Carbohydrate and exercise

Question 1

CHO-electrolyte duirng exercise

Answer 1

performance benefit
over 1 min faster
2% improvement

Question 2

Fast carbs

Answer 2

glucose
maltose
sucrose
starch-rich amylopectin

Question 3

Slow carbs

Answer 3

fructose alone
galactose
isomaltulose
amylose

Question 4

Guidelines during exercise

Answer 4

1.0g/min

1l/h sports drink
2 gels/h

Question 5

Mixture of carbs

Answer 5

oxidise higher rates
perform better

Question 6

Multiple transport carbohydrates

Answer 6

refers to sugars that are transported across the intestine by stimulating more than one protein transporter
glucose via SGLT1 and fructose via GLUT5

increase exogenous carb oxidation by 20-50%
improve gut comfort
prolonged, intense exercise = further performance enhancements

Question 7

Performance with glucose+fructose

Answer 7

8% faster compared to just glucose
19% compared to placebo (water)

Question 8

Guidelines carbs

Answer 8

60-120 min = glucose, glucose polymers, sucrose, 30-60 g/h, forms of CHO that are rapidly oxidized
180min+ = multiple transportable carbs (glucose-fructose sources), 90 g/h

improve endurance capacity/performance
benefit motor skills

Question 9

Metabolic effects carb feeding

Answer 9

maintain plamsa glucose conc
sustain high rates of carb oxidation
spare liver glycogen
spare muscle glycogen

Question 10

Non-metabolic effects carb feeding

Answer 10

reduce motor unit recruitment and power output

glucose mouth rinse can improve performance

Question 11

Long term post-exercise

Answer 11

8-24 hours
adoption of general daily CHO intake should ensure repletion on day-to-day basis

Question 12

Short term post-exercise

Answer 12

0-8 hours
more specific strategies may help to ensure rapid glycogen repletion

delayed carb feeding
measure rate glycogen synthesis

Question 13

Glycogen resynthesis phases

Answer 13

rapid phase
slow phase

Question 14

Rapid phase

Answer 14

1-2 hours free of insulin
insulin independent

Question 15

Slow phase

Answer 15

insulin dependent

Question 16

Regulation muscle glycogen synthesis

Answer 16

pancrease release insulin
bind with GLUT4 cell receptors on cell membrane
upregulation of glycogen synthase
after 1-2 hour driven by insulin = slower but last longer

Question 17

Glycogen synthesis

Answer 17

4-6 hours post exercise dependent on carb intake
above 1.2 g/kg bw/h = little or no further benefit

carb-rich food with mod-to-high glycaemic index = available soure of substrate for glycogen synthesis
important when max glycogen storage required after exercise

Question 18

Refulling after exercise

Answer 18

early/frequent feeding (first hour, 30 min interval for 4 hours)
1.2 g/kg CHO/h
protein if carb intake sub-optimal

Question 19

Post-exercise fructose-glucose

Answer 19

glucose = 6h synthesis rate - 3.7 +/ 0.5 g/h - 4h = 44 +/ 8 mmol/kg dm/h

fructose glucose = 6h synthesis rate - 8.1 +/ 0.6 g/h - 4h 39 +/ 8 mmol/kg dm/h

Question 20

Replenishment glycogen stores

Answer 20

accelerated when fructose co-ingested alongside glucose-based carbs
fructose co-ingested with glucose in recovery = enhance time to fatigue

Question 21

Main limitation to exogenous oxidation single carb

Answer 21

intestinal carbohydrate absorption

Question 22

Mechanisms exogenous carb oxidation

Answer 22

stimulate multiple transport carbs
sugars transported across small intestine by stimulating more than one protein transporter
SLGT 1 = glucose
GLUT5 = fructose
increase amount of carbs absorbed into circulation and delivered to the muscle

Question 23

SLGT1

Answer 23

glucose

Question 24

GLUT5

Answer 24

fructose

Question 25

Effect carb feeding during exercise on liver glucose metabolism

Answer 25

spare liver glycogen
supresses liver glucose output

Question 26

Limitation exogenous carb oxidation multiple transport carbs

Answer 26

saturation of SLGT 1 transporters

Question 27

Addition protein to post-exercise carb intake

Answer 27

increase muscle glycogen resynthesis
extra protein stimulates insulin secretion when carb intake is suboptimal