Last Updated29 February 2024

This chapter provides background information on the biomechanics most relevant to skiing. It outlines how the muscles and skeleton function as a system to create the movements of skiing by: describing the planes of movement and how these apply to skiing; describing the key bones, joints and muscles used in skiing; and describing how the body moves as this applies to skiing.

Anatomy of the Body

Biomechanics is the science of human bodies in motion. It combines the fields of mechanics (the physics of forces on objects in motion) and anatomy (muscles, bones and joints).

Skiing effectively requires blending the anatomy of the body with ski design and the forces of skiing (gravity, friction, and centripetal force).

Balanced movement – which is a combination of the rigidity of the skeletal system and tension in the muscles – will enable a skier to perform efficiently. This requires an effective athletic stance which involves using a blend of skeletal and muscular strength that promotes the ability to move in any direction.

How the body moves in a given skiing situation to ski effectively varies in each situation to achieve the desired outcome.

Proprioception

This involves developing the awareness of movement and the orientation in space of the body and its various parts, through internal sensors called proprioceptors. These are located primarily in the joints, muscles, tendons and the inner ear.

These proprioceptors are responsible for kinesthetic awareness. Developing a skier’s kinesthetic awareness is key to developing their ability to move accurately in order to achieve the desired outcome.

Example

To achieve an effective straight run the skier maintains a constant athletic stance, the skeleton and the muscular tension in the body are arranged effectively to achieve the outcome of a balanced straight run. Kinesthetic awareness of any adjustment needed to maintain centred balance will facilitate the ability to make those adjustments to achieve the desired outcome.

In a dynamic medium radius turn the muscular tension in the body is more dominant in the outside leg from initiation through to second half of the control phase. Use of the skeletal structure works with the muscular tension to resist against the forces of the turn.

Strong muscular tension throughout the body is required to maintain a centred athletic stance.

Precise use of vertical movement in the legs and hip joint is required to increase and decrease muscular tension to achieve the outcome of increasing and decreasing pressuring/bending of the skis.

Kinesthetic awareness of the body relative to all four movements and the anatomical planes, gives the skier the information to respond and achieve the desired outcome of dynamic skiing.

Anatomical Body Planes

For the purposes of most biomechanical descriptions the movement of the body is broken into three imaginary planes or direction of movement: sagittal, frontal and axial. The NZSIA uses four directions of movement to describe skiing. Fore/aft, rotational, lateral and vertical movements all exist within the three anatomical planes of movement described below.

The anatomical body planes dissect the body vertically and horizontally and intersect at the centre of gravity.

Sagittal Plane

A vertical plane that runs through the body from front to back or back to front. This plane divides the body into right and left halves. Fore/aft and vertical movements occur within this plane.

Flexing the ankles to move forward along the length of the skis or extending the ankles to move backward along the length of the skis are examples of fore/aft movement in the sagittal plane and also examples of vertical movement (flexion and extension).

Frontal Plane

A vertical plane that runs through the centre of the body from side to side. This plane divides the body into front and back halves. Lateral movement occurs within this plane.

For example, lateral movement of the femurs to increase or decrease edge angle of the skis, and angulation of the upper body occur in the frontal plan.

Axial or Rotational Plane

A horizontal plane that runs through the midsection of the body. This plane divides the body or parts of the body into upper and lower halves. Rotational movement occurs within this plane.

Turning the legs underneath a stable upper body or rotating 360 degrees off a jump are examples of rotational movements in the horizontal plane.

Body Components

The body can be broken down into its component parts. The component parts, while separate structures, work together to produce movement.

Bones are the underlying rigid structures that form the skeleton, this is the framework supporting the body. The skeleton protects vital organs and provides attachment points for muscles and connective tissues. When the bones of a skier’s skeleton are aligned to withstand skiing forces, muscular effort is less strenuous.

Joints are the juncture where two bones meet. Some bones can move in one plane of movement while others can move in all three.

Muscles are bands of soft tissue fibres that contract and relax to stabilise or move joints.

Each individual person has a different anatomical make up. Individual skiers’ bone structure, joint movement, muscular strength and connective tissue all affect how they perform.