# Muscle power

Human and animal work, fuelled by food that plants made from sunlight.

Source page: https://www.materialinsights.org/energy/e_muscle/

Natural sources · Solar-derived flows · No. 10

- Natural sources
- Origin: Indirect solar
- Renewable: Yes
 Natural sources · Solar-derived flows · Foundation · Energy

A working adult sustains only about 75 watts, yet about two-thirds of the world's farmers still rely on hand tools.

Chart: Illustration: Muscle power

##### Where it comes from

Plants turn sunlight into food and fodder, and muscles turn that chemical energy into work: about 75 W for a working adult.

About 8.2 billion people and some 400 million draught animals supply it, with hand and animal labour most common in sub-Saharan Africa.

##### Three things to know

1. A horse can sustain about 750 W for a few hours, against about 75 W for a person.
2. Only about 30 million of the world's farmers use machines; most of the rest work with hand tools.
3. In sub-Saharan Africa in the late 1990s, 65% of cultivated land was prepared by hand and only 10% by tractor.

##### The journey

1. 1 **Sunlight**Grows crops, grass and fodder
2. 2 **Food**Eaten by people and working animals
3. 3 **Muscles**At best a quarter becomes work
4. 4 **Work**Ploughing, carrying, pedalling and lifting
 Covered in [Earth's energy flows: sun, wind, water, heat and lifeEnergy](https://www.materialinsights.org/learn/energy/earths-energy-flows/)[Muscles, wood, water and wind: energy before fossil fuelsEnergy](https://www.materialinsights.org/learn/energy/energy-before-fossil-fuels/)

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_muscle/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_muscle/correlation/index.md)
- [How energy resides](https://www.materialinsights.org/energy/e_muscle/resides/index.md)
- [Abundance](https://www.materialinsights.org/energy/e_muscle/abundance/index.md)
- [Fluctuation in time](https://www.materialinsights.org/energy/e_muscle/time/index.md)
- [Across the Earth](https://www.materialinsights.org/energy/e_muscle/geography/index.md)
- [Impact on nature](https://www.materialinsights.org/energy/e_muscle/nature/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_muscle/links/index.md)