Unit 1 - Anatomy and physiology for health and exercise - Energy systems Flashcards
What is ATP in simple terms?
For your muscles—in fact, for every cell in your body—the source of energy that keeps everything going is called ATP. Adenosine triphosphate (ATP) is the biochemical way to store and use energy. … When the cell has excess energy, it stores this energy by forming ATP from ADP and phosphate. It provides the energy to drive the sliding filaments in muscular contractions.
Where to we source ATP from?
From the macronutrients in the food we eat: carbohydrates (CHO), fats and protein. Although all important, fat and CHO are the preferred energy sources.
What are the 3 distinct energy systems?
the creatine phosphate system the lactate system the aerobic system
Describe the structure of ATP.
ATP is an energy-rich compound, composed of one adenosine molecule, bound with three phosphate molecules. Energy is stored in the bonds that link the phosphate groups to the larger adenosine molecule, and are called high energy bonds
When does ATP release its energy?
when one of its two high energy bonds is broken (by the enzyme ATPase), and 7.3kcals of energy are released per mol of ATP. After this breaking down reaction, an adenosine molecule bound with two phosphate molecules (adenosine diphosphate, or ADP) and an unattached phosphate group is left.
This occurs during muscular contraction and is controlled by the enzyme myosin ATPase.
is the ATP store in muscles very large?
No, it is very limited, so muscles must be continually replenished if exercise is to continue.
The energy systems serve this purpose by providing the energy to convert ADP back in to ATP, for use by the cells. These three systems are the creatine phosphate system, the lactate system and the aerobic system.
For high intensity, low duration activities, such as sprinting, long jumping, or shot putting, energy for muscular contraction is required quickly. This is primarily supplied by what?
intramuscular stores of ATP and creatine phosphate (CP).
How long may intramuscular ATP stores last in exercise?
Only a few seconds.
Once intramuscular ATP stores have been depleted, how can they be regenerated?
they can be almost immediately regenerated by the breakdown of creatine phosphate. This compound, like ATP, has a high energy bond, which when broken down, will release enough energy to yield an ATP molecule.
How long do CP stores last?
CP stores are also limited, thus exercise will only last for a very short period of time, approximately 5 – 8 seconds. In fact, it is noted that during a 100m sprint, lasting approximately 10 seconds, runners are usually slowing down in the final few seconds; the winner being the one who slows down the least.
Does the Creatine Phosphate system require oxygen?
As this system is derived exclusively from chemical energy stored within the muscles, the process requires no oxygen (anaerobic) and places no immediate demands on fat or carbohydrate stores.
How long is the recovery period in Creatine Phosphate systems?
Depending on the intensity and duration of activity, the recovery period for this system ranges from 30 seconds to 4 minutes.
Define the Lactate system.
- the lactate system is generally associated with the burning sensations felt during high-intensity activities.
- The lactate system can essentially bridge the gap between the aerobic and CP systems
- It allows rapid ATP production to continue beyond the few seconds of the CP system, and at a rate significantly greater than the aerobic system can achieve
- It can sustain exercise activity for between 60 – 180 seconds e.g. 400m on the track or 100m in the pool
Describe the process of how the lactate system provides a fast supply of energy.
- by the incomplete breakdown of the carbohydrate glucose, taken from the blood, or made from the breakdown of glycogen (stored glucose).
- Glucose is converted in a number of stages to a substrate called pyruvate.
- The pyruvate will then enter one of two directions, purely dependent on whether oxygen is present or not.
- If there is sufficient oxygen, the pyruvate will enter the aerobic energy system.
- If there is insufficient oxygen to meet energy demands, it is converted, very rapidly, to lactate.
- This process will yield 3 ATP per glucose molecule, and does not occur in the presence of oxygen.
What is the cause of the burning sensation and fatigue during high-intensity activities?
The cause is a concurrent build-up of hydrogen ions, which causes pH levels to drop, a state known as acidosis. This state of acidosis inactivates various enzymes involved in energy production and can interfere with the muscles contractile ability.
does lactate production cause an increase in hydrogen ions, or does it just occur at the same time?
the production of lactate is a result of the body’s attempt to prevent acidosis and is not actually the cause of it.
What happens with the lactate levels during low to moderate activity - and how does it change when an activity becomes too great for the aerobic system?
During low to moderate activity, energy requirements are easily met using the aerobic system, thus lactate levels remain relatively unchanged.
When the energy demands of activity become too great for the aerobic system to manage and hydrogen ion levels increase, the lactate system will start to be utilised and blood lactate levels will start to rise.
When lactate acid system reaches levels sufficient to bring about the familiar decline in performance and burning sensations associated with this type of intensity, how long is the recovery time?
Recovery from this type of activity can vary from 20 minutes to two hours depending on intensity and duration.
Define the aerobic system.
Aerobic simply means ‘with oxygen’, and refers to the energy system that produces ATP from the complete breakdown of carbohydrate and fat, in the presence of oxygen.
The aerobic energy system is dominant during lower-intensity activities when ATP demands are low and oxygen consequently is relatively plentiful.
The aerobic system produces carbon dioxide, water and heat as by-products of the breakdown of CHO and fat.
What are the limits on the rate of aerobic ATP production?
when exercise intensity reaches a certain point, the lactate system will start to provide more and more energy during the buffering process.
The point at which this occurs will vary according to individual aerobic fitness, the higher the aerobic fitness the higher the exercise intensity that can be maintained without fatiguing waste products accumulating (i.e. one can run faster for longer).
Assuming the absence of any overuse injury, the recovery time from this type of exercise will be the time taken to eat, drink and replenish fuel stores.
What are the macronutrients that supply the body with ATP during aerobic metabolism?
fat (fatty acids) and carbohydrate (glucose)
What is the saying about when does fat burn?
Fat is commonly said to ‘burn in a carbohydrate flame’, meaning that fat cannot be broken down without carbohydrate present.
At rest or during low-intensity activity most aerobic energy is supplied by what?
Fat.
As exercise demands increase and ATP is required more quickly, what nutrients contribute to the aerobic energy system?
carbohydrates will begin to contribute more to the process.
Although protein contains as many calories of energy as glucose, it will contribute little to energy production so long as sufficient carbohydrates are available.
What is the main limit on aerobic energy production?
The ability to take in, transport and utilise oxygen (these will be referred to as pulmonary, cardiovascular and muscular changes respectively)
Aerobic training has been shown to enhance which three areas?
- pulmonary changes
- cardiovascular changes
- muscular changes
Describe the Aerobic training adaptations of pulmonary changes?
The principle adaptations are improvements in the efficiency of the respiratory muscles.
This is indicated by an increase in maximal breathing rate and tidal volume (i.e. one can breathe quicker and deeper at maximal intensities). It is also suggested that more efficient respiratory muscles are likely to use less oxygen, produce fewer waste products and thus potentially increase oxygen availability to other working muscles.
Describe the Aerobic training adaptations of cardiovascular changes?
- the heart of a trained individual shows significant hypertrophy and improvements in coronary blood flow
- increased stroke volume, indicated by a lower resting heart rate, and greater cardiac output at maximal heart rate
- increase in blood plasma volume which may also contribute to the increased stroke volume, and oxygen transport
- changes in the control of blood distribution, increased arterial diameter and capillary density also serve to maximise blood flow to the muscles
Describe the Aerobic training adaptations of muscular changes?
- improved blood supply to the active muscles is matched by a greater ability of these muscles to extract and utilise oxygen from the blood
- increased size and number of mitochondria (structures within the muscle cells, where aerobic ATP production takes place)
- increases the muscles ability to metabolise (breakdown) fat and carbohydrate
- maximise the aerobic potential of muscle fibres
Describe the training adaptations in the lactate system.
- improvements in the cardiorespiratory system
- regular anaerobic training improves tolerance to the build-up of fatiguing waste products
Describe the training adaptations in the CP training system.
- increased muscle size
- a predomination of fast-twitch muscle fibres
- can significantly increase muscular stores of anaerobic fuel sources i.e. ATP, creatine phosphate and glycogen
- improved activation of the muscle by the nervous system
Do the energy systems overlap?
Yes, there is considerable overlap between them.
At any one time, all three systems could be providing the body with energy.
The relative contribution of each is determined by the intensity of the activity.
During a jog or run, when the intensity is low, ATP requirements are met by the aerobic system. At higher intensities, for example, when going up a long hill, there is a greater contribution from the lactate system. At some point, waste products would accumulate to a level where further increases in intensity become difficult.
Also, as one energy system becomes exhausted the others can take over
Describe a method for Lactate testing.
Lactate testing samples blood from a lancet, used on the finger, earlobe, or another part of the body. Lactate testing is considered lab testing, even if it’s practical and portable for field tests, simply because it is invasive.
Many lactate tests take place in conjunction with gas exchange testing, meaning traditional VO2 assessments are performed with blood testing.
With heart rate monitoring, what is the measurement of the aerobic training zone?
Between 60 - 90% of one’s maximum heart rate (220 – age) or 50 – 85% of one’s VO2max.
What is RPE (also known as the Borg scale, after its creator - Gunnar Borg, 1998)?
a subjective rating of how hard the exerciser feels they are working.
Typically two scales have been used; either the 6 – 20 scale (6 = no exertion at all, 20 = maximal exertion) or a simplified 1 – 10 scale
What is the talk test?
it identifies the exercise intensity at which ‘normal’ speech can no longer be sustained, which is indicative of the increased breathing rate triggered by exercise activity.
The breathing rate is dictated by the volume of circulating gases in the blood which, in turn, is directly determined by the level of work being undertaken by the muscles.
What are Metabolic equivalents (METs) ?
A method of monitoring exercise intensity.
These are based on multiples of an individual’s resting oxygen consumption.
At rest, the average individual will consume approximately 3.5 ml of oxygen per kg of their body mass. This is the equivalent of 1.0 MET, thus energy expenditure at rest is 1.0 MET.
Walking, for example, will consume approximately three times the oxygen as resting metabolism, therefore, is the equivalent of 3.0 METs.
Running flat out for a couple of minutes, on the other hand, could be rated as high as 30.0 METs.
