Generally, you would want conduct a ski that is at least 2/3 of the total distance of the Birkie or at least 35 kilometers. On the other hand, evidence is starting to show that doing a full distance effort may not be necessary. Ironman triathlon training has showed us that a goal event can successfully be achieved without ever doing the whole event. A portion – yes, but the whole – appears not. Longer events take a lot out of the body and doing significantly long training bouts can take away valuable energy that might otherwise be best used during the goal event. Practical evidence and sport science has shown that frequency of training as well as ensuring a significant contribution of distance training is done at a low enough intensity can be more important. Level1 training truly attacks the aerobic system instead of medium and medium-plus efforts that recruit both the aerobic and anaerobic systems but this type of training really doesn’t maximize or push either system effectively.
Marathon training in running has also begun to shift in this manner as well. The world’s best marathoners are consistently becoming the athletes that are great 10 kilometer runners. Some appear to do long distance efforts and others not. The commonality is that they vary their training intensities and they all train frequently.
In general, I would suggest a long over distance ski of at least 35 kilometers in distance to ensure you can maintain endurance for that duration. I would suggest that it not be shortly before the actual Birkie event though. I would suggest 2-3 weeks prior to be safe. The last week should be on capping the energy systems through recovery and good diet. Fuel and hydration during training efforts is also critical to train the body to take in nutrients more efficiently when active. This can be trained and needs to be a consistent aspect of training to minimize the potential of the dreaded bonk.
– by Brian Fish, U.S. Ski Team Continental Cup Coach