A speed skater skillfully manipulates the skate blade 40cm long and 0.9mm thick on the ice polished like a mirror. With the speed of 60km per hour the skater aims at the victory.
Let's see here what technique is used to reach such high speed and how much load is applied to the skater's leg.
The lower figure showes what kind of force is applied to the skater while he is skating at a high speed. Air resistance and the frictional resistance of the ice are acting on the skater. The friction depends on the condition of the ice and the skate edge. Before the game the ice is swept by the conditioning machine and the skate edge is polished and sharpened by the skater himself.
Air resistance is like wind pressure which you feel thrusting your hand out of the car window. To minimize the air resistance, skater flexes the upper body forward, and makes a low posture.
The picture below shows the skater running straight and the trail of skate edge on the ice. The skate trail shown in blue line is S-curve although the skater is running straight. The S-curve is produced by the skater tilting the skate outward and inward.
You may have the same experience when you ride a bike. Tilting the bike right or left, you can change the direction of the bike without turning the handle bar. Good skater skillfully tilts the skate and makes S-curve movement which helps the skater to move forward.
The picture below shows the force working on the skater during the curve skating. Curve skating is different from straight running because of the centrifugal force which pulls the skater outward. The centrifugal force often makes the skater fall down.
The faster the skater runs and the smaller the diameter is, the greater the centrifugal force is. To compensate the centrifugal force the skater leans the body inside. Skater's leg must support 1.5 times body weight at this moment.
