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Work The complexity of task demanding energy!! 3
Quick and powerful Graceful & coordinated Sustained for many hours And is dependent upon the capacity to produce energy Quick movements-lasts a few seconds Reduced speed-lasts for several minutes Reduced intensity(50%)-lasts for several hours The body uses different energy systems for each activity 4
Energy in the human body come from the breakdown of nutrients like carbohydrates, proteins and fats Food = Energy (ATP) The end result of this breakdown is the production energy in the form of Adenosine triphosphate (ATP) 5
Carbohydrates Fats Proteins Digestion Glucose Fatty acids Amino Acids Absorbed into the blood & transported to cells (muscle, liver & nerve) They are used to produce ATP or stored 6
The two major ways the body converts nutrients to energy are: Aerobic metabolism (with oxygen) Anaerobic metabolism (without oxygen) There are 3 Energy systems that interplay to supply the fuel needed for work and exercise, with the intensity and duration of the work determining which method gets used when 7
The 3 energy systems are: 1) ATP-PC System (Anaerobic without oxygen) 2) Anaerobic Glycolysis (Anaerobic without oxygen) 3) Aerobic (Aerobic with oxygen) ATP is stored in small amounts, therefore the rest is stored as: Glucose = Glycogen (muscle & liver) Fatty Acids = Body fat Amino Acids = Growth, repair or excreted as waste 8
ATP (Adenosine Triphosphate) ATP is the usable form of energy in the body. The energy from foods that we eat, such as carbohydrates, has to be converted into ATP before the potential energy in them can be used. An ATP molecule consists of adenosine and 3 Phosphates Adenosine P P P ATP breakdown Energy is released from ATP by breaking down the bonds that hold this compound together. Enzymes are used to break down ATP. ATP-aseis the enzyme used to break down ATP into ADP (adenosine diphosphate) and a single phosphate. Adenosine ENERGY P P P 9
For contractions to continue ATP must be REBUILT This comes from the splitting of CP (Creatine Phosphate a Hi energy source, automatic) When ATP is used it is rebuilt as long as there is CP Energy released from CP breaking down, resynthesizes the ADP & P The ATP-CP energy pathway (sometimes called the phosphate system) uses ATP CP stores directly. This pathway doesn't require any oxygen to create ATP. Supplies about 10 seconds worth of energy and is used for short bursts of work such as a lift and carry for a sort distance. It first uses up any ATP stored in the muscle (about 2-3 seconds worth) and then it uses creatine phosphate (CP) to resynthesize ATP until the CP runs out (another 6-8 seconds). After the ATP and CP are used the body will move on to either aerobic or anaerobic metabolism (glycolysis) to continue to create ATP to fuel work or exercise. 10
a. Creatine Phosphate (CP) Creatine High energy bond P b. CP = Creatine + energy for resynthesis of ATP + P Creatine P Energy c. ADP + energy from CP + P = ATP (reversal of ATP = ADP + P + energy for work) Adenosine P P P 11
The anaerobic energy pathway, or glycolysis, creates ATP exclusively from carbohydrates Creates this ATP without the need of oxygen Lactic acid and Hydrogen ions are by-product of this system. Anaerobic glycolysis produces energy for short, highintensity 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. 12
Without oxygen = Activities that require a large burst of energy over a short period of time Anaerobic Glycolysis = Production of ATP from Carbohydrates without oxygen (breakdown of glucose) Since glycogen is stored in the muscle & liver, it is available quickly This system provides ATP when ATP-CP runs out ATP-CP lasts for a few seconds, the Anaerobic Energy System allows for 2-3 minutes of work 1. The process to produce ATP is not as fast as ATP-CP, which makes muscle contraction slower 2. When oxygen is not present the end product of glycolisis is lactic acid, which causes the muscles to fatigue 3. Anaerobic Glycolisis is less efficient in producing ATP than Aerobic Glycolisis, BUT is needed for a large burst of energy lasting a few minutes 13
Aerobic system fuels most of the energy needed for long duration activity. It uses oxygen to convert nutrients to ATP. This system is a bit slower than the anaerobic. Relies on the circulatory system to transport oxygen to the working muscles before it creates ATP. When is it used? Endurance events, less intense activities, that last long periods of time. This system creates 38 molecules of ATP from 1 molecule of glucose 14
Glycogen Glucose Energy ATP ADP + Free Phosphate Energy for Muscles Pyruvic Acid (no oxygen) Fats ( and O2) + Protein (emerge ncy ATP source) Citric acid cycle Hydrogen ions Electron transport chain ATP for Muscles ATP for Muscles 1. O2 enters the system, stopping the breakdown of glycogen to lactic acid 2. With oxygen, glycogen breaks down into: ATP + CO2 + H20 3. These byproducts are easier to get rid of CO2 is expelled by the lungs H2Ο is used in the muscle 15
4.Anaerobic Energy System = Carbohydrates are the only fuel source 5.With prolonged exercise, Carbohydrates are the first fuel choice, as exercise continues, FAT becomes predominant 6.Protein is not a main fuel source except in an emergency With Oxygen Glucose + O2 = 36ATP + H2O + CO2 Fatty Acids + O2 = 129ATP Body Fat is a great source of ENERGY Oxygen Deficit = The body can not supply enough O2 to the muscles that the muscles demand When the muscle does not get enough oxygen, exhaustion is reached causing immediate and involuntary reduction in intensity 16
Aerobic Capacity represents the ability of the body, to intake, transfer and consumption of O2 per time unit (L/min) As big the AC is, so is the ability of Work production (energy) from a person The AC is based on the harmonic collaboration of the Ventilation, Cardio-Vascular and Muscular Systems 17
The term Anaerobic Capacity describes the total of energy (ΑΤΡ) which comes from PCr and the Carbohydrates who are stored as glycogen into the muscles Normally, the AnC is directly affected from the age (decline of6% every year after 20 ο y) and indirectly affected from the muscle mass, the muscle fibers type, the energy stores of the metabolism and the tolerance of the person 18
Muscle strength is the ability of a person to overcome or resist the body weight and other external loads, with the energy of his muscles and is one of the main elements of Fitness We can see 3 expressions of strength: Maximum/absolute strength, Power or force-velocity and strength endurance (stamina) 19
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Energy is the capacity to do work. We need energy for : Basal Metabolism Basal Metabolic Rate- BMR: energy required for activity of the internal organs and maintaining of body temperature. Physical Activity-Work Metabolizing of Food Calorie: unit used to measure energy Kilocalorie is a unit of energy commonly used to express energy value of food. Food energy is the amount of energy in food that is available through digestion. The energy value of food indicates its value to the body as fuel. 22
Sum of all internal working activities of the body at rest Expressed as kcal/day Basal Metabolic Rate (BMR) is similar to RMR, but requires complete physical rest (difficult to achieve) Keeping the Basal Metabolic Rate (BMR) as high as possible is vital when it comes to weight loss and maintaining healthy body fat levels 23
Exercise/Work: This is one of the biggest factors that influence BMR. Hormones: an increase in thyroid hormones increases BMR, decreased levels of the hormone lower BMR Body Temperature: Excessive heat or cold raise BMR Gender: Males tend to have higher basal metabolism than females due to an abundance of hormones such as testosterone ad elevated levels of muscle mass compared to females Age: as we get older basal metabolic rate becomes increasingly slower. Surface Area: Taller individuals have a higher BMR compared to shorter individuals 24
The ratio of fat tissue to lean body mass (muscle, bone, and organs) Usually expressed as percent body fat Important for measuring health risks associated with too much body fat Two types of fat make up total body fat Essential fat Found in bone marrow, heart, lungs, liver, spleen, kidneys, intestines, muscles, and central nervous system Women have 4 times more essential fat than men Stored fat Found in adipose tissue Subcutaneous fat located under the skin Visceral fat stored around the organs in the abdominal area 25
In negative energy balance, fatty acids are released from adipose cells Used as fuel and cells shrink In positive energy balance, fat accumulates and adipose cells expand Brown adipose tissue (BAT) is another type of fat tissue made up of specialized fat cells Contain more mitochondria and rich in blood Function is to generate heat Found primarily in infants 26
Body mass index is a useful indicator of healthy weight for most people Body mass index (BMI) calculates body weight in relation to height BMI = body weight (in kilograms) / height2 (in meters) BMI = body weight (in pounds) 703 / height2 (in inches) Healthy weight BMI 18.5 24.9 Overweight BMI 25 29.929.9 Obese BMI 30 27
Metabolic Equivalent Term Expresses the energy cost of physical activities and is defined as the ratio of metabolic rate (and therefore the rate of energy consumption) during a specific physical activity to a reference metabolic rate 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2/Kg/min (It differs with thyroid status, post exercise, obesity, disease states) 2 2 METs = 2 mph on level 4 4 METs = 4 mph on level < < 5METs = Poor prognosis if < 65; 28
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Elevated HR cannot maintain energy equilibrium insufficient blood supply to heart may increase risk of heart attack in at-risk individuals Elevated Respiratory Rate chest pain in at-risk individuals loss of fine control General and Localized Muscle Fatigue insufficient oxygen -> anaerobic metabolism -> lactic acid - > pain, cramping A fatigued worker is less satisfied, less productive, less efficient, and more prone to errors 32
Task demands can be evaluated the same way that maximum aerobic capacity is evaluated by direct measurement of the oxygen uptake of a person performing the task. Indirect methods for estimating task demands: Tabular Values Subjective Evaluation Estimate from HR Job Task Analysis More Complex More Accurate 33
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Circadian rhythms are physical, mental, and behavioral changes that follow a daily cycle. They respond primarily to light and darkness in an organism's environment. Sleeping at night and being awake during the day is an example of a light-related circadian rhythm. A part of hypothalamus (suprachiasmatic nucleus or nuclei (SCN)), controls the circadian rhythm. That said, outside factors like lightness and darkness can also impact it. When it s dark at night, the eyes send a signal to the hypothalamus that it s time to feel tired. The brain, in turn, sends a signal to the body to release melatonin, which makes the body tired. That s why the circadian rhythm tends to coincide with the cycle of daytime and nighttime (and why it s so hard for Shift Workers to sleep during the day and stay awake at night). 36
The circadian rhythm works best when the worker has regular sleep habits, like going to bed at night and waking up in the morning around the same times from day to day (including weekends). When things get in the way, like jet lag, daylight savings time, or TV that keeps him up into the wee hours of the morning, could disrupt the circadian rhythm, which makes the worker feel out of sorts and can make it harder to pay attention If the worker has control over the work schedule, could make the adjustment easier: Night shifts Must try to keep the same sleep and wake times each day, even on the days off. This will help regulate the circadian Rythm, improve the sleep quality, and also help him to be alert during the shift. Rotating shifts Must rotate shifts clockwise. A schedule that rotates clockwise is usually easier to adjust to. This means it s preferable to go from a day shift, to an evening shift, to a night shift, rather than rotating the other way, or rotating without a pattern. To prepare for a new shift, should adjust the sleep and wake time gradually. If the worker begin adjusting the sleep and wake time for three days prior to the shift, it will be a smoother change. If he rotates clockwise, this will mean he must delay the bedtime and wake up time by an hour or two each night (depending on the new schedule). 37
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