The gut during exercise

运动中的肠 · 血流被抢走之后

Place · Level 3 · Movement

Connected to · 3

synergy · 1

Water & Electrolytes
When plasma volume falls, the splanchnic bed is clamped; intensity itself also moves cardiac output off the gut toward muscle and skin. The two lines can stack. They are not the same line.

regulates · 1

Digestive
SGLT1 on the small-intestine apical membrane pulls glucose in with sodium at rest; during exercise that door saturates, and fructose uses GLUT5 instead. Same door, different load.

contrast · 1

Glycogen supercompensation
Glycogen supercompensation is synthase inside the muscle still on after emptying; the gut during exercise is blood flow, the stomach, and two sugar doors before that sugar has entered the muscle. Do not merge them into 'just eat more carbohydrate'.

血先给肌肉和皮肤

Stop 1/4

Blood goes to muscle and skin

The heart can send out only so much blood in a minute. Once you run, working muscle wants blood, and heat sends blood to the skin to dump heat. Those two flows together are more than the resting gut ever received.

The body does not shave a little off every organ. It clamps by priority. The splanchnic bed — stomach, small intestine, liver, spleen — is turned down first. van Wijck 2012 writes this as splanchnic hypoperfusion during exercise: the gut wall gets less oxygen and less substrate, the barrier gets brittle, and the person feels sick, crampy, ready to vomit.

That late-race wave of nausea is often this tissue having its blood stolen, not lunch gone bad. The water-and-electrolytes island already marked the line where plasma volume itself is falling. This island is the prior step: intensity alone, before thirst, already moves blood off the gut.

Read story

Educational content, not medical advice — consult a clinician.

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The gut during exercise

运动中的肠 · 血流被抢走之后

Place · Level 3 · Movement

Connected to · 3

synergy · 1

Water & Electrolytes
When plasma volume falls, the splanchnic bed is clamped; intensity itself also moves cardiac output off the gut toward muscle and skin. The two lines can stack. They are not the same line.

regulates · 1

Digestive
SGLT1 on the small-intestine apical membrane pulls glucose in with sodium at rest; during exercise that door saturates, and fructose uses GLUT5 instead. Same door, different load.

contrast · 1

Glycogen supercompensation
Glycogen supercompensation is synthase inside the muscle still on after emptying; the gut during exercise is blood flow, the stomach, and two sugar doors before that sugar has entered the muscle. Do not merge them into 'just eat more carbohydrate'.

血先给肌肉和皮肤

Stop 1/4

Blood goes to muscle and skin

The heart can send out only so much blood in a minute. Once you run, working muscle wants blood, and heat sends blood to the skin to dump heat. Those two flows together are more than the resting gut ever received.

The body does not shave a little off every organ. It clamps by priority. The splanchnic bed — stomach, small intestine, liver, spleen — is turned down first. van Wijck 2012 writes this as splanchnic hypoperfusion during exercise: the gut wall gets less oxygen and less substrate, the barrier gets brittle, and the person feels sick, crampy, ready to vomit.

That late-race wave of nausea is often this tissue having its blood stolen, not lunch gone bad. The water-and-electrolytes island already marked the line where plasma volume itself is falling. This island is the prior step: intensity alone, before thirst, already moves blood off the gut.

Read story

Educational content, not medical advice — consult a clinician.