Week 3 - Fluid Balance, Exercise & Renal Disease Flashcards
On average, how much of female and male body mass is water?
- 55% females
- 60% males
How is water distributed throughout the body?
a) Intracellular volume
b) Extracellular volume
a) 2/3 ICF
b) 1/3 ECF
What are some functions of body water?
- Transport medium for most body nutrients and gases
- Moistens surfaces for nutrient transfer
- Medium for most waste elimination
- Lubricates joints (water and proteins)
- Give structure and form to most body structures (water is non-compressible)
- Provides cushioning for many body structures
- Body thermoregulation
How much of our water do we get from:
a) Fluids
b) Food
c) Metabolism
a) Fluids: 50-60%
b) Food: 30-40%
c) Metabolism: 10-15%
What does fluid in the body effect?
- Osmolarity
- Blood volume
- Arterial blood pressure
- Cardiac output
What are some roles of the renal system?
- Formation and excretion of urine
- Regulate blood volume and pressure
- Regulate mineral concentrations (Na, K, Ca, plasma ion)
- Stabilise blood pH
- Conserve nutrients - glucose and amino acids
- Excrete waste: urea, ammonium
- Detoxify poisons: drugs
What part of the brain regulates body fluid and electrolytes?
Hypothalamus
What are the inputs to hypothalamus regulating body fluids and electrolytes?
- Osmoreceptors
- Atrial baroreceptors
- Arterial baroreceptors
- Thrist
What are hormonal and modulator outputs regulating body fluids and electrolytes?
- Antidiuretic hormone (ADH) or vasopressin
- Aldosterone
- Angiotensis Converting Enzyme (ACE)
- Atrial Natiuretic Peptide (ANP)
Antidiuretic Hormone (ADH)
a) Where is it secreted from?
b) What 3 inputs does it respond to?
c) What effects on the body does its release have?
a) Cells in posterior pituitary
b) Osmoreceptors, baroreceptors, angiotensin II
c) Increased water reabsorption in kidneys = decreased urine output and increased extracellular volume, and increased arterial BP
Aldosterone
a) Where is it secreted from?
b) What is its release stimulated by?
c) What effects on the body does its release have?
a) Adrenal cortex
b) Low arterial BP and low renal blood flow
c) Increased Na reabsorption in kidneys, decreased Na loss in sweat, increase plasma volume
What effects does angiotensin II have on the body?
- Increased aldosterone release
- Increase ADH release
- Arteriolar vasoconstriction (increases BP)
- Increase thirst
How does angiotensin converting enzyme (ACE) work?
- Secreted by lungs, converts angiotensin I –> II
Atrial Natiuretic Peptide
a) Where is it secreted from?
b) What is its release stimulated by?
c) What effects on the body does its release have?
a) Atrial cells
b) Release primarily stimulated by atrial stretch
c) Increased diuresis, decreases arterial BP
What effects does exercise have on fluid and electrolyte balance?
- Increased sweating
- Increased osmotic pressure in cells due to metabolites
- Increased hydrostatic pressure due to increased BP
What are some acute physiological responses to exercise?
- Increase ADH release
- Increase renin, angiotensin II and aldosterone release
- Decrease ANP release
- Increased sodium reabsorption
- Increased water reabsorption
- Decreased urine output
- Increased plasma volume
What are some effects of repeated days of physical activity?
- Increase release of fluid balance hormones
- Increased plasma volume
- Possible haemodilution & pseudoanaemia
How could someone prevent dehydration with exercise?
- Ensure adequate hydration pre-exercise
- Weigh before and after exercise
- Ensure pale yellow urine
- Hydrate during exercise if long duration, high ambient temperature or humidity
- Have appropriate sports drink if required
- Be conscious of salt intake
What is hyponatraemia and what are some symptoms?
Hyponatraemia is low sodium levels, due to excess water intake relative to sodium
- Symptoms include headache, confusion, nausea, cramps, seizure, APO, death
Who is most at risk of hyponatraemia?
- Less accustomed to prolonged exercise
- Poorer physical condition
- Unacclimatised to heat and humidity
- Consume a low salt diet
- Take diuretic medications
- Sweat profusely
- Consume large quantities of plain water
What can someone do to prevent hyponatraemia?
- No more than 1L of pain water per hour during or after exercise
- Adding some sodium and glucose to drink
- Sprinkle salt on food in days prior to and following exposure
What are the two major causes of renal disease
- Diabetes: 45%
- Hypertension: 27%
What are the three patient groups under severe renal disease?
- Haemodialysis
- Peritoneal dialysis
- Renal transplant
What medications are people with CKD commonly on and how does this impact their exercise?
Predinosine - a corticosteroid which impairs maintenance or growth of muscle mass
What is the main physical fitness issue in people with CKD?
Very low aerobic capacities (VO2max)
What are some fitness tests that can be used for people with CKD?
- ADLs
- Stair climbing
- 6 minute walk test
What are aerobic testing considerations for people at:
a) Stages 1-4 of CKD
b) Renal transplant
c) Stage 5
d) Haemodialysis
e) Peritoneal dialysis
a) Stages 1-4 of CKD - usual considerations
b) Renal transplant - usual considerations
c) Stage 5 - medical supervision
d) Haemodialysis - test on non-dialysis days
e) Peritoneal dialysis - test when no fluid in abdomen
What are the strength test considerations for people with CKD?
- 3RM or more (not 1RM)
- Isokinetic - slower velocities
- Sit to stands
What are CV/aeorbic activity training recommendations for people with CKD?
- Low-moderate intensity activities (40-60% max)
- As many days as possible
- RPE 11-13, non-dialysis days RPE 11-16
- Begin with intermittent (interval) activity
- Progress to continual activity
- Aim for 30-45 minutes continuous, longer if overweight
What are strength activity training recommendations for people with CKD?
- Aim to increase or maintain muscle mass
- 1 set of 10-15 reps to fatigue
- 8-12 exercises targeting major muscle groups
- 2x week, non-consecutive days
- Motivation often difficult
What are exercise timing considerations for dialysis patients
a) pre-dialysis
b) post-dialysis
c) during dialysis
d) non-dialysis days
a) pre-dialysis - fluid load problems e.g. breathlessness
b) post-dialysis - fatigue, hypotension. Don’t train immediately post
c) during dialysis - possible during the first 2 hours of dialysis e.g. cycling, resistance training trial
d) non-dialysis days - exercise usually better tolerated
