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Training Cadence for Skimo Racing
What separates fast skimo racers from slow skimo racers? Certainly equipment, technique, transitions, and fueling are all important considerations, but I propose that one simple metric sets fast racers apart from the rest: cadence.
In short, cadence is how many strides a racer takes per minute. It makes no measure of how long those strides might be. Cadence is a measure of pure turnover, and interestingly, one thing in common among all of the fastest racers is a fast cadence.
The fastest world cup skimo racers have a cadence of around 110-115 strides per minute. To make that more intuitive, they stride along to the snare-beats of The Clash’s “Should I Stay Or Should I Go” at 113 bpm.
(If The Clash annoys you too, try some Pretty Lights).
I’ve heard a few theories about why a faster cadence is good for you, but I can’t say that I agree with them. The easiest argument to make is that if I’m taking 10 more steps per minute, then over an hour, I’m 600 steps ahead. The problem is, this assumes that when you change your turnover, your stride length stays the same. It doesn’t; your stride gets shorter. If it stayed the same length, then the advice that I’m giving you now would be equivalent to saying if you just go faster, then you’ll go faster. Duh.
It’s the change in stride length that is the important result of a faster cadence. Whether you shorten your stride and take more steps to maintain the same speed, or if you increase your cadence and have to modify to a shorter stride to avoid exploding, the result is the same: more steps, shorter steps.
The advantage of taking shorter steps is that it changes the muscle groups that you use. By keeping your stride short, you employ muscles that are designed for endurance. When you take bigger strides, you engage muscles designed for power. They’ll carry you for a short distance, but soon you won’t be able to maintain that pace.
To understand why shorter strides are better, you’ll need a quick physiology primer. With few exceptions, like the heart, most of the muscle in your body is called skeletal muscle. The fibers that make up that muscle are divided into two main types: fast twitch and slow twitch. Fast twitch fibers are built to generate power, which is (force x speed). Think of a sprinter coming off the line and you’ve got pure fast twitch muscle. Slow twitch muscle is designed for endurance– it’s not terribly strong or fast, but it can go for a very long time. For those playing along at home, there is an intermediate muscle fiber type which is similar to fast twitch muscle but can become more like slow twitch with training, but that’s a subject for another time.
The critical difference between fast and slow twitch muscle fibers is that they use different sources of fuel. Fast twitch fibers use an anaerobic metabolic system that generates lactic acid and creates an oxygen debt, but as a consequence, they can produce a lot of energy very quickly. A fast twitch muscle is like lighting a match in a jar: it flares brightly for a few moments and then, having consumed all available fuel, it snuffs out. In general, fast twitch fibers will work reasonably well for about four minutes before they tire significantly.
Slow twitch fibers use an aerobic metabolism that produces a lot less umph-per-minute, but importantly, the system replenishes itself as it moves. So with adequate fuel, slow twitch muscle can continue to contract indefinitely. These are the muscles that support you as you stand and walk throughout the day, and they can continue to do so forever provided that they are supplied with fuel. Without going into it here, suffice it to say that you are very well equipped to deliver fuel to slow-twitch muscle during an athletic effort of 1-2 hours, without eating. With training this time can be extended to 5-7 hours or more. If you eat you can go even longer.
So, when you take shorter steps, you employ different body mechanics (read:different angles at your joints) which recruit different muscles to do the work for you. If you’re taking big steps, like taking stairs two at a time, you’ll recruit muscles that use fast twitch fibers and tire quickly. With a shorter stride, you’ll use slow twitch fibers that can sustain an effort for much longer. (For the nerds, with the shorter stride you’re using the gluteus medius in your butt and the soleus in you calf among others, while bigger strides employ the gluteus maximus and gastrocnemius.)
The take away from this breakdown is that by taking shorter strides with a faster cadence, you can maintain the same speed while using muscles that won’t tire as quickly. That said, it is hard to start ramping up the pace in training because your body is used to moving at a certain pace.
Your cadence is a neurologic pattern, defined by what the geeks call a reflex loop. Though you may have all of the slow twitch fiber that you need, you have to neurologically train yourself to take advantage of this system, which means specifically training cadence.
To train cadence, start by first measuring your natural pace. Hit the slopes that you usually use to train and settle into a comfortable but quick pace, maybe 70-80% effort and time how many strides you take in a minute. I suspect that if you’re being honest you’ll find yourself in the 70-80 bpm range, which is fine. That’s your starting point. Next, add 10-15 bpm to that pace and move through these progressively more challenging workouts, which you can incorporate into your training or tours:
-Skin on a flat to slightly downhill track for 10 minutes x 3 at your target pace, with 3 minutes rest between efforts. Adjust your stride so that you don’t become winded,
-Skin on a mild uphill track at your target pace for 3 x 10 minutes. After 10 minutes transition to ski and ski or skate back to your starting point and resume the next set.
-Skin on a moderate uphill track at your target pace for 30-45 minutes, space permitting. Transition and ski to the start, and repeat at least once.
When you’ve cycled through these and can complete them at your target pace, add 5 bpm and start again. The easiest way to keep track of cadence is an annoying iPhone metronome app and some headphones. Less irritating is to search Spotify or Jog.fm for “90 bpm” or whatever speed you need an find a playlist that has been assembled for that cadence. I easily found playlists for 80, 90, 100, and 110 bpm.
In any of these efforts, it’s important that your heart rate doesn’t go through the roof. If it does, then shorten your stride. If you still can’t keep in under control, try 5-10 bpm less as your starting point.
An important aside: I don’t always ski like I’m racing skimo. Like any sane person, I prefer skiing good powder any day. That said, casual, slow touring is the enemy of fast skiing and will undo your neurologic training. When out for a day of touring, try to work in a little bit of faster cadence work to avoid total dominance of the trailbreaking-plod.
Racing and training don’t have to be a death march. Speed up that turnover and you’ll feel better, race better, and potentially even ski more powder. Get out there and train to some techno!
Light gear, light feet, fast feet.