Resistance of gravity in skating (roller or ice)

For a skater, the gravity affects the speed with a negative effect for ascent or positive for descent. On a flat way, gravity is not negligible or zero unlike other sports (cycling for example).

Newton's law

The Newton's law determines the role of the hearth attraction. The gravity resistance **Rg** depends on the slope **Pt** (slope calculation) and the total weight, i.e. the total mass **Mt** (skater plus equipment) and the acceleration of gravity **g**. Obviously, this resistance is zero on a flat way.

Style

The gesture to move forward with skates consists of alternated and repeated thrusts. It introduces a vertical oscillating movement of the gravity center of the skater's body. The associated resistance **Rs** depends (as above) on the total weight and eventual slope. According to the skating style, it is possible to evaluate the resistance with a coefficient **Cs**.

We can consider:Cs = 0.010 for "irregular" skating (novice, sprint, etc.)Cs = 0.008 for "dynamic" skatingCs = 0.006 for "fluid" skatingCs = 0.004 for "economic" skating |

**N.B.** Cs represents only the gesture cost for gravity and should not be confused with the global gesture efficiency.

Calculation formula

In summary, the mathematic formula allowing calculation is:

**Rg = Mt g Sin(Arctan(Pt))**

**Rs = Mt g Cs Cos(Arctan(Pt))**

Calculation of the skating power

J.L