Until I became familiar with and started writing about the PMTS, a ski boot appeared to be just that, a ski boot. But I soon learned that using the right boot, a lateral boot will alleviate stress on the knees, enhance your edge control and promote breakthroughs in your skiing. Since I first started writing about the differences between boots some years ago I've had many frustrated responses from readers who, in looking for a lateral boot, were left even more confused.

If you go into a ski shop and ask a boot technician for a lateral boot or what the difference is between the two, you may come up empty handed. The boot tech is not to be faulted because many simply don't know. Why all the confusion? Traditional ski teaching methods promote rotary movements to make a turn. Old school traditionalists have the ear of ski manufacturers who design ski boots to encourage rotary movements. Most of the boots found on shop racks or at the numerous ski sales tend to be rotary boots. Only recently have ski boot manufacturers have begun answer the demand and design ski boots that put a skier in a more neutral position with a lateral boot.

The terms rotary or lateral describe the movements a skier must make to bring the skis to the edge. A rotary boot promotes rotary movement (foot steering and knee rotation) while a lateral boot supports lateral, tipping or tilting movements to engage the skis in the turn. The difference between the two types of boots is demonstrated when you stand on your skis. The direction your knee moves when you make a turn is called "tracking". Rotary boots force the knee to move or "track " to the inside or big toe edge during a turn. When the knee tracks inside, it creates a skidding action that makes it impossible to put the skis on edge. The tail washes out and results in an "A" frame where the knees are touching and the feet are apart. The "A" frame can be seen distinctly at the middle or end of a turn as the downhill ski breaks away. This action will give less control of your feet and skis as the "A" frame will block the hips from moving inside the turn. It becomes even more pronounced if you intentionally try to move the downhill or outside ski to the big toe edge.

In the past this was the way skiing was taught. But now with the advent of shaped skis and efficient movements, lateral boots become the key to pronounced breakthroughs. A skier using a lateral boot stands in a neutral (or straighter stance as compared to a flexed) position over the foot. Lateral boots help the knee move or "track" straight ahead, or slightly outside, rather than inside to the big toe edge. Rather than twisting or steering your knees and feet as you do with a rotary boot, lateral movements of tipping or tilting the skis are all you need to engage the edge and bring the skis through the turn. It is impossible to create lateral movements with rotary boots.

Another factor is "lateral boot strength". This is measured in how the boot helps you hold an edge against the centrifugal forces of a turn. Every ski boot performs this function differently. The test of a boot is how well it holds once you put the ski on edge. The inner wall is high and stiff and supports the ankle and foot. It is this support that allows you to transfer energy for edging or carving to your skis. Once you begin to tip your ski on edge, the lateral strength will determine whether you can hold the edge, hence the name, lateral boot. Lateral boots also help with carving and increased edge control, especially on steep or icy conditions.

How can you tell the difference between a rotary or lateral boot? · Look at the position of the hinges or rivets on the upper cuff. (The rivets are directly alongside the ankle knuckles.) A lateral boot will feature the inside (medial) rivet as being equal to or higher than the outside (lateral) rivet. Rotary boots will have the inside rivet equal to or lower than the outside rivet. Check your "ramp angle" and forward lean. The ramp angle is the height or lift of your heel, measured in degrees on a plane from the ball of your foot to your heel. A high ramp angle puts you in a position similar to wearing a pair of high heels. The higher the ramp angle and the greater the forward lean of the upper cuff, the more rotary or skidding movements you will encounter when you try to put the ski on edge. Lateral boots have a lower "ramp angle" and less forward lean of the upper cuff. All that is needed to put the ski on edge with a lateral boot is a tipping or tilting of the skis. Lateral boots, combined with the right movements, can give greater edge control with less effort and less torque on your legs and knees.