exercise science notes (1).pdf

Physical Activity - any body movement that requires work form your body/skeletal muscle - Ex. play, walking to class, yard work Exercise - planned, structured, and purposeful physical activity that is intended to increase fitness - Ex. resistance training, running, cycling Exercise Science...

Physical Activity - any body movement that requires work form your body/skeletal muscle - Ex. play, walking to class, yard work Exercise - planned, structured, and purposeful physical activity that is intended to increase fitness - Ex. resistance training, running, cycling Exercise Science - the scientific study of human movement performed to maintain or improve physical fitness Major Disciplines Exercise Physiology Biomechanics Motor Control - Motor learning Athletic Training Sports & Exercise Psychology Community Wellness/Health Physical Activity Intro To Biological Function Mass - amount matter - Base unit - gram (g) - Kilogram (kg) more important to us - Convert - 1 kg = 2.2 lbs - Ex. 180 lbs = 81.8 kg (180lbs/2.2lbs/kg = 81.8 kg) Temperature - amount of heat energy - Base unit - Celsius - Conversion - 1 degree celsius = 1.8 degree fahrenheit - But don't forget 0 degrees celsius = 32 degree fahrenheit - Ex. 30 degrees celsius = 86 degrees fahrenheit - (30 degrees celsius x 1.8 degrees fahrenheit/celsius) + 32 = 86 - C to F - multiply 1.8 and + 32  - F to C - subtract 32 and /1.8 Examples 1. 234 lbs = 106.4 kg 2. 72 kg = 158.4 lbs 3. 95 kg = 209 lbs 4. 148 lbs = 67.3 5. 22 C = 71.6 F 6. 97 F = 36.1 C 7. 38 F = 3.3 C 8. 25 C = 77 F Human Survival Needs Body temperature - Relatively stable body temperature - Around 37 C (98.6 F) Atmospheric Pressure - Must be adequate for gas exchange - Maintain enough oxygen in our body - Decreases in pressure = decrease in oxygen per unit volume - “Thin air” Blood pH - Basic (pH of 7.4) - Measured in pH - pH - indication of the concentration of H+ in a solution Survival Needs Nutrients - Carbohydrates, proteins, lipids, and water - Micronutrients Body water - 50-80% of body mass - Most abundant single molecule in the human body Homeostasis Balance or stability of an environment Maintenance of a relatively stable internal environment - A dynamic state of equilibrium Homeostatic Control Negative feedback - Response to stimulus is to reverse changes and bring the body back to normal ranges - Very common Positive feedback - Accelerate response to stimulus - Rare in our bodies (blood clotting and uterine contractions) Homeostatic Imbalance - A disturbance in homeostasis can lead to disease or death - Heat stroke - Cardiovascular disease - Diabetes - Dehydration Sensory receptor examples Chemoreceptors - changes in chemical stimuli (o2, cO2, and pH) - In lungs, heart, muscles Osmoreceptors - changes in body fluid concentration (water) Pain Receptors - sense pain Mechanoreceptor - changes in body position (pressure & balance) Thermoreceptor - changes in temperature Baroreceptors - changes in pressure (BP maintenance) How does your body use water? Transport medium - Polar solvent (can dissolve things) - Nutrients - Gasses - Heat  High heat capacity - Prevents large changes in body temperature Digestion Chemical reactions Important Molecules in the Body Carbohydrates - Major source of cellular fuel - Eg. glucose, fructose - Structural molecules - Eg. cell makers for immunity Lipids (including fats) Major source of cellular fuel - Eg. triglycerides Structural molecules - Eg. phospholipids - Essential component of cell membrane (lipid bilayer) - Determines which molecules can enter and exit the cell Chemical messengers (hormones) - Eg. steroid hormones - Convey info Proteins Major structural component of body tissues Not an effective fuel choice Play a vital role in many cellular chemical functions - Act as enzymes, hormones, and antibodies Enzymes Biological catalysts (usually a protein) that function to increase the speed of reactions Bind to substrate at an active site to catalyze reactions Substrate - a molecule on which an enzyme acts Catalyze - cause an action to begin/accelerate Enzymes - a catalyst used to increase speed of reaction Anabolic - a “building” reaction Catabolic - a “breaking” reaction Nucleotide - structural unit of nucleic acid Active Site - point at which substrates bind to enzyme Adenosine triphosphate (ATP) ATP is based on a nucleotide - Base (adenine) - Sugar (ribose) - Phosphate group Cellular currency for energy - i.e. ATP = energy What Does ATP do? Chemical work - Provides energy needed to drive energy-absorbing chemical reactions Transport work - Getting protein into the cell - Drives the transports of certain solutes Mechanical Work - ATP activates contractile proteins in muscle cells can shorten and perform mechanical work The Human Organism - Cells to Organ Systems working together Cell theory The cell is the basic structural and function unit of life Organismal activity depends on individual and collective activity of cells - Continuity of life has a cellular basis Major Areas of the Cell Plasma membrane Cytoplasm Nucleus Transport: Moving Matter and Energy Gradients An unequal distribution of particles or energy 3 main types - Chemical concentration - Pressure - Temperature diffusion - movement in molecules from an area of high concentration toward low concentration Organ Systems Interrelationships Organ systems work cooperatively to perform functions necessary to sustain life Control Systems 1. Nervous system - Wired, fast response system of control 2. Endocrine system - Wireless, slower system of control - May lead to larger changes Nervous system Composed of brain, spinal column, and nerves Fast-acting control system of the body Responds to stimuli by activating muscles and glands Endocrine system Composed of various glands spread throughout the body  Slow acting control system of the body Release hormones into the blood system to send signals around the body Cardiovascular system Delivery system within the body The heart pumps blood The blood vessels transport blood throughout the body Respiratory system Exchanges of gasses with environment Keeps blood supplied with oxygen and removes carbon dioxide Helps control pH Skeletal muscular system Means of interaction with the environment Composed of muscles and tendons - Allows manipulation of the environment, locomotion, and facial expression - Breathing - Maintains posture Skeletal System Forms main structure of the body Protects and supports body organs Provides the framework for muscle Stores minerals Site of blood cell formation Muscles of Human body Skeletal Cardiac (walls of the heart) Smooth Functions of all types of muscle - Produce tension (contract)  - Produce heat Special modifications of the skeletal muscle cells 1. Multinucleated - Large elongated cells with high energetic demands - Enables muscle to acquire more oxygen and nutrients - Facilitates repair of injured/damages muscle 2. Myofibrils - groups of sarcomeres 3. Sarcomere - Allows them to contract 4. Sarco… - Sarcolemma - cell membrane - Sarcoplasm - cytoplasm of muscle cell - Sarcoplasmic reticulum - smooth ER 5. Myoglobin - Supplies oxygen to cells Each myofibril has myofilaments (actin and myosin). A bunch of myofibrils make up the sarcolemma Myofibrils - rod-like contractile elements - Densely packed within the cell - Most of the muscle volume Myofibrils within a fiber are perfectly aligned in repeating series of dark (thick) A bands (myosin) and light (thin) I bands (actin) is evident - Composed of many sarcomeres - Striations Sarcomeres Smallest contractile unit of a muscle The region of a myofibril between two successive Z discs Composed of myofilaments made up of contractile proteins - Myofilaments are of two types - thick and thin Sarcoplasmic Reticulum (SR) Smooth ER that surrounds each myofibril functions  - Stores and releases calcium ions to signal for contraction Muscle Force Production 1. Cross Bridge Formation - Myosin head attaches to actin (cross bridge is formed) 2. Power Stroke - ADP is released and the activated myosin head pivots, sliding the thin myofilament towards the center of the sarcomere (sarcomere gets smaller) 3. Detachment of cross bridge - ATP attaches to myosin head and detaches the cross bridge (bond between actin and myosin is broken) 4. Reactivation of myosin head - ATP is hydrolyzed (broken into ADP + Pi) and energizes the myosin head (brings it back to its crooked position) Sliding Filament Theory - Myosin pull actin toward center of sarcomere = muscle contraction Controlling of Muscle Fibers Motor unit - one motor neuron and all the skeletal muscle fibers innervated by that neuron - Smallest functional unit - Single muscle fiber can only be innervated by one motor neuron - Single motor neuron can innervate multiple muscle fibers - Important for coordinated movement, strength development, and movement efficiency Skeletal Muscle Fiber Types Type 1 - Slow Twitch (long distance) Slow contraction time Low peak forces High resistance to fatigue Energy delivered by aerobic metabolism Rich vascular system Type 2a - Fast Twitch Resemble slow twitch fibers Have well developed glycolytic pathways Moderate forces Moderate contraction times Types 2x - Fast twitch (sprinters) Specialized for high speed contraction Fatigue easily High peak forces Energy delivered for anaerobic metabolism Primary Control of Force Production Motor Unit Recruitment Recruit an increased number motor units to produce greater force and speed Greater strength of action potential - more recruitment Size Principle Motor units recruited from smallest to largest depending on the force needed - Important for strength, hypertrophy, and rate of force development Recruit slow twitch fibers for low force tasks Need to recruit both slow and fast twitch fibers for high force tasks Muscle Specific Motor Units Soleus - Important for posture - Constantly used standing - Comprised mostly of small units (type 1) - 180 muscle fibers per motor neuron Gastrocnemius - Powerful, fast movements - Large units (Types 2a and 2x) - 1000-2000 muscle fibers per motor neuron  Extraocular - Control eye movements - 84% fast fibers (likely type 2a) - 3 muscle fibers per motor neuron Energy Production Processes to replenish ATP Phosphocreatine - anaerobic/fast Glycolysis - anaerobic/fast mitochondrial/aerobic respiration ATP Production: Enzymatic pathways - Sequence of enzyme-catalyzed reactions that lead to the conversion of a substance into a final (end) product Enzyme outside of Hoemrostatric Environment Enzymes only function under small range of certain conditions - pH - Temperature Conditions outside specific range = enzymes can’t function - Can't bind to substrate so reaction is slowed Phosphocreatine System Anaerobic ATP yield: 1 ATP: 1 PCr Duration: up to 10 seconds Because ATP stores are limited, this pathway is used to reassemble ATP quickly CR P + ADP —-> ATP + CR Glycolytic System Anaerobic when directly utilizing Glycolytic enzymes in cytosol ATP yield: 2 ATP usable per glucose  Duration: 1-2 min Breakdown of glucose via glycolysis Aerobic/Oxidative System (aerobic = with oxygen) ATP yield: depends on substrate - 32 ATP/1 glucose - 100+ ATP/ 1 Fatty Acid - Most of this ATP comes from the Electron Transport Sys. Duration: steady supply for hours Skeletal System (Bones) in Exercise 1. Used as for levers for our muscles to pull on to produce movement 2. Provides general support 3. Protect organs - To a point… brain trauma still happens Composed of bones, cartilage, and ligaments Bones as levers for movement Wolfe’s Law: bone will remodel (adapt/change) based on the stress/load under which it is places Nervous System Voluntary and Involuntary control over the body - Central Nervous system - Brain and spinal cord - Peripheral nervous system - Autonomic nervous system (communicates with internal organs and glands) - Sympathetic Division (arousing) - Parasympathetic Division (calming) - Somatic nervous system (communicates with sense organs and voluntary muscles) - Sensory (afferent) nervous system (sensory input) - Motor (efferent) nervous system (motor output) Control of Muscle Fibers Motor Unit - one motor neuron and all the skeletal muscle fibers innervated by that neuron Smallest functional unit Single muscle fiber can only be innervated by ONE motor neurons Single motor neuron can innervate multiple muscle fibers Nervous System in Exercise Voluntary control of skeletal muscle Both Autonomic (nervous) and endocrine (hormone) signals lead to the following major changes: - Increased blood flow (multiple reasons) - Increased Ventilation (breathing) - Allows more exchange of gasses - Sweating - Release of Epinephrine Signals in Body Around Exercise Bouts Sympathetic/Endocrine response - Thinking about exercise start the changes - Byproducts from contracting muscles lead to the major changes - Epinephrine release (among other hormones) Chemical changes - Byproducts from active skeletal muscle get into bloodstream and lead to increased activity of other systems Cardiovascular System A pump connected to a closed system of tubes used to move blood around the body Important substances moved around the body during exercise: - Nutrients - Wastes - Gasses - Heat Blood 5 liters in the human body Consists of plasma, white blood cells (leucocytes), platelets, and erythrocytes (red blood cells) The Heart (2 pumps in 1) Heart - creates pressure to move blood through vessels Right and left side acts as pumps for separate set of vessels - Right side - pump for pulmonary circuit (lungs) - Left side - pump for systemic circuit (everything) Primary Vessel Types 1. Artery: carries blood away from the heart 2. Vein: carries blood back to the heart 3. Capillaries: thin vessel to exchange nutrients and wastes with tissues - Also the primary turn around point for blood flow direction Cardiac Output Cardiac output (CO) = amount of blood ejected from the heart in one minute CO = Heart Rate x Stroke Volume - HR = The number of times the heart contracts per minute - SV = The volume of blood pumped by the heart per beat Increase CO during moderate: SV inc more than HR Increase CO during high intensity: HR + SV inc same Blood Pressure Systolic - Pressure in arteries when the heart is contracting Diastolic - Pressure in arteries when the heart is relaxed  Systolic increases in exercise - More pressure = higher blood flow Diastolic remains stable - As long as you breathe (don’t hold your breath) Key Cardiovascular Changes During Exercise Increase CO - Increase HR - Increase SV Increase BP - Mainly systolic Redirect blood flow around the body - Shunt blood to active muscle, heart, and skin (usually) Respiratory System Exchange gasses between blood and our environment - Bring in oxygen - Needed for efficient energy production - Removes carbon dioxide - Keeps body’s pH under control - Lower CO2 allows carbonic acid to dissociate into bicarbonate (HCO3^-) + H^+ Oxygen Transport in blood - 1 primary mechanism CO2 transport in Blood - Dissolved CO2 - Chemically modified - Protein-bound Key respiratory response During Exercise Respiratory centers are excited due to increased CO2 in the blood - Increased depth of breathing - Increased rate of breathing Note:  CO2 is the primary reason increases in ventilation during exercise O2 is the trigger for increased ventilation at altitude and with respiratory diseases Skin in Exercise Attenuates change in body temperature - Both hot and cold climates Works with cardiovascular system to control heat transfer Covered in Environmental Effects on Exercise lecture Key Skin Responses During Exercise Due to increase in temperature (heat from energy metabolism) - Increased blood flow to skin - Increased sweating Fluid in Human Body ⅔ in cells ⅓ outside of cells - Interstitial fluid Urinary System Filters the blood to make urine Important in maintaining: (during exercise) - Fluid levels - pH (along with 2 other mechanisms - Respiratory system, integumentary system Kidneys during exercise Monitors blood concentration and pH During exercise: - Reabsorbs more fluid - Secretes more H+ Digestive System Slows during exercise Intake nutrients to remove solid waste  - Even with decreased blood flow during exercise Relating to exercise, need the nutrients for: - Fluid levels (hydration) - Electrolyte balance - Energy production Endocrine System Involuntary hormonal responses to exercise Helps control: - Blood flow - Urine production - Energy metabolism Epinephrine actions during exercise: - Increases heart rate - Makes heart contract faster - Dilated blood vessels in skeletal muscle - Increases blood flow Acute fatigue inability to maintain a given output Reasons for fatigue relative to intensity High intensity short activity - Short time span Reasons for fatigue - CP system depleted slowing ATP resynthesis - Build up of: - Acidic byproducts - Hydrogen builds up Lower intensity long activity - Long time span Reasons for fatigue (should be able to make ATP fast enough)  - Run out of fuel stores for energy pathways - Glycogen stores depleted - Dehydration - Heat - Damage to muscles Training and Adaptation Acute Response vs. Training Adaptation Acute Response Occurs to: - Meet metabolic demands - Maintain homeostasis Lasts for short period of time (less than 24 hours) During exercise, our heart rate increases Training Adaptation Occurs when the body is stressed on a regular basis (exercise) Body adapts to become more efficient when responding to stress Facilitated via an upregulation (increased production) of enzymes, hormones, and neurotransmitters Long term Ex. decrease in heart rate over time due to adapting to exercise environments Components of Fitness - Health related 1. Muscular Strength - Ability to apply force during an activity 2. Muscular Endurance - Muscle ability to resist fatigue 3. Cardiorespiratory Endurance - Ability of the cardiovascular system and the respiratory system to supply tissues with nutrients to resist fatigue 4. Flexibility - Ability to perform movements through a range of motion - Lengthening a muscle versus need to strengthen a muscle 5. Body Composition - Relative amount of body tissues - Represented in different ways  Components of Fitness - Performance Related 1. Agility - Rapid whole-body movement with change of velocity or direction in response to a stimulus 2. Speed - Ability to perform a movement within a short period of time 3. Power - Rate at which one is able to exert maximal force 4. Balance - Ability to maintain line of gravity within base of support 5. Coordination - Ability to use the senses, together with body parts to perform motor tasks smoothly and accurately 6. Reaction Time - Time elapsed between stimulation and the beginning of the reaction to it Principles of Training 1. Specificity - fitness/performance improves through training movement patterns and intensities for a specific task/sport (you gotta do what you wanna get) - Speed of a movement, muscles used, etc. - Double edged sword… too much of the same thing tends toward injury/overuse 2. Overload - Exposure of tissues to greater than accustomed-to training stress - Frequency, intensity, and duration (if your body want to do more, then you gotta do more) 3. Progression - Gradual and systematic increases in training stress to maintain tissue overload - Adaptation occurs… moderate intensity becomes low intensity 4. Individuality - modification of training to account for a person’s individual capacities for and response to training - Response to training is not one size fits all 5. Reversibility - Withdrawal of tissue loading results in loss of adaptations (use it or lose it) 6. Recovery - Individuals need adequate time to recover for adaptation and repair to occur - Important part of programming for fitness performance - Time off or low intensity active recovery Components of a Workout: Warm Up (should be sport specific) Benefits: 1. Improved performance by 1-10% (greater in explosive sports) 2. Gets the head in the game 3. Primes the machine Mechanisms: Increased blood flow to active muscle (vasodilation) - Helps limit blood pressure spikes in people with hypertension Increased energy pathway enzymatic activity Increased compliance and energy return in tendons Improved reaction time via nerve pathway pre-activation Components of a Workout (Training) Benefits 1. Improve fitness 2. Become faster, stronger, better Focus on component of fitness Utilize the principle of specificity and overload Follow the FITT principle What is the FITT Principle? Training prescription to improve health and fitness F = frequency I = intensity T = time T = type Alteration in these components help achieve the overload & progression principle FITT Example of Cardiac Exercise F: 3-5 days per week I: 60% of HRmax T: 30 minutes T: whole body exercise that utilizes large muscle groups Components of a Workout: Cool Down - Return cardiovascular function to normal levels slowly - Most important in older individuals with hypertension - Sudden stoppage of vigorous activity can lead to blood pressure drop and syncope (fainting) - Great time for flexibility training - Muscles and connective tissue warm and compliant Simple Exercise Programming vs. Periodization Basic Programming Manipulation of training principles that are needed to bring about specific adaptations in fitness/performance Periodization A cycle/phase (i.e.-period) based training program designed to optimize performance and avoid overtraining - Typically designed for peak performances occurring on specific dates (Olympics, nationals, sectionals, etc.) Traditional Periodization Cycle Macrocycle - full year or - Season plan Mesocycle - Weeks to months Microcycle - Usually less than 1 week Daily changes Common Methods to Measure Intensity in Endurance Training Heart Rate Monitors Chest strap vs optical heart rate monitors - Both accurate if you have a current high end model  - Chest straps were more accurate during exercise until around 2021-2022 Rating of Perceived Exertion (RPE) Measured of perceived intensity Based on HR Easily used in the field Used most often with HR The Metabolic Cart Used to measure gas exchange during ventilation - At rest or during exercise Measures oxygen consumed and carbon dioxide produced - Compares room air versus the air you exhale to determine the difference and provide values All values can be reported in Absolute or Relative numbers - 75 liters (L) of air moved or 75 L/min Oxygen Consumption (VO2) - Rate of oxygen consumed by the body Common measures Oxygen consumption - Absolute: oxygen consumed per minute - L/min - Relative: oxygen consumed per minute relative to body mass - ml/kg.min - Sedentary person - around 35 ml/kg/min - Elite endurance athletes - around 75-85 ml/kg/min Absolute carbon dioxide produced - L/min Respiratory exchange ratio (RER) - Ratio: CO2 produced/O2 consumed  - Estimate carb vs fat utilization Absolute VO2 = Volume of O2 consumed (L/min) Not based on size of individual Relative VO2 = Volume of O2 consumed based on size of individual (mL/Kg/min) If an 80kg person and a 60kg person have a VO2 max of 2.8 L/min, do they have the same fitness level? Example: 2.8 L/min ÷ 80 kg = 0.035 L/kg/min 0.035 L/kg/min X 1000 mL/L = 35 mL/kg/min What is the relative VO2max of the 60 kg person? How Do We Determine VO2 Max? VO2 max = max rate of oxygen consumption - Point at which O2 consumption doesn’t increase with further increase in intensity Lactate threshold Point at which blood lactate accumulation increases markedly - Interaction of aerobic and anaerobic systems - Measure of anaerobic shift point - Good indicator of potential for endurance exercise Usually expressed as percentage of VO2max Excess Post-Exercise Oxygen Consumption (EPOC) Why do you keep breathing heavily for a period of time after you stop exercising? - Replenish ATP/PCr stores - Convert lactate to glycogen - Replenish hemo/myoglobin Adaptations to Endurance Training Cardiovascular Adaptations Increased blood volume Increase in red blood cell count Increased stroke volume - Heart size change Increased cardiac output - Due to changes in SV Improved control of blood flow around the body - Shunt blood to active muscle Decrease in heart rate at rest and at intensities below max - Resting lower - Lower for a given intensity - Max HR does not change Why is HR lower? - Since the stroke volume is up, the heart rate is able to do down Blood Pressure Changes Blood pressure will decrease with training Due to: - decreased vascular resistance (less vasoconstriction) - Decreased sympathetic input - Decreased Hormonal axis for fluid retention - Arterial compliance (how stretchy the arteries are) - Lower resistance contributes decrease in HR and increase in SV Adaptations to Endurance Training: Skeletal Muscle Fiber type alterations - Small percentage of type 2x → type 2a Mitochondria - Increase in number - More aerobic enzymes for ATP production  Capillary (oxygen exchange) supply (capillary density) - Increased number of capillaries supplying each fiber Endurance Training Effects on VO2 and LT Increase in VO2max - Best indicator of cardiorespiratory fitness - *not necessarily performance* Increase due to cardiovascular and muscular changes - Increased cardiac output and capillary density - Increased mitochondria and oxidative enzymes Lactate threshold can increase to over 80% of VO2max Can run faster for longer without fatigue Causes of increase - Mitochondria and oxidative capacity Resistance Training Specifics How many Days/Week? Depends on training age/status and goal Up to 3 days/wk can be utilized for a given muscle group if you can cover appropriately - stress/adaptation response 1 day/wk can be enough to maintain strength gains - For around 2 months - 2-3 times per week recommended Adaptations to resistance training First 6 weeks of training is due to neurological changes Neural changes in Strength/Power Motor learning aspect - - Increased synchrony of motor units  Increased reciprocal inhibition - Relaxation of muscles on one side of the joint to allow for contraction on the other side Hypertrophy Acute/Transient Hypertrophy - “Pump” - Fluid accumulation in muscle organ Chronic hypertrophy - After months of training - Increase in protein synthesis that is reversible (use it or lose it) Can happen due to microtears in the muscle (untrained/extreme tension) - Activates an immune response to “heal” the muscle - Repair and rebuild happens - Delayed onset muscle soreness (DOMS) NOT lactic acid buildup Can be due to hypertrophy of muscle fiber - Increase in muscle cell size - More common Can be due to hyperplasia of muscle fibers - Increase in number of muscle cells Important training considerations of Hypertrophy Typically >65% of 1RM - generally meaning 15 reps or less per set Eccentric loading - Controlled lowering of the weight - Allows time for mechanical stimulus of growth Failure? - Close to failure is good for more people (within 1-2 reps of failure) - Bodybuilding may be a bit different Muscle Physical Alterations with Training Cross sectional area increase Small percentage type 2x decreases, percent type 2a increases with higher loads/slow speed (i.e. additional strength training) Small percent type 1 decrease percent type 2a increase with power/ballistic training Increased cross-sectional area of the muscle (hypertrophy, hyperplasia, or both) Selective hypertrophy of fast twitch fibers (2a mainly) More stores ATP and phosphate (enhanced anaerobic energy system) Environmental Exercise Physiology (heat and cold) Humans endothermic - Produce our own heat internally Homeothermic - Relative stable core body temperature in all environments - Core body temp: 36.5-37.5 degrees Celsius Body fluid - 60% of body weight Mechanisms of Heat Transfer 1. Radiation R - Energy transferred via infrared waves - 60% of heat loss at rest 2. Conduction C - Energy transfer via direct contract 3. Convection C - Energy transfer via mass motion of molecules 4. Evaporation E - Phase change of liquid to gas through the transfer of heat energy - 70-80% of heat loss during exercise Exercise in the Heat Body temperature increases due to: - Muscle metabolism - Amount of hed produced related to intensity - Environment - Mostly radiation - Heat stress Hot Environments can Differ Hot-Dry Environment - Very warm air - High solar radiation - Low humidity Hot-Wet Environment - Warm air - High humidity - Evaporation is less effective - Increased sweating and faster dehydration How do we Measure Heat Stress? Wet Bulb Globe Temperature (WBGT) - Measure of heat stress in direct sunlight - Takes into account: temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation) Heat stress differs from heat index - Heat index only uses temperature and humidity and is calculated for shady areas How is WBGT determined? 10% of air temperature 70% of natural wet bulb temperature 20% of black globe temperature How is WBGT used? Research Military  Athletics Worker safety Measurement of Temperature During Exercise Core temperature - Temperature pill - Rectal thermometer Skin temperature - Thermal sensors Acute Responses to exercise Heat Stress Cardiovascular response - Vasodilation of blood vessels in the skin - Increased heart rate (HR) for a given activity - Routing more blood to skin surface to release heat Sweating response - Increased sweating - Typical sweat rate during exercise 1.0-2.0L/hr - As sweat is ultimately produced in blood plasma, we see a decrease in plasma volume Sweat Patches Regional sweat rates Electrolyte concentration - Can differ by site Problems with Prolonged Exercise in the Heat During prolonged exercise in the heat, we can observe the following events taking place… Reduced muscle blood flow - Especially during high-intensity exercise as blood is sent to the skin High brain temperature reduced neuromuscular drive - Reduction in motor unit recruitment/coordination Dehydration - Large amounts of fluid loss Acclimatization (Adaptations) to Exercise in the Heat Blood volume Increases (via plasma volume) - Allows for better muscle and skin blood flow - Decreased heart rate for an exercise intensity Widespread sweating that starts earlier in exercise - Sweating begins at a lower body temperature - Sweat over larger area to dissipate heat (different sweating pattern) - Lower electrolyte concentration Safety Considerations for Exercise in Heat Humans are smart Choose time of day to exercise Drink water - -2% in body water loss before thirsty - Drink before thirsty Choose technical clothing over cotton Acute Response to Cold Initial response Vasoconstriction in the skin - Particularly the extremities - Attempt to retain heat by - Limiting radiation - Thicker insulation layer Non-shivering Thermogenesis - Brown adipose tissue (BAT) metabolizing fatty acids to increase heat production Shivering thermogenesis - Involuntary skeletal muscle twitches to increase metabolism for heat production - Asynchronous MU activation] Problems with Prolonged Exercise in the Cold Hypothermia - core body temperature below 35 degrees celsius Reduced dexterity in extremities (hands) - Due to reduced blood flow and slower nerve transmission Skeletal muscle function decreases  - Nerves and muscles slow - Altered fiber recruitment leading to decreased contractile force Risk of frostbite Chronic Adaptations to Exercise Cold Stress Extended col exposure leading to better function in the cold Lower skin temperature at which shivering beghins - Increased non-shivering thermogenesis Maintain higher hand and food temperature - Improved peripheral blood flow - Improving dexterity Improved ability to sleep in the cold - Due to reduced shivering Safety - Wet and Cold Water increases heat loss significantly - Especially moving water (convection) Water and clothes - Clothes getting wet will decrease insulation rate - If clothing is breathable, you will have increased cooling via convection and evaporation - Layers are important to control temp during weather training - Remove layers to limit sweating to keep from soaking clothes Exercise Physiology Definition: the effect of exercise on cells, tissues, organs, and organ systems Percent of People who meet PA: 28.3% of men and 20.4% of women meet the guidelines for both aerobic and muscle strengthening activities Clinical Exercise Physiology Subspecialty of exercise physiology of exercise physiology that investigates: - How exercise is affected by chronic disease - How exercise training is used to treat those chronic diseases Top 10 Chronic Diseases in the U.S. Obesity Arthritis Hypertension Hyperlipidemia Depression Asthma Heart disease Diabetes Malignant neoplasm stroke 55-62% of the people that have one of these chronic conditions have at least one more How do we measure risk? Body composition - Relative amount of fat, bone, muscle mass, and water within the human body - Ex. - BIA - DXA Anthropometric measures - Physical measures of a person’s size, form, and functional capacities - Ex. - BMI (height and weight) - Circumferences (waist) Big Takeaway: BMI is an easy-to-use measure that can predict relative risk of disease in the general population Body Composition Dual x-ray absorptiometry (DEXA or DXA) - Measures using x-ray radiation - The darker the tissue = more dense - Originally designed for bone density - Used now to determine - Fat mass - Lean mass  - Bone mass Bioelectrical impedance (BIA) - Measures electrical resistance - Fat is an insulator (doesn’t conduct electricity well) - Electrolytes and water (big components of muscle) conduct electricity well - Used now to determine - Fat mass - Fat free mass Obesity Definition - abnormal or excessive fat accumulation that presents a risk to health Adipose Tissue - what it normally does Energy homeostasis - Energy storage - Distribution of stored energy Secretes Hormones - Regulates glucose uptake - Regulates lipogenesis - Regulates appetite - Regulate insulin sensitivity Non-shivering thermogenesis Adipose Tissue - what can be harmful Ectopic deposits - When adipose tissue under the skin is “full” lipids begin to be taken up and build up at other organs, which can disrupt function Increases Inflammation - Increased recruitment of immune cells - Change in their function inside the tissue Insulin Resistance - Can lead to diabetes if untreated Atherosclerosis Breakdown of word - Athero = paste - Sclerosis = hardening Build-up of plaque inside the wall of a damages blood vessel Other risk factors - High blood pressure - High cholesterol - Smoking - Insulin resistance - Systemic inflammation Atherosclerosis - progression Symptom Progression - Fatigue - Headaches - Chest pain (angina pectorisis) - First with exertion - Can occur with typical ADL’s if not treated - Activities of Daily Living - Acute myocardial infarction (AMI) - AKA a heart attack Atherosclerosis - Does exercise affect it? Cardiac rehabilitation - Lowers LDL cholesterol - Improves blood pressure - Relieving symptoms - Building healthier habits - Reducing stress & improves mood - Increases strength to improve ADLs - Prevention of future events Diabetes Mellitus (DM) Breakdown of the word - Diabetes = siphon / to pass through - Mellitius = sweet  Disease with abnormally high blood glucose - Type 1: destroyed pancreatic cells that can’t produce insulin (usually auto-immune) - Usually diagnosed at a young age - Type 2: insulin resistance and impaired ability to control blood glucose - Mediated by genetics, diet, chronic inflammation and obesity - Usually diagnosed in adulthood Progression Prediabetes - 98 million american adults have prediabetes (⅓) - 80% are unaware they have it - Characterized by elevated blood sugar, but below the cutoff for diabetes - Generally reversible - If untreated, 5-10% annually progress to diabetes Type 2 prevalence - 9% of the total US population - 25% over age 65 How to Test for it Oral glucose tolerance test - 50g glucose in 250-300mL water - Blood glucose is tested over the next two hours - Normal = 200 mg/dL Complications Atherosclerosis - Coronary and systemic - Can lead to poor circulation and gangrene Neuropathy - Loss of feeling and motor control Glomerulosclerosis - Improper function of the blood vessels responsible for filtering blood  Diabetic retinopathy - Vision issues Diabetes Mellitus - Type 2 DM and Exercise Treatment Lifestyle Intervention - Diet - Low glycemic load diet - Exercise - Increase insulin sensitivity - Depletes sugar stores in the muscle and helps increase glucose uptake independent of insulin - Lowers blood pressure, lowers heart rate, and allows for better control of blood vessels - Likely to stop progression from prediabetes to diabetes Oral medication and insulin if severe diabetes develops Cancer Overarching term for >200 diseases that involve uncontrollable cell growth that can spread to other parts of the body Genetic mutation that results in disruption in the normal cell renewal process Cancer - what increases risk? Genetics Virus (HPV) Smoking Cells rapidly dividing UV radiation Chemicals Cancer - Can exercise affect certain types? Prevention - Examples of specific cancers that can be preventable with exercise - Bladder - Breast  - Colon - Endometrial - Esophageal - Kidney - Stomach Can be of benefit when supplemental to treatment Reduces anxiety Improves physical function and free living physical activity Reduced depressive symptoms Reduced fatigue