Brainlag PlusAnaerobic respiration in muscles and fatigue, reading lactic acid and oxygen uptake graphs, the oxygen debt and the liver (Higher), trained and untrained athletes, and glycogen data for metabolism.
When oxygen runs short
During hard exercise the heart rate and breathing rate rise, but oxygen still cannot reach the muscles fast enough.
The muscles also respire anaerobically.
In muscle cells: glucose → lactic acid
The incomplete oxidation of glucose releases much less energy than aerobic respiration, and lactic acid builds up. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
- Clothes peg squeezes: 72 in minute 1, 44 in minute 5
- Fall = 72 − 44 = 28
- 28 ÷ 72 × 100 = 38.9% decrease (3 s.f.)
The rest of this lesson and its 12 practice questions are in Plus.
Screen 1 of 5, free to read.
- 12 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards