exercise and GI function

Question 1

ingested fluid availability is dependant on which two factors

Answer 1

gastric emptying

intestinal absorption

Question 2

which factors affect gastric emptying

Answer 2

gastric volume
energy density
osmolality
exercise intensity

Question 3

what is the site at which most fluid and macronutrient absorption takes place

Answer 3

small intestine

Question 4

what is the function of the microvilli

Answer 4

increase surface area for absorption

Question 5

what factors affect intestinal absorption

Answer 5

%CHO
type of CHO
Na+ (glucose - sodium co transporters - SGLT1
osmolality

Question 6

what determines optimum fluid intake

Answer 6

combination of ambient temp (sweat loss) and exercise intensity determine how much fluid and carbohydrate is necessary

Question 7

how does a high cho concentration affect absorption of fluid

Answer 7

reduce absorption of fluid and hence fluid availability
high cho concentration leads to high osmolarity which causes net movement of water into intestinal lumen
this leads to a net loss of water and has a dehydration effect

Question 8

how much fluid should be ingested before exercise to prevent hypohydration

Answer 8

4-600ml of fluid

Question 9

what should cho content in fluid be during exercise?

Answer 9

high enough to provide substrate but not so high that osmolality becomes too high and water absorption is impeded

Question 10

what are the hazards of exercise for GI tract

Answer 10

nausea, heart burn, diarrhoea, Gi bleeding, mechanical injury of organs

Question 11

what are the long term risks of GI bleeding

Answer 11

Fe deficiency and anaemia

Question 12

how can GI bleeding be avoided

Answer 12

avoidance of NSAIDS and dietary fluid intake

Question 13

exercise may reduce the risk of which GI tract diseases

Answer 13

GI cancers, gallstones, GI haemorrage, inflammatory BD and constipation

Question 14

how is exercise thought to reduce the risk of colon cancer

Answer 14

reducing intestinal transit time, thus lowering secondary bile acids and increasing faecal short chain fatty acids
also improve immune function, decrease bmi, decrease insulin resistance

Question 15

how does exercise reduce the risk of gall stones

Answer 15

exercise linked to decreased weight and better diet
exercise acts against glucose tolerance, high serum insulin, TGs, low serum HDL to prevent gall stones
also regulates CCK

Question 16

how does exercise affect the risk of IBD

Answer 16

IBD - not IBS!!!!!
ulcerative colitis and crohns disease
sedentary groups have higher incidence of IBD
patients with IBD take steriod drugs to help with symptoms but this causes muscle weakness and osteoporosis
exercise helps to reduce the effect of the steroids and hence can increase quality of life for these patients

Question 17

how does exercise affect constipation

Answer 17

increased gut motility, decreased blood flow to gut

biomechanical bouncing of the gut and increased fibre intake as a result of increased EE

Question 18

how does repeated high intensity exercise affect gut function

Answer 18

intense exercise 70%+ VO2 max - during exercise blood flow is diverted to heart and working muscles and away from digestive system - during intense exercise more blood is diverted away, almost 60-70% decrease in blood flow - resulting in temporary ischemia of the gut
long term repeated high intensity exercise can lead to tissue damage due to ischemia

Question 19

what neuro/immuno/endocrine changed are caused by exercise

Answer 19

hormone levels change - CCK, secretin, noradrenaline, adrenaline, glucagon
boots immune function via various cells - macrophages, neutrophils, natural killer cells
severe exercise may possible reduce natural killer cells + increase free radicals but exercise increases production of antioxidants

Question 20

why is glucose present in sports drinks

Answer 20

activation of the SGLT1 glucose-sodium transporters - increased intake of glucose and sodium
water follows salt