DEFINITIONS CHAP 11 PE
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- Non-steroid hormones
- cannot pass easily through cell membranes. They are secreted by the thyroid gland and the adrenal medulla. Non-steroid hormones bind with receptors on the cell membrane.
- The regulation of hormone release works similar to a home thermostat that controls a furnace. This is called
- a negative feedback system.
- Steroid hormones are
- easily diffused through cell membranes and are secreted by the adrenal cortex, ovaries, testes, and the placenta. Steroid hormones enter the targeted cell and bind with receptors within the cell.
- ADH (antidiuretic hormone)
- secreted by the pituitary gland minimizes the risk of dehydration during periods of heavy sweating and hard exercise.
- Growth hormone (secreted by the pituitary)
- levels are elevated during aerobic exercise and directly stimulate fat metabolism.
- ST fibers
- have high aerobic endurance
- The thyroid gland
- regulates metabolism and calcium absorption. Bone formation increases during extended periods of exercise.
- The pancreas is responsible for two major hormones:
- insulin and glucagons. Insulin and glucagons increase the levels of glucose circulating in the blood.
- The kidneys have a strong regulatory influence on blood pressure.
- Hormones secreted by the kidneys help maintain plasma volume and blood pressure.
- Cells generate ATP by three methods:
-
1. The ATP-PCr system – A simple anaerobic energy system that functions to maintain ATP levels. Breakdown of phosphocreatine frees one group of phosphate which then combines with ADP to form ATP.
2. The glycolytic system – A system that produces energy through glycolysis.
3. The oxidative system – The body’s most complex energy system, which generates energy by disassembling fuels with the aid of oxygen and has a very high energy yield. - There are several ways to measure energy use during exercise.
-
Measure the heat generated within the body
Measure the respiratory gas exchange
Measure the isotopic diffusion - The rate at which your body uses energy is
- your metabolic rate.
- Four factors that can influence the basal metabolic rate.
-
age
body temperature
stress level
hormones - Some factors that influence aerobic fitness are
- heredity, training, gender, body fat, and level of activity.
- Causes of fatigue focus on:
-
the energy systems
the accumulation of metabolic by-products
the nervous system
the failure of the fiberÂ’s contractile mechanism. - A muscles ability to maintain action for an extended period of time is termed
- muscular endurance
- Muscle strength is a result of
- resistance training and recruitment of additional motor units. A permanent increase in muscle size is due to an increase in either the number of muscle fibers or the size of the existing muscle fibers.
- Autogenic inhibition
- is the bodyÂ’s safety mechanism to prevent the muscles from exerting more force that the skeleton and connective tissue can tolerate.
- Acute muscle soreness is
- the pain felt during and immediately following exercise
- actual muscle membrane damage
- Delayed-onset muscle soreness is felt a day or two after a heavy bout of exercise
- When designing a resistance training program, the first step should be a needs analysis that includes the following:
-
What major muscle groups need to be trained?
What method of training should be used?
What energy system should be stressed?
What are the primary sites of concern for injury prevention? - Upon completion of the needs analysis, your exercise prescription should include the following:
-
The exercises to be performed
The order in which they will be performed
The number of sets for each exercise
The rest periods between sets and between exercises
The load to be used (amount of resistance) - Strength development
- is optimized by few repetitions and high resistance.
- muscular endurance.
- Many repetitions and low resistance optimize
- The program should include periodization with two to three cycles per year. Each periodization will have five phases.
- Resistance training should be as sport specific as possible
- The basic unit of the nervous system is the NEURON.
-
A neuron is composed of three regions:
Soma or cell body – contains the nucleus
Dendrites – many, receive sensory stimuli
Axon – one, conducts impulses away from the cell body - FT fibers are
- best suited for strength and explosive performance.
- Muscle is comprised of three essential parts:
-
Epimysium – surrounds the entire muscle, holding it together
Perimysium – surrounds small bundles of fibers
Endomysium – connective tissue covering each muscle fiber - Motor impulses that trigger muscle response are complex. 2 key chemicals initiate the response including
- ACH (acetylcholehene, a neurotransmitter substance) and calcium ionsÂ…
- Coordinated movements require the use of opposing muscle units;
- agonists and antagonists, and synergists for assistance.
- Muscles can be categorized into 3 types of actions:
-
Concentric (exertion of force while shortening)
Static (isometric or exertion of force while static)
Eccentric (exertion of force while lengthening) - Breathing problems associated with exercise include
- dyspnea, hyperventilation, and performance of the Valsalva maneuver.
- On the average, the blood volume for
- men ranges from 5 to 6 L and in women 4 to 5 L.
- Muscle activity often results in
- an accumulation of lactate and hydrogen, which can impair energy metabolism and reduce muscle contractile force.
- The pH of body fluids is controlled by:
-
Chemical buffers - bicarbonate, phosphates, and proteins.
Pulmonary ventilation
Kidney function - Lactate and hydrogen accumulate in the muscle, in part because
- they do not freely diffuse across fiber membranes. Lactate level is best returned to normal level by active recovery rather than passive recovery.
- Air pollutants such as carbon monoxide, ozone, and sulfur dioxide can
- impair athletic performance.
- Arrhythmia is
- an irregular heart rhythm. The heart's function may be normal, but its timing is altered. This can affect the circulation. Symptoms include fatigue, dizziness, lightheadedness, and fainting.
- Diastole is the relaxation phase and systole is the contraction
- phase of the cardiac cycle.
- The blood transports .
- nutrients and metabolic waste products, helps regulate body temperature, and helps maintain the body's acid-base balance
- The average adult body contains
-
5L of blood. Our total blood volume is pumped through our hearts once every minute.
The vascular system is comprised of:
Arteries - carry blood away from the heart
Arterioles
Capillaries
Venules
Veins - carry blood towards the heart - Atherosclerosis
- is a narrowing of the coronary arteries.
- Aerobic exercises lead to improved blood flow and muscular endurance.
- Anaerobic exercises, on the other hand, lead to increased muscular strength.
- To overcome the force of gravity when blood returns from the lower extremities of the body there are three basic mechanisms to assist.
-
Breathing - pressure in the abdominal and thoracic cavities,
The muscle pump - contracted skeletal muscle,
Valves - series of one-way valves in the legs - There are four components of the cardiac conduction system.
-
Sinoatrial (SA) node - initiates the impulse for heart contraction, known as the heart's pacemaker, the rhythm it establishes is known as the sinus rhythm
Atrioventricular (AV) node - Receives impulse from SA and contracts almost immediately
AV bundle - sends the impulse toward the apex of the heart
Purkinje fibers - terminal branches of the AV node, transmits the impulse through the ventricles about six times faster than through the rest of the cardiac conduction system. - Numerous cardiovascular changes occur during exercise.
-
Heart rate - increases
Stroke volume - increases
Cardiac output - a product of heart rate and stroke volume, increases
Blood flow - patterns change, reduced blood flow to the kidneys, liver, stomach, and intestines, increased blood flow to the muscles and to the skin
Blood pressure - increased systolic, constant diastolic, With high intensity resistance training, blood pressure can increase dramatically.
The blood - oxygen exchange increases, plasma volume decreases, red blood cell concentration increases, becomes slightly more acidic - Repeated use of muscle fibers stimulates changes in their structure and function. Aerobic training produces changes in the
-
Muscle fiber type - Slow-twitch muscle fiber becomes larger. The percentage of slow-twitch and fast-twitch muscle fiber remains unchanged.
Capillary supply - number of capillaries increases allowing for greater exchange of gases, heat, wastes, and nutrients between blood and muscle
Myoglobin content - increases
Mitochondrial function, and - number and size increase improving the muscle's ability to use oxygen and produce ATP
Oxidative enzymes - increased activity, induces a glycogen-saving effect - Trained muscle
-
stores more glycogen than does untrained muscle. More glycogen storage allows the athlete to better tolerate the demands of training.
Has an improved capacity to use fat as an energy source. - There are various aspects of aerobic training to consider when analyzing the benefits.
-
Volume - Improvement in aerobic capacity is related to how many calories you expend during a training bout and how many times you train over a predetermined period.
Training intensity - speed and duration
Aerobic interval training and continuous training have the same benefits - Anaerobic training results in
- increased strength, efficiency of movement (improved skill and coordination), the muscles' aerobic capacity, and tolerance to lactic acid build-up, which reduces the risk of fatigue.
- Metabolic adaptations to training
-
Increases the lactate threshold
Resting metabolic rates are elevated - The respiratory system
-
Brings oxygen into the body
Delivers oxygen to our muscles
Rids the body of carbon dioxide
Has a role in maintaining acid-base balance - Hemoglobin
- carries the oxygen. Exercise decreases the muscle pH and raises the temperature, which allows more oxygen to be unloaded to the muscle.
- The rate of oxygen delivery and uptake depend on three major variables:
-
Oxygen content of blood
Amount of blood flow
Local conditions - hypobaric enviornment-
- low atmospheric pressure
- hypoxia-
- oxygen deficiency
- microgravity-
- (reduced gravity
- Acute altitude (mountain) sickness
- illness characterized by headache, nausea, vomiting, dyspnea, and insomnia. typically begins 6 to 96 h after one reaches high altitude and last several days
- DECOMPRESSION SICKNESS (BENDS)-
- a condition in which bubbles of nitrogen are trapped in the blood and tissues during a too-rapid ascent from depth during diving, characterized by servere discomfort and pain
- erythropoietin
- the hormone that stimulates erythrocyte (red blood cell) production
- High-altitude pulmonary edema (HACE)
- leads to coma and death
- Exercise in Hypobaric, Hperbaric and Microgravity Environments
-
Hypobaric- an enviornment, such as that at high altitude, involving low atmospheric pressure.
Hperbaric- an enviornment, such as that underwater, involving high atomospheric pressure.
Microgravity- an enviornment in which the body experiences a reduced gravitional force. - Conduction
- – the transfer of heat from one material to another through direct molecular contact. Permits the transfer of heat from your skin to materials that contact it.
- Convection
- – moving heat away from one place to another by the motion of a gas or a liquid across the heated surface. A cool breeze moving over the skin sweeps away the air in contact with the skin.
- Radiation –
- is the primary method for releasing the bodyÂ’s excess heat at rest. The nude body loses about 60% of its excess heat by radiation. If the temperature of the surrounding objects is greater than that of your skin, your body will experience a net heat gain via radiation.
- Evaporation
- - is the primary avenue for heat dissipation during exercise. As body temperature rises, sweat production increases.
- thermoregulatory center
- is located within the hypothalamus
- Physiological responses to exercise in the heat
-
Cardiovascular - demand of muscles impairs heat transfer to the skin, raises the heart rate, best endurance performances are achieved in cool climates
Energy production - can hasten glycogen depletion and increase muscle lactate contributing to the feeling of fatigue and exhaustion
Body fluid balance – loss of electrolytes, high rate of sweating reduces blood volume, reduced loss of urine - Health Risk
-
Heat cramps – probably caused by dehydration and mineral loss, administer fluids or a saline solution
Heat exhaustion – fatigue, breathlessness, dizziness, vomiting, fainting, cold and clammy or hot and dry skin, weak and rapid pulse Treat by moving person to a cooler location, elevating the legs, and administering salt water.
Heat stroke – life threatening, seek immediate medical attention
Hyperthermia – high body temperature, sensation of throbbing pressure in the head, chills - Physiological responses to exercise in the cold
-
Muscle function – weakened, fatigue occurs more rapidly
Metabolic responses – increased use of free fatty acids - Health risks during exercise in the cold
-
Hypothermia – low body temperature, heart rate drops, provide dry clothing and warm beverages, seek medical care in severe cases
Cardiovascular effects – decreases respiratory rate and volume
Frostbite
Repeated exposure to the cold may alter peripheral blood flow and skin temperatures, allowing greater tolerance. - VO2 max is defined as
- the highest rate of oxygen consumption attainable during maximal or exhaustive exercise.
- Numerous cardiovascular adaptations occur in response to training.
-
Heart size:
Weight and volume increase
Left ventricle wall thickens
Chamber size increases
Cardiac muscle hypertrophy
Stroke volume - substantially higher at rest and during maximal exercise, Larger people typically have greater stroke volumes.
Heart rate:
Resting rate decreases
Submaximal rate decreases proportionately with the amount of training completed
Maximal rate tends to be stable
Rate recovery period is shortened (The heart rate recovery curve is
an excellent tool for tracking a person's progress during a training
program.)
Cardiac output - increases considerably at maximal levels of exercise
Blood flow:
Increases, more capillaries, more effective redistribution of flow,
Total blood volume increases
Blood pressure - Resting pressure is lowered
Blood volume:
Increases primarily from an increase in blood plasma volume
Increases red blood cells
Decrease in blood viscosity - Respiratory adaptations to endurance training include
-
Total lung capacity remains unchanged
Residual volume decreases
Amount of air expelled increases
Amount of air exchange increases at maximal levels of exercise
Blood returning to the heart contains less oxygen