Unit 4 Nutrition

water

considered the most important nutrient

how much of the adult body is water

60%

what are some functions of water?

Water provides the aqueous medium for chemical reactions and other processes within cells, transports substances throughout the body, facilitates thermoregulation (maintenance of body temperature), and is critical to most other physiological processes

do athletes need individualized plans for fluid/electrolyte intake?

yes, it is important to know how much to have before, during, and after exercise

plan will need to be adjusted to reflect changing environmental conditions

what 2 major aspects need to be considered with fluid balance

1. water volume

2. the concentration of solutes in body fluid

euhydration

adequate water to physiological demands

hyperhydration

excess water; considered temporary

hypohydration

insufficient water volume

dehydration

process of the body losing water colume

fluid balance

considers water volume and solute concentration

what electrolytes are involved in fluid balance

• Sodium Na+

• Potassium K+

• Calcium Ca2+

• Magnesium Mg2+

• Chloride Cl-

• Bicarbonate HCO3-

• Phosphate PO4 3-

• Protein

osmosis

Water movement through a semipermeable membrane from an area of lesser solute concentration to an area of greater solute concentration so the concentrations will equalize.

hypotonic

having lower osmotic pressure than another fluid

hypertonic

having higher osmotic pressure than another fluid

what factors can change the amount of water in the body?

• body size

• gender

• age

• body composition

what relationship does body water % and age and body fatness have?

an inverse relationship; it declines with advancing age and increasing body fatness

does fat contain a lot of water?

no; lipids are anhydrous

contains around 10% water

how does water move?

moves from an area of lower solute concentration to an area of higher solute concentration

insensible water loss

typically not noticeable

ex: water lost through ventilation and through nonsweat diffusion through the skin

sensible water loss

can sense it

ex: fluid lost in feces, urine, and sweat

how much urine is produced in an average person?

around 1500mL per day

Diuretic effect

causing an increased output of urine

ex: alcohol

what about caffeine?

increases urine output by increasing the blood flow in the kidneys and increasing sodium and chloride excretion

Adults in the US consume BLANK percent of their total daily water intake via food and BLANK percent from tap or bottled water

20-25, 30-35

what is another source of water?

a result of aerobic metabolism, contributes to around 350 mL

what are predominant substances in sports drinks and fruit juice

sugars; sports has glucose and fruit has sucrose

should you take substances that have electrolytes?

would be preferred if you can get it from food, if someone can’t absorb it well, then supplements would be recommended

sodium plays a vital role in maintaining fluid balance, does this mean that athletes should consume a high-sodium diet every day?

if someone exercises more, they need more calories, so they would get the sodium through this, if they sweat more or are in a hot environment then they can consider consuming more

what factors affect sweat rate

• exercise intensity

• environmental conditions such as temp. and humidity

• clothing

• training status-trained start sweating sooner

what is advantage of trained athletes of sweating sooner

this can help regulate their body temp faster

why might people sweat more in colder temps?

because the air is dry and the body must add more water vapor to cold air

amount of sweat loss during exercise

• sweat loss varies considerably

• around 100mL daily in nonexercise, temperate conditions

• 1-2L/hr if exercising in high temps with protective clothing

• over 2.5L/hr in prolonged exercise in the heast

hypoatremia

low sodium levels in the blood usually caused by excess water retention relative to sodium

hypovolemia

less than normal extracellular fluid (blood) volume

this can affect blood flow and thus oxygen delivery

hyperthermia

high body temperature, which can lead to coma or death

the more loss of body water, the greater the increase in body temperature

what results in hypohydration

• heat dissipation ability is impaired, so higher body temps

• a decrease in whole-body sweating

• decrease in skin blood flow and blood volume

effecrs of dehydration on aerobic performance

• movement slows

• attention declines

• power output decreases

• for runners, the running time may increase

EAMC

exercise associated muscle cramping

what is a belief of EAMC

that it may be due to altered neuromuscular control, a result of the repeated muscular contractions which can cause muscle fatigue

can also be associated with dehydration and electrolyte loss

what are heat related cramps caused by

affects the whole body and it is believed that it is from the rapid loss of fluid and sodium

does fluid loss result in performance loss?

Fluid losses of 2–7 percent of body weight will likely impair aerobic exercise performance, particularly in the heat. Losses of 1–2 percent of body weight may not impair performance, particularly if the exercise is less than 90 minutes in duration and in a temperate environment.

if heavy sweating occurs what should happen?

this results in sodium loss and it should be replaced if the activity duration is longer than 1-2 hours

how to get accurate measures of total body water?

• using isotope dilution, but it is expensive and time consuming

• measuring plasma solutes through blood sampling

• urine

regulation of urine volume

1. fluid intake is low

2. blood volume decreases and osmotic pressure increases

3. posterior pituitary secreates ADH

4. collecting ducts become more permeable

5. water reabsorption increases

6. blood volume increases and osmotic pressure decreases

7. ADH secretion is inhibited

how much kg is 1L of water

1kg or 2.2lbs

what 3 things should an athlete evalutate if they may be hypohydratred

1. they are thirsty in the morning

2. their urine id dark yellow

3. their BW is lower than the previous morning

hydration goals prior to training

• being fully hydrated prior to exercise

• if not, rehydrating to the greatest extent possible

• avoiding GI upset

• consuming carb, if appropriate

• must be individualized and guided by

  • anticipated intensity and duration of activity

  • potential effect of hypohydration on performance

  • environmental conditions

hydration goals during training and performance

• replacing lost body water to the extent possible

• slowing dehydration to the extent possible

• avoiding the overconsumption of water and other hypotonic fluids

• replacing sodium if losses are large or rapid

• consuming carbohydrate if appropriate

• avoiding GI upset

• customized to consider sweat rate, sweat composition, duration, clothing, and environmental conditions

hydration goals after training and performance

• restoring lost body water to achieve euhydration

• replacing sodium and other electrolytes lost

• consuming adequate carbohydrate to fully restore muscle glycogen

• consuming adequate protein to build and repair skeletal muscle

• avoiding GI upset

• approx. 1.25-1.5 L of fluid/kg of BW lost, as soon after exercise is practical

in which compartment is the largest amount of body fluid stored?

intracellular fluid

the primary cation in extracellular fluid is

sodium

having a normal or optimal amount of water in the body is termed

euhydration

which of the following electrolytes might be deficient in the diet of a person from an industrialized country?

potassium

what can wearing uniforms and protective gear while exercising in the heat do?

restrict the evaporation of sweat and results in body temp rising

a person exercsing in a hot and humid environment might lose how much fluid through sweating?

1-2L per hour

water only is an appropriate pre-exercise beverage for?

exercise lasting less than 60 minutes

2 factors that may be associated with hypoatremia include?

1. large losses of sodium in sweat

2. excessive water intake

vitamins

essential nutrients needed in small quantities for the proper functioning of the body

fat-soluble

• includes A,D,E,K

• stored in liver and adipose cells

• transport in blood requires carrier

• storage protects against deficiencies

water-soluble vitamins

• includes all B complex and C

• circulate easily in blood

• excess is excreted

• no designated storage sites

what happens with an excess of water soluble vitamins

some there is no toxicity, but for others symptoms may occur such as headaches

what are some other classifications of vitamins

• related to energy metabolism

• needed for RBC formation

• associated with antioxidant functions

• needed for growth and development