Summary
Phosphocreatine, glycolysis and oxidative metabolism supply ATP at different timescales of exercise.
In depth
ATP stores last seconds; phosphocreatine supports about 10 seconds of maximal effort; glycolysis for about 1 to 2 minutes; oxidative metabolism for prolonged activity. Fast-twitch fibres rely on glycolysis, slow-twitch on oxidation (rich in mitochondria and myoglobin).
Energy systems overlap and contribute in proportion to intensity and duration. Creatine supplements increase phosphocreatine stores. Training shifts reliance.
Remember: there is no on-off switch between energy systems.
Muscle contraction needs ATP, but the store lasts only 2 to 3 seconds of maximal effort. Energy is replenished by three systems on different timescales: phosphocreatine (creatine kinase transfers a phosphate to ADP) for the first 10 seconds; anaerobic glycolysis, which makes ATP quickly for up to 1 to 2 minutes, producing lactate; and oxidative metabolism, which has high yield and supports long activity using carbohydrate and fat.
Fibre types differ: slow-twitch (type I) are oxidative, rich in mitochondria and myoglobin and fatigue-resistant; fast-twitch (type IIx) are glycolytic and powerful but tire quickly. Training shifts the balance.
Example: sprinters have more fast fibres, marathoners more slow.
Remember: all systems work together, with proportions changing.
Frequently asked questions
What is Bioenergetics of Muscle?
Phosphocreatine, glycolysis and oxidative metabolism supply ATP at different timescales of exercise.
Which area of biology covers Bioenergetics of Muscle, and how advanced is it?
Bioenergetics of Muscle is one of the 53 topics in Metabolism & Bioenergetics. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Cori Cycle, Gluconeogenesis, ATP.
Can you give an example of Bioenergetics of Muscle?
Marathon runners have more slow-twitch fibres.
What should I learn before Bioenergetics of Muscle?
Work through the Beginner topics in Metabolism & Bioenergetics first, such as Metabolism, Anabolism and Catabolism, ATP, then return to Bioenergetics of Muscle. Advanced topics assume the Intermediate vocabulary.
What topics are related to Bioenergetics of Muscle?
The closest topics to Bioenergetics of Muscle are Cori Cycle, Gluconeogenesis, ATP, Anabolism and Catabolism. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Bioenergetics of Muscle?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Bioenergetics of Muscle. To practise the whole of Metabolism & Bioenergetics, use the Metabolism & Bioenergetics quiz.
How is Bioenergetics of Muscle different from Cori Cycle?
Bioenergetics of Muscle: Phosphocreatine, glycolysis and oxidative metabolism supply ATP at different timescales of exercise. Cori Cycle: Lactate from muscle is converted to glucose in the liver and returned, costing net ATP. Read both side by side and note what each one explains.
How should I study Bioenergetics of Muscle step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Cori Cycle and explain the difference aloud. Finally, take the Metabolism & Bioenergetics quiz and come back to this page for any question you miss.