By Maria Stuber
There are many physiological systems that play a role in performance gains. Total conditioning can be a result of cardiovascular endurance, muscle strength and power, coordination, speed or flexibility. To optimize performance in cross country skiing, it is necessary to train all systems with the appropriate balance that is specific to the sport. The focus of this article will be on distance training and how it should be balanced into total conditioning for cross country skiing. Distance training makes up around 80 percent of the yearly training volume for cross country skiers. Therefore, it is imperative that this training is done correctly.
Distance training uses mostly aerobic metabolism. Aerobic metabolism is oxygen-dependent and yields significantly more energy than anaerobic metabolism. In addition, aerobic metabolism has the potential to break down fats instead of glucose. Glucose stores are used up relatively quickly, but fats are essentially limitless in the healthy human body. The drawback with aerobic metabolism is that it is relatively slow and cannot provide enough energy for quick, high intensity exercise.
During any exercise, both aerobic and anaerobic systems work together to provide energy. At low intensities, aerobic metabolism is dominant because there is plenty of time to break down and use fats. Then, the anaerobic metabolism input picks up as the exercise intensity level increases.
The purpose of distance training is to increase the amount of time that aerobic metabolism is dominant and to increase the efficiency of the aerobic systems. Therefore, athletes should gradually increase the length of their distance training instead of increasing the pace. Increasing the pace will trigger more anaerobic work and lactic acid production, which can be very taxing on the body. Anaerobic training is essential for optimum performance, but it must be highly controlled and done in much shorter bouts. If distance training is done too fast, the body will fatigue very quickly and results will suffer over time.
The list of benefits associated with proper endurance training is very long and includes increased blood volume, increased heart volume, increased maximum cardiac output, increased stroke volume and a decreased resting heart rate. Benefits also include increased maximum oxygen uptake, increased capillary density, increased mitochondria density (at the cellular level) and increased activity of citric acid cycle enzymes (chemical reactions in all living cells that use oxygen as part of cellular respiration).
In order to maximize the benefits of distance training and minimize unwanted fatigue, exercise scientists have identified “training zones” to help athletes and coaches know that they are getting the desired response from a workout. There are five physiological training zones and all distance training must be done in zones one and two.
Zone one (or level one) is the easy, aerobic endurance and over distance zone. This zone is best defined as 60 percent of an athlete’s maximum heart rate, 50 percent of an athlete’s maximum oxygen uptake (VO2 max), or a blood lactate level at 2.0 mmol or lower. In zone one, the body is operating on aerobic energy systems almost entirely and oxygen must be readily available. This zone is typically used for low- intensity easy-distance training, recovery sessions and over-distance training. It feels extremely easy and may be difficult for skiers to become accustomed to if they typically ski too fast.
Zone two (or level two) is the general endurance zone where the anaerobic energy contribution is slightly increased. However, aerobic energy systems remain dominant. Zone two is defined as 75 percent of maximum heart rate, 70 percent VO2 max, or a blood lactate level between 2 and 3 mmol. This level can be maintained for a long time before an athlete will become fatigued. Training in this zone should also feel relatively easy. When an athlete cannot easily carry on a conversation during a distance training workout, he/she is probably going too fast.
General endurance can be done in zone two; however, long workouts will be more productive in zone one. Training at the top of this zone (or slightly above) too often can be very dangerous but is common for both recreational and serious athletes who lack educated coaching support. Here, athletes often find themselves in a performance slump because they are training too fast to become efficient at low intensities, and too slow to become efficient at high intensities, yet they still feel the fatigue of high intensity training.
Zone three, four and five have higher anaerobic contribution and are used exclusively for interval training. Although it is very important to do some training in these zones, they should be avoided during distance training. Eighty percent of the total yearly volume is endurance training, while intervals and strength fill up the other 20 percent. Consequently, if endurance training is not done correctly, 80 percent of the total yearly training is not done correctly. Surprisingly, training too hard during distance workouts can have a more profound negative effect on performance than training too slow during interval sessions. All serious athletes should make sure that they know the heart rate values that correspond to their physiological training zones so that they do not make this common mistake.
In the early summer months, distance training can be kept very general. Activities like running, biking, canoeing and kayaking are just fine for working the aerobic energy systems and building an endurance base. As winter approaches, specificity becomes more important and serious skiers should get out on their roller skis three days to six days per week, depending on time availability and training volume. In addition, it is recommended that one of these workouts is designated an “over distance” workout. Over distance is always done in level one and it should be 1.5 to two times longer than a normal workout.
Long, slow roller skis are also an exceptional opportunity to get rid of bad habits and engrain good technique. Watch some World Cup video on the Internet before distance training. Find training partners that feel comfortable reminding you what you need to work on. In order to permanently fix technique flaws, skiers must develop new muscle memory. This takes hours of focusing on one thing and doing it perfectly every single stride.
Distance training is the most basic and most important component of cross country ski training. Although it seems straightforward, many athletes train too hard and miss out on the desired physiological benefits. Slow down, and do not forget to think about your technique.
Maria Stuber is a member of the CXC Elite Team. She is a graduate of Northern Michigan University, where she was captain of the women’s cross country ski team and received NCAA All-Region and All-American academic recognition.