Nutrition CH 9

because sweat is hypotonic to the body fluids, the concentration of electrolytes in the blood and other body fluids actually

increases during exercise and makes the body fluids hypertonic. during moderately prolonged exercise, water rehydration maintains electrolyte balance. electrolyte supplementation is not necessary

Pre-cooling may be an effective ergogenic strategy for some athletes competing in heat because it _____.

increases heat storage capacity

When blood volume _______ with acclimatization, muscles receive more oxygen and skin cooling _______.

increases; increases

Which organ maintains body water at a normal level?

kidney

body water is maintained at a normal level through

kidney function

hypothermia

low body temp and rapid loss of temp control. this condition may also develop in slower runners during the later part of a road race under cold, wet and windy environmental conditions. when heat is lost more rapidly than it is produced through exercise. muscular incoordination and mental confusion are early signs of hypothermia

health benefits to drinking more water: lotan and others suggest that

low fluid intake may be associated with urinary system diseases

Since fat tissue is ____ in water content than/to muscle, females generally have less water mass than males.

lower

The following are prudent tips to prevent heat injury with exercise: 1-5

(1) check the temp and humidity conditions before exercising, even if the dry temp is only 65-75 degrees F, high humidity will increase the heat stress, warm humid conditions can also cause fatigue sooner (2) exercise in the cool of the morning or evening to avoid the heat of the day (3) exercise in the shade, if possible to avoid radiation from the sun. (4) wear sports clothing designed for exercise in the heat such as CoolMax type material. clothing should be loose to allow air circulation, white or a light color to reflect radiant heat and porous to permit evaporation. do not wear a hat if running in the shade but wear a loose hat if running in the sun (5) if you are running and there is a breeze plan your route so that you are running into the wind during the last part of your run

major functions of water in the body?

(1) water provides the essential building material for cell protoplasm, the fundamental component of all living matter (2) water cannot be compressed it protects key body tissues such as the spinal cord and brain (3) essential for the control of the osmotic pressure in the body (4) the main constituent of blood, the major transportation mechanism in the body conveying oxygen, nutrients, hormones and other compounds to the cells (5) essential for proper functioning of our senses (6) regulation of body temp

The following are prudent tips to prevent heat injury with exercise: 11-14

(11) avoid dietary supplements containing ephedrine. ephedrine is a potent stimulant that can increase metabolism and heat production, leading to an increased body temp during exercise in warm environments and predisposing to heat illness (12) if you drink caffeinated beverages, check your responses. current research indicates that caffeinated beverages may not affect hydration status or temp regulation during exercise. however, some individuals may respond directly to caffeine intake. caffeine can increase heat production at rest which could raise body temp before exercise (13) because alcohol is a diuretic, excess amounts should be avoided the night before competition or prolonged exercise in the heat (14) if you are sedentary, overweight, or aged you are less likely to tolerate exercise in the heat and should use extra caution

The following are prudent tips to prevent heat injury with exercise: 15-18

(15) be aware of signs and symptoms of heat exhaustion and heat stroke as well as treatment for each. chills, goose pimples, tingling arms, dizziness, weakness, fatigue, mental disorientation, nausea, and headaches are some symptoms that may signify the onset of heat illness, stop activity get to a cool place and consume some cool fluids (16) do not exercise if you have been ill or have had a fever within the last few days (17) check your medications, some medications such as antihistamines used to treat cold symptoms may block sweat production. drugs used to treat high blood pressure such as beta blockers and calcium channel blockers may impair skin blood flow and decrease heat loss from the body (18) if you plan to compete in a sport held under hot environmental conditions, you must become acclimatized to exercise in the heat

The following are prudent tips to prevent heat injury with exercise: 6-10

(6) hyperhydrate if you plan to perform prolonged, strenuous exercise in the heat. in general, drink about 16oz of fluid 30-60min prior to exercising (7) drink cold fluids periodically. for a long training run plan your route so that it passes some watering holes such as gas stations or other sources of water, take frequent water breaks consuming about 6-8oz of water every 15 min (8) replenish your water daily, keep a record of your body weight. for each pound you lose drink about 20-24oz of fluid, your body weight should be back to normal before your next workout (9) replenish lost electrolytes if you sweat excessively. put a little extra salt on your meals and eat foods high in potassium such as bananas and citrus fruits (10) avoid excessive intake of protein, as extra heat is produced in the body when protein is metabolized, this may contribute slightly towards heat stress

as the major electrolyte inside the body cells potassium works in close association with

sodium and chloride in the maintenance of body fluids and in the generation of electrical impulses in the nerves and the muscles including the heart muscle. potassium also plays an important role in the energy processes in the muscle. it helps in the transport of glucose into the muscle cells, the storage of glycogen and the production of high energy bounds

the major electrolytes in body fluids are

sodium, potassium, chloride, bicarbonate, sulfate, and calcium

four environmental factors interact to determine the heat stress imposed on an active individual: (3) air movement

still limits air carried away by convection. even a small breeze may help keep body temp near normal by moving heat away from the skin surface

shell temperature refers to

that which represents the temperature of the skin and the tissues directly under it, varies considerably depending on the surrounding environmental temperature

dehydration is?

the loss of body water which results in a state of hypohydration or low body water level

however, when the environmental temp rises, the evaporation of sweat becomes

the main means of controlling an excessive rise in the core temp. for example, evaporation of sweat may account for about 20% of total heat loss when exercising in an ambient temp of 50 degrees F (10 degrees C) but increases to about 45 % at 68 degrees F (20 degrees C) and 70% at 86 degrees F (30 degrees C)

several studies have reported that even during strenuous prolonged exercise with high levels of sweat losses, like marathon running for several hours water alone is

the recommended fluid replacement to help maintain electrolyte balance although added carbohydrate may provide some needed energy

rehydration has been shown to minimize

the rise in core temp to optimal race pace for a longer period. this beneficial effect is usually attributed to decreased dehydration and the maintenance of a better water balance in the blood and other fluid compartments. rehydration techniques both with water and with CES solutions have been shown to improve performance in exercise tasks of 1 hr or more in the heat

blood pressure readings are given in two numbers. the higher number (eg 120 mmHg) represents...

the systolic phase when the heart is pumping blood through the arteries. the lower number (eg. 80 mmHg) represents the diastolic phase when the heart is resting between beats and blood is flowing back into it. a measurement of <120mmHg systolic and <80mmHg diastolic is considered normal

Recent research suggests there is no gender difference for heat tolerance during exercise even though males and females differ in _____.

thermoregulatory response

osmoreceptors and other mechanisms also may stimulate the sensation of

thirst which is usually a good guide to body water needs and is effective in restoring body water to normal on a day to day basis. some sport scientists contend that thirst may also be a good guide to hydration status during exercise

in contrast if heat loss is insufficient to offset heat production is known as

uncompensated heat stress where the body temp continues to rise and exhaustion eventually occurs

a number of factors may influence the gastric empty rate including

volume, solute or caloric density, osmolarity, drink temperature, exercise intensity, mode of exercise and dehydration

sweat is mostly?

water (about 99%) but a number of major electrolytes and other nutrients may be found in varying amounts. sweat is hypotonic in comparison to the fluids in the body, this means that the concentration of electrolytes is lower in sweat than in the body fluids

an optimal amount of carbohydrate in solution may maintain body temp as effectively as

water and may enhance performance during prolonged exercise. water and carbohydrate complement each other to improve physical performance

therefore, carbohydrate intake may be useful to improve performance during such exercise tasks, but if temperature regulation is of prime importance then

water replacement should receive top priority. hence one of the goals of researchers has been to develop a fluid that will help replace carbohydrate during exercise in the heat without affecting water absorption

three main ingredients in sports drinks are

water, carbohydrates of various sources and concentrations and electrolytes. endurance athletes and individuals who are engaged in prolonged (over 1 hr) activity, especially in a hot, humid environment will derive the greatest benefit from CES consumption

the major concern is performance in prolonged exercise and

whether or not the core body temp is maintained

before competition and practice: (3)

if no urine is produced or urine is dark or highly concentrated, drink 3-5ml/kg body weight about 2 hrs prior to exercise. your urine should be clear, pale yellow before competition or practice

Research suggests that glycerol supplementation may _____.

increase blood volume enhance hyperhydration

the hypothalamus is usually very effective for

controlling body temp. however, certain conditions may threaten temp control. for example, an individual who falls into cold water will loose body heat rapidly for water is an excellent conductor for heat

A male body needs approximately how many cups of water?

13

The Adequate Intake (AI) value for sodium for men and women ages 9-50 years:

1500mg

The amount of sodium needed per day to maintain physiological function:

200mg

The Tolerable Upper Intake Level (UL) for sodium per day:

2300mg

The amount of sodium the Percent Daily Value (%DV) is based on:

2400mg

daily AI values for water intake have been established as

3.7l and 2.7l (3.9 and 2.9 quarts) for average males and females respectively based on 2005-2010 national health and nutrition examination survey (NHANES) data

although variable, the maximal evaporation rate is at about

30ml of sweat/min or 1.8l/hr. However, greater sweat rates may occur when sweat drops off the skin without vaporizing. only sweat that evaporates has the cooling effect

one liter of sweat if perfectly evaporated will dissipate about

580kcal of heat, in the previous example, the evaporation of 1.24l of sweat (720/580) would prevent a dangerous rise in the core temp. however, the evaporation of sweat from the body is not perfect as sweat can drip off the body and not carry away body heat so more than 1.24l may be lost

Our bodies are made up of approximately how much water?

60%

Every day, a female body needs about how many cups of water?

9

Lino has a strong family history of cardiovascular disease and he is worried about his father, who is quite unhealthy. Lino's paternal grandfather (his dad's dad) had high blood pressure and died of a stroke, and Lino's own father has atherosclerosis. His dad is a smoker who doesn't do any exercise and he is also very thin. Which of the following are risk factors for hypertension? Check all that apply.

A family history of hypertension is a risk factor. Atherosclerosis can raise blood pressure. Overweight people have six times greater risk of having hypertension than lean people. Smoking makes cardiovascular disease more likely.

_____ may lead to the best performance outcome when participating in prolonged exercise under warm environmental conditions.

A mixed-carbohydrate solution

there are at least two reasons why pre-cooling may be an effective ergogenic strategy for some athletes competing in heat. Sawka and young indicated that

cooling the skin will decrease skin blood flow so theoretically more blood could be shuttled to the muscles during exercise. according to Quod and others, an increased heat storage capacity will allow an athlete to complete a greater amount of work before reaching a critical body temp

body temperature refers to the internal or

core temperature

Why is it important to differentiate between hyponatremia and other heat-related injuries?

Because symptoms for hyponatremia may be similar to those for other heat-related injuries Because one would not want to offer excessive amounts of water to an individual with hyponatremia

Which of the following lifestyle modifications may help reduce blood pressure? Select all that apply.

Choose fresh rather than processed foods. Lose excess body weight.

radiation

Energy that is radiated or transmitted in the form of rays or waves or particles.

Water and beverage intake play a vital role in achieving fluid balance and proper hydration. Check all of the statements that apply to water and beverage intake: Check all that apply.

Fluids should not provide a significant amount of the energy or nutrients in a healthy diet; they should provide less than 10% of total calories consumed for a 2,200 kcal diet. If you don't drink enough water, your body eventually lets you know by signaling thirst; your brain is communicating the need to drink. The fluid from caffeinated beverages increases urine output; however, the fluid consumed from these beverages is not completely lost in urine, so these fluids still help to meet water needs. Alcohol inhibits the action of antidiuretic hormone; one reason people feel so weak the day after heavy drinking is that they are dehydrated.

evaporation

Liquid to gas

Which of the following statements about the safety of water is true?

Some bottled water actually comes from a municipal tap water supply

conduction

The direct transfer of heat from one substance to another substance that it is touching.

convection

The transfer of heat by the movement of a fluid

sawka and young noted that with compensated heat stress there is

a balance between heat production and heat loss. as a result a set body temp is maintained and the individual can continue to exercise

the american college of sports medicine in its position stand on exercise and hypertension stated that exercise is the cornerstone therapy for the primary prevention, treatment and control of hypertension. these are some of the major points of the position stand: (2)

a higher level of physical activity and fitness resulting from long term exercise training has a protective effect against hypertension; fitter people with hypertension will have lower blood pressure than those who are less fit even a single session (acute) exercise bout provides an immediate reduction in blood pressure which can last for a major portion of the day. this phenomenon which is discussed in recent view by Halliwell and others is known as postexercise hypertension. promoting the benefits of lowering blood pressure through single bouts of exercise may help motivate people to exercise. in a review comparing 27 acute aerobic and 5 acute resistance exercise studies Anunciaco and polito reported that aerobic exercise elicited postexercise hypertension of greater magnitude and of longer duration

health benefits to drinking more water: chang and others reported

a significant association between hypohydration and obesity. some dieticians indicated that increased water intake may help one reduce excess fat in a weight control program by increasing the sensation of fullness and suppressing hunger

an electrolyte is defined as?

a substance that in solution conducts an electrical current, the solution itself may be referred to as electrolyte solution. Acids, bases and salts are common electrolytes- they usually dissociate into ions, particles carrying either a positive (cation) or negative (anion) electrical charge

the food and drug administration (FDA) regulates bottled water as stringently as the EPA regulates tap water. Artesian water is drawn from

a well that taps a confined aquifer. mineral water comes from a protected underground source and must contain > 225 parts per million in minerals from a geological underground source. spring water flows naturally from an underground source

a number of pre-disposing factors have been associated with heat injury including

age, gender, level of physical fitness, body composition, previous history of heat injury, and degree of acclimatization

more recently, glycerol supplementation has been studied in

attempts to enhance endurance performance in warm environments

before competition and practice: (1)

be adequately hydrated the day before the competition, minimize consumption of alcoholic beverages the night before the competition because that may lead to hypohydration

Factors that can increase one's risk of heat injury when exercising may include:

being a young child being obese being physically unfit

the gatorade sports science institute has presented a method to calculate the sweat during exercise. to do so, one must accurately measure

body weight before and after exercise, measure the amount of fluid consumed during exercise, and measure the amount of urine excreted if any during exercise

body weight loss may not always be a reliable marker of changes in hydration status, however, cheuvront and others note that

body weight loss adjusted for fluid intake and urine losses is primarily a function of sweat losses

four environmental factors interact to determine the heat stress imposed on an active individual: (1) air temp

caution should be advised when the air temp is 80 degrees F (27 degrees C) or above. however, if the relative humidity and solar radiation are high, lower air temps, even 70 degrees F may pose a risk of heat stress during exercise

electrolytes can act at the

cell membrane and generate an electrical current such as a nerve impulse, they can also function in other ways such as activating enzymes to control a variety of metabolic activities in the cell

environmental heat may affect exercise performance in various ways:

central neural fatigue caused by increased brain temp, cardiovascular strain caused by changes in blood circulation, muscle metabolism changes caused by increased muscle temp, dehydration caused by excessive sweat losses

______ ions are a component of the acid produced in the stomach and are also used in the regulation of body-water balance.

chloride

Benefits of heat acclimatization include:

decreased body salt loss an increase in total body water a slower and less rapid rise in core temperature

Hyponatremia

deficient sodium in the blood or condition of subnormal levels of sodium in the blood, also known as water intoxication it can occur at rest simply by consuming too much water. it can also occur following prolonged exercise in which case it may be known as exercise associated hyponartemia (EAH)

gene therapy is unlikely to be available in the near future, so individuals must manage current essential hypertension with diet and medication. a variety of drugs are available to treat hypertension, including

diuretics, beta blockers, angiotension-converting enzyme (ACE) inhibitors and calcium channel blockers. if your blood pressure is elevated you and your doctor need to take aggressive action, this is very important for athletic individuals. Oliveria and Lawless suggest that drugs are less likely to have adverse effects on exercise performance. for example, diuretics and beta blockers may impair aerobic endurance performance

before competition and practice: (4)

do not excessively overhydrate which may increase the risk of dilutional hyponatremia if fluids are aggressively replaced during and after exercise

before competition and practice: (2)

drink slowly about 5-7ml/kg (.08-.11 oz/lb) body weight at least 4 hrs prior to exercise. fluid palatability (temp, sodium, flavoring) will enhance fluid intake. peacock and others reported that CES ingestion significantly increased pleasure ratings, ingested volume, and plasma glucose concentrations compared to water. if the exercise task is to be prolonged, carbohydrate may be added. a concentration of 6-8% is advisable, but concentrations of 20% and higher have been used by some individuals without adverse effects. beverages with sodium (20-50 mEq/l) and/ or salty foods or snacks will help stimulate thirst and retain fluids

The total amount of heat produced in the body depends on the ______ of exercise.

duration intensity

the ACSM indicates that

early recognition and rapid cooling can reduce both the morbidity and mortality associated with exertional heat stroke. in their meta analysis of seven studies McDermott and others concluded that ice-water immersion is the most efficient treatment for exertional heat stroke

four environmental factors interact to determine the heat stress imposed on an active individual: (2) relative humidity

evaporation of sweat is the body's main cooling system during exercise. as the water content in the air increases, the relative humidity rises which impairs the ability of sweat on the skin to vaporize and cool the body. in subjects performing low intensity exercise under relative humidity conditions ranging from 40-85%. Moyen and others reported decreased sweat evaporation and heat loss with higher humidity. with humidity levels from 90-100% heat loss via evaporation nears zero. some note that caution should be used when the relative humidity exceeds 50-60% especially when accompanied by warmer temps

carbohydrate is the primary fuel for high intensity endurance exercise for a duration of an hour or longer. Logan-Sprenger and others report that

exercise in warm environmental conditions and the resulting cellular dehydration accelerates muscle glycogen use. glycogen depletion contributes to fatigue

the american college of sports medicine in its position stand on exercise and hypertension stated that exercise is the cornerstone therapy for the primary prevention, treatment and control of hypertension. these are some of the major points of the position stand: (1)

exercise programs that involve endurance activities such as walking, jogging, running or cycling coupled with resistance training, help to prevent the development of hypertension and to lower blood pressure in adults exercise should be done daily for 30 min or more at a moderate level

Dehydration is detected by osmoreceptors in the

hypothalamus

any athlete who exercises in a warm environment is susceptible to heat injury but the increasing popularity of road racing has generated concern for runners who are not prepared for strenuous exercise in the heat or who participate in races that are poorly organized in regard to preventing and treating heat injuries. marathons are popular events with some major races having tens of thousands of runners. even well organized events may

experience problems in providing for the needs of runners when the environmental heat stress becomes excessive such as during an unexpected heat wave in races that normally have cooler weather. the individual who exercises unwisely under conditions of environmental heat stress may experience one or several of a variety of heat injuries. three factors may contribute to these injuries: increased core temp, loss of body fluids, and loss of electrolytes. however, other factors may also be involved as Noakes noted that several of the heat illnesses such as muscle cramps, also occur during exercise in cold environment

sanders and others examined

fluid shifts in three 90 min cycle exercise bouts at 60% VO2 max while consuming no fluid, water (1.2 1) and 100mmol saline (40 mmol sodium) solutions (1.2 1). plasma volume was similarly maintained by water and saline, leading the authors to conclude that sodium replacement provides little benefit to athletes rehydrating approx 50% of lost volume during exercise

health benefits to drinking more water: theoretically increased water intake could

flush carcinogens from the urinary tract and colon

We obtain water in the diet from fluid sources and foods like

fruits and vegetables

the DASH diet emphasizes

fruits and vegetables, nuts, low fat dairy, fish and chicken instead of red meat, low-sugar and low refined carbohydrate foods and reduced saturated and total fats

Although _____ may lead to greater retention of total body water, research findings regarding benefits to exercise performance are inconsistent.

glycerol supplementation

Andrew has been training for a half marathon through the spring, but as summer approaches the temperatures are warming up. Recently, Andrew went for a run on his lunch break and began feeling weak and nauseous, eventually getting the chills toward the end of the run. Andrew is likely experiencing _____________ and should ______________.

heat exhaustion; rest in a cool environment and replace salt and fluids

The most prevalent temperature threat to athletes is generally _____, or increased body temperature that occurs with exercise in warm environments

hyperthermia

the most prevalent threat to the athletic individual is

hyperthermia or the increased body temp that occurs with exercise in a warm or hot environment

hypohydration may affect numerous physiological processes that may impair physical performance. in separate reviews sawka and others noted that

hypohydration may lead to decreases in both intracellular and extracellular fluid volumes (particularly blood volume) with associated decreases in stroke volume and cardiac output. hypohydration also reduces both skin blood flow and sweating rate which can increase body heat storage

repeated exposure to a high core body temp during exercise helps the body to

make the following important adjustments (training table) during acclimization ( the ability for the body to undergo physiological adaptations so the stress of the environment is less severe) during exercise

drewnoski and colleagues reported that large percentages of older (75+) adults and children age 4-13 fail to

meet recommended AI water intakes

Most carbohydrate-electrolyte solutions contain a combination of:

mono- or disaccharides sodium water

more water is found in ?

muscle and nonfat tissue than in fat tissue. so water content can vary from 40% in obese individuals to 70% in very lean individuals

however, electrolyte replacement particularly sodium may be

necessary for some athletes participating in very prolonged bouts of physical activity such as marathons, ultramarathons, iron man type triathlons, or tennis tournaments where one might play off and on all day

sodium is also critical for

nerve impulse transmission and muscle contraction it is also part of several compounds such as sodium bicarbonate that help maintain normal acid base balance and may be effective as a ergogenic aid

water is a ?

non energy yielding nutrient

Since certain blood pressure medications may have adverse health effects for athletes, _____.

nonpharmacological approaches should usually be considered as a first choice of treatment

the basal metabolic heat production is provided through

normal burning (oxidation) of three basic foodstuffs in the body-carbohydrate, fat and protein. a higher basal metabolic rate, infectious diseases, shivering and exercise are several factors that might increase heat production

normal body water level is called

normohydration or euhydration

In general, the use of salt tablets to replace lost electrolytes during exercise is _____.

not necessary

in general the use of salt tablets to replace lost electrolytes, primarily sodium is

not necessary, an adequate diet will replace on a daily basis electrolytes lost in sweat

health benefits to drinking more water: drewenoski and colleagues reported that

plain water accounts for only 30-37% of total dietary water of U.S. adults. coffee, tea and other beverages contributing to total water intake may also have a positive or negative effects on health

Maintenance of intracellular water volume depends primarily on intracellular

potassium and phosphate concentrations

Indicate whether each electrolyte is intracellular or extracellular and a positively charged ion or negatively charged ion.

potassium: intracellular positively charged sodium: extracellular positively charged phosphate: intracellular negatively charged chloride: extracellular negatively charged

major functions of sodium:

principle electrolyte in the extracellular fluids it primarily helps maintain normal body fluid balance and osmotic pressure, therefore it is essential in the control of normal blood pressure through its effect on blood volume

exercise increases the metabolic rate and

production of energy. under a normal mechanical efficiency ratio of 20-25%, the remaining 75-80% of energy released as heat

four environmental factors interact to determine the heat stress imposed on an active individual: (4) radiation

radiant heat from the sun may create an additional heat load

major functions of chloride: chloride ions work with sodium in the

regulation of body water balance and in the formation of electrical potentials across cell membranes. it is also a part of hydrochloric acid (HCl) in the stomach which is necessary for certain digestive processes and is involved in the transport of CO2 from tissues in exchange with bicarbonate across the red blood cell membrane-process known as the chloride shift

hyperhydration is?

represents a condition in which the body retains excess body fluids. normal kidneys function very effectively to eliminate excess water during hyperhydration and conserve water during hyohydration

in general treatment of heat syncope, heat cramps and heat exhaustion involves

resting (preferably lying down), cooling the body if overheated and drinking fluids, preferably with sodium. most recover relatively quickly but should still be monitored

_____ is the primary positive ion in the extracellular fluid and plays a role in both nerve impulse transmission and acid-base balance.

sodium

the major electrolytes found in sweat are

sodium and chloride as sweat is derived from extracellular fluids such as the plasma and intracellular fluids which are high in these electrolytes

Extracellular water volume depends primarily on the extracellular

sodium and chloride concentrations.