Aerobic Training: Humans amazing ability to adapt

Aerobic/endurance training (or ‘cardio’) just like resistance training has an abundance of health benefits both cardiorespiratory and metabolic. One of my favorite parts of studying exercise physiology was knowing in depth how the body functions, it taught me how amazing humans really are, we are constantly adapting to an incredible array of environmental stresses. The more you are exposed to certain loads the more your body adapts to be able to withstand the new condition therefore increasing your ability to withstand more for a longer amount of time.

*This image attached shows how the bone adapts to increase load, in this case 12 weeks of jogging with occasional sprinting. You can see image of a long bone in the leg, the trabecular (inner parts if the bone) had greatly increased appearing fatter and less space between, the bone increased increased.

Cardiorespiratory Adaptations (meaning heart and lungs):

Just like any other muscle in the body the more you exert your heart the stronger it will get. With continuous aerobic exercise the left ventricle (chamber) of the heart becomes bigger and stronger increasing the amount of blood being ejected from the heart to deliver nutrient and oxygen to the body at a more efficient rate this consequently leads to a decrease in resting and sub-maximal heart rate plus the resting and exercise stroke volume. This is essential to heart health as blood pressure is defined as Cardiac Output (Cardiac Output * x Heart rate) x Total visceral resistance (resistance caused by arteries and veins etc.). Therefore, the more efficient your heart can operate the better your blood pressure. As you all may know high blood pressure is a primary indicator of cardiovascular diseases. To adapt to the increase in heat produced by aerobic exercise the body increases blood volume, red blood cell number and hemoglobin (Oxygen transporter) content resulting in a lower blood viscosity (reducing visceral resistance improving body’s ability to move blood around the body). Resulting in an increase in blood plasma, amount of water. Water has a high heat capacity which means it can absorb more heat without changing the temperature. Increases in body temperature changes the structure of amino acids (building blocks to our tissues) improving heat resistance maintains out tissue make up.

*Cardiac out = volume of blood pumped out during each heart beat

Metabolic Adaptations:

It was initially thought that increases in aerobic capacity was purely cardiorespiratory, while these changes definitely contribute, there are also metabolic aspects that are apparent in the primary muscles used during aerobic activity. Mitochondria enzyme gene expression increases due to the contractile rate in the specific muscles used causing there to be an increase in number and size of mitochondria, these cells are where the biochemical process of respiration and energy production occurs. An increase in capillary number also improves oxygen transfer within the muscle tissue. As your body adapts to aerobic activity it operates at a more efficient rate in response to the new stresses you are applying to it. It enhances the rate at which lactic acid (byproduct of the anaerobic glycolytic energy system) is removed and oxidized from your muscles while increasing your lactic threshold. This decreases the rate of fatigue and increases the amount of time your body can perform a task. Aerobic literally means ‘with oxygen’, in the Aerobic Oxidative energy system oxygen is required to ‘burn’ fats and glucose to synthesis ATP (primary energy source for cells). The higher glycogen (storage form of glucose) levels the longer you can perform activity; studies using muscle biopsies have shown that aerobic activity causes the body to adapt by depleting these levels at a slower rate. This decrease in the rate of glycogen use is compensated with increased fat oxidization during sub-maximal activity contributing to an improvement of endurance

*You don't have to do cardio it isn't essential to weight loss just like resistance training isn't essential but they WILL assist in reaching your weight loss goal. A healthy diet however is essential. If your goal is to be healthier (plus weight loss) then both a Cardio and resistance training program will be the most beneficial.

Reference: -J., Holloszy & E., Coyle (Unknown). Adaptions of Skeletal Muscles to Endurance Exercise and their Metabolic Consequences. Department of Medicine, Washington University. 56(4), 831-838 -B., Abernethy (2013. The Biophysical Foundations of Human Movement (3rd edition). Champaign IL, Human Kinetic

#Cardio #Running #Aerobic #MetabolicAdaptations #Cardiorespiratory