jumping
  • High Intensity Interval Training
  • Resistance Training
  • Running, Jumping, Manuevering and Climbing from a Wild Animal in the Woods!

Anaerobic Energy Pathway

The metabolism and energy pathway used in "anaerobic" activity is an even more complicated biochemical process than in areobic exercise. The catalyst or starter needed for musclar contractions is the energy molecule ATP which is NOT stored in abundance within our muscle cells and we must acutely produce and store it into our muscle cells to execute musclar movements/contractions. There are two sytems and modes at work to get the ATP to our cells for anaerobic work and exercise. By default, we have about 2-4 seconds worth of ATP stored within our muscle cells. So, in the scenario of voluntarily executing an anaerobic activity we will 1st go thru the 2-4 seconds worth of ATP in our muscle cells. Then, in the continuation of anaerobic "energy production" our bodies will use acutely use available creatine phosphate(cp) to resynthesize ATP until the CP runs out which is about another 6-10 seconds. This inital anaerobic energy pathway has different "gears" do to this so create, supply and use ATP. This system is called the ATP-CP Anaerobic Energy Pathway system and again, it supplies the ATP/Energy for the initial voluntary high intensity muscle contractions.

Once you have used all of your energy/ATP molecules from the ATP-CP Anaerobic Energy pathway, you will switch to and primary use the next stage of Anaerobic metabolism and energy/ATP production which is Anaerobic Glycolysis to continue to create ATP/Energy to continue with Anearobic exercise. The anaerobic energy pathway, or glycolysis, creates ATP exclusively from carbohydrates/glycogen stored within muscle cells, with lactic acid being a by-product. Anaerobic glycolysis provides energy by the (partial) breakdown of glucose without the need for oxygen. Anaerobic metabolism produces energy for short, high-intensity bursts of activity lasting no more than several minutes before the lactic acid build-up reaches a threshold known as the lactate threshold and muscle pain, burning and fatigue make it difficult to maintain such intensity.

Advantages of Anaerobic Exercise

  • There are many forms of Anaerobic exercise for everyone and all backgrounds. Regardless to your current state of physical fitness, EVERYONE has an anaerobic/lactate threshold if your 25 or 55. This is where you essentially run out of quick energy and have to replenish your ATP stores. This means that if perhaps you have a knee injury and cannot sprint that you can execute some mode of weightlifting/resistnce training. Or, if cannot execute jump ropes to exhaustion, that you can perhaps throw a medicine ball to exhaustion.

  • Superior mode of exercise to improve and maintain Heart Health. In anaerobic exercise, your heart rate must go and down with great burst of energy. Studies have proven that resistance training increases the hypertrophy of the left ventricle of the heart. Anaerobic exercise is the key mode of exercise to bring down high blood pressure and flush out the bad cholesterols.

  • Can increase Metabolic rate! The only variable aspect that you have of increasing your metabolic rate is to increase your percentage of lean body muscle! Each gram/cell of muscle tissues burns and needs more calories of energy for maintainance than fat tissue. In addition, you burn calories as you are procuring and catabolising your muscle cells. In other words, you have to burn more fat to replinish your muscle cells after anaerobic style workouts.

  • The primary method of re-shaping your physique. In areobic exercise you are not building muscle. In addition, your not burning that much fat without long, long periods of exercise. If a person where to ONLY execute aerobic exercise and they are shaped like a pear, the result would be that they may look like a smaller pear at best. To change your shape and physique a person will need to procure muscle which adds shape and tone.

Conclusion - What does all of This Mean?

As with many things in life, when we increase our knowledge and awareness, we are able to make better choices and increase focus. The topic of health, fitness and nutrition DOES have many variable moving parts. These complex variable moving parts can cause the general population much confusion. For example, a 50 something type 2 diabetic with bad knees will not get much in terms of health improvements by walking the marina and eating more oatmeal. The devil is in the details. A person in this scenario would get better results if they began to QUANTIFY their carbs, proteins and fats in accordance with their acute blood glucose levels. In addition, this person could use the "marina walk" time more efficiently with anaerobic exercise that is within THEIR specific thresholds. In addition, this person would do better to put more focus on hypertrophing their muscles(heart included) as opposed to allowing their muscle to atrophy/deteriorate.

It's important for individuals to consider their current state of fitness and circumstances to determine the best exercise routines to execute. Things are not always as they seem. Many people use the term "lose Weight" and they have a focus on this generic term. However, the objective should be to get healthier and get rid of fat for good! A person that is in their 20's without too much fat body and without the sands of time increasing their risk of disease, can perhaps have a casual attitude in regard to their exercise efforts. On the other hand, someone that is in their 50's with a higher risk of disease WILL need to take a more educated, serious and efficent approach in their exercise efforts to improve and slow down deterioration.

The human body is a really amazing organism and can withstand years of abuse. The human body is so great that a person can reverse and change direction with the correct efforts. Again, the physiology of humans is pretty complex but really amazing. However, the best way to lose/reduce weight of fat is to avoid gaining too much in the first place. The best way to slow down the aging process is to avoid going through years of chonic non-compliance.