Well, depending on your training program, itís getting to the time of year when something called Ďplyometricsí looms. It might not be- many teams and coaching/training philosophies donít use plyometric strength exercises much, and Iím not here to tell you to change anything!
And, of course, those of us without locked-in training programs simply Ďfeelí like itís something we should be doing now- maybe itís the smell in the air, but our bodies just call out: ďI wanna do plyometrics. Yippee- please, let me do plyometrics. Yahoo.Ē
The following words are an attempt to describe a) what plyometrics is, and b) what, when doing plyometrics, you should be thinking about or focussing on. But first, a note of caution: the nature of plyometrics is such that it places significant stress on major joints and muscle groups, particularly the knees and the back. Before beginning a plyometric routine, ensure you have done the necessary background core and general strength work to be able to handle muscle and joint stress at speed. Donít do your first plyo workout of the year full-out- take it easy, and work up to 100% effort. Ensure you have stretched out before beginning plyo exercises. Despite this article, make sure you have someone lead you through plyometric progressions the first few times you do this workout. Oh yeah, and also, Iím not a coach and I have no certification, so donít take this as gospel!
Plyometric strength is basically a means of developing specific muscular strength and power through the use of own-body-weight exercises. Plyometric strength generally refers to any exercise that involves jumping, bounding, or hopping. Ski enthusiasts have adapted plyometric workouts to be more specific to skiing, and have different exercises for skating and classic techniques. Plyometric strength is important to cross-country skiers for two reasons: 1) it helps to improve balance while moving at speed, and 2) it develops the capacity to have defined power and relax phases in any technique.
Balance, in my opinion, is the single most important contributing factor to efficient movement in cross-country skiing. Being able to balance on one ski frees the body to do all sorts of important things, the most important of which is pre-load. Balancing on one leg allows the upper body to generate maximum force, and allows the ski being balanced upon to generate the maximum force when it is pushed off of. Finally, being able to balance gives any skier the confidence needed, when classic skiing, to put the whole wax pocket into the snow and get good grip on every stride.
Plyometric strength exercises can apply to balance very specifically. Breaking up hopping exercises by forcing balance on one leg is an effective way of figuring out balance points and upper-body position while on skis.
Plyo strength, however, is most useful for developing a defined power-relax stride. Forget the idea that cross-country skiing is long and hard sustained muscle work. Cross-country skiing is (or should be) a long series of powerful, short bursts of energy at a specific moment in the stride, followed by a much longer relax phase during the rest of the stride phase. The longer the relax phase, the longer muscles have to relax and flush out lactic acid while bringing fresh oxygen from the lungs. It follows that, the shorter the power phase, the longer the relax phase. Therefore, to maximize both speed and recovery, a cross-country skier should push very powerfully at a specific moment in the stride, and recover the rest of the time. This is what plyometric strength should be helping to teach. Bounding, hopping, and jumping should all involve one specific moment of very explosive power, followed by a longer rest period.
When thinking about this power-relax part during a workout, try and focus on one of those two aspects at a time. First, think about the correct place to use explosive power- for the double-pole motion, it might be at the moment before your poles hit the snow (or pavement, or grass). Try and muster all your power for that specific portion of the phase. Focus on the power for the first half of your set of that exercise. For the second half of the set, think about the relax- try and feel your muscle recovering during the rest phase. If necessary, slow the tempo down to extend the rest phase until you can feel your muscle fully recovered such that you are ready to inject a lot of power at the correct time. You obviously wonít do this in a race, but this can help to find the correct feeling.
Maybe next article, Iíll describe some specific useful plyo exercises. For now, use the ones you know, and focus on balance (the most important part of technique) and power-relax at the correct times. Youíll feel snappier and more precise in no time- if youíre not, well, I said before that I wasnít certified, so donít come calling me.