5 Introduction to the Physics of Ski and Snowboard Positioning
Center of Gravity (Mass)
The center of gravity (or center of mass) is the three dimensional balance point of an object. In the human body it is located just above the pelvis. Due to anatomical differences in the shape of the pelvis, the center of gravity is slightly higher in biological males than biological females. However, body type and height play a more significant role than gender.
Our center of gravity changes depending on what position we are in. For example, if you bend forward at the hips, the center of gravity moves forward. In skiing, a skier moves their center of gravity through a skill called angulation. By angulating and moving your center of gravity, you can move or maintain your balance point. This is how a skier determines how much weight to assign to the inside or outside, or the front or back of their skis.
On average, approximately 65% of a person’s mass is contained in the upper body and approximately 35% in the lower body. As a result, small movements of the upper body have a disproportionately large effect on a skier’s balance and the distribution of force and pressure on the skis. To maintain balance it is important to keep the upper body quiet when skiing and to position the torso over the part of the ski you want to apply force to.
Attribution: Glynda Rees Doyle and Jodie Anita McCutcheon, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons
Base of Support
The Base of Support refers to the area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface. When we are standing without skis on, our base of support is the bottom of our feet. In a skier, the base of support is the base of the skis and the area between where they contact the snow. When you plant your pole this expands your base of support. We need to coordinate movements with all our different body parts so that our base of support directs our center of mass.
References
LeMaster, R. (2010). Ultimate Skiing. Human Kinetics.
