Level: Age group finisher
Duration: 1 week (can be repeated)
Hours: 16 hours 
 
This is a one week program that incorporates cross country skiing into the weekly training mix for athletes who live in locations where winter has extended periods of snow, and easy access to outdoor ski training. It can be repeated for a couple of weeks, or for the whole winter ski season for athletes in such locations and climates.
 
Cross country skiing has fantastic carry over for triathlon. Not only does it give the legs an outstanding workout, but it has great application for your arms as well.
It checks all the boxes for triathlon:
The arm movement works the triceps, which are so dominant in swimming. Each movement is finished off with an acceleration that helps with biomechanics used during the swim. Swim check.
 
Freestyle (or skating) cross country skiing builds significant thigh power and works the glutes with every movement. Bike check.
 
The overall cardiovascular workout is absolutely second to none. Run check.
 
The session is performed with no eccentric pounding, so if it’s done correctly one can allow longer workouts for 1hr 30min without the risk of bone stress injuries. Obviously a downside is if you’re not strong in the knees then poor technique while skating will be a problem.

The fix, learn to ski with a better technique or use the classic style, which is still a terrific workout.
 
With a good winter of skiing along with a small period of time to get used to the bike again, and that can be as little as four weeks, you are actually able to improve your triathlon by using ski preparation.
 
Assumptions:
This 'Age Group Winter Ski and Triathlon Program - 16 hours per week' is provided under the assumption that the participant has a basic level of fitness, has been actively training recently, is injury free and can accomplish the following:
Swim: Complete 1500m of swimming without stopping.
Bike: Complete 60 minutes of cycling without stopping.
Run: Complete 45 minutes of running without stopping.
Cross Country Ski: Complete 45 mins