I really enjoy cross-country skiing in the winter.
That's awesome, I do too! I love the rich history behind it, there were Norwegian army units skiing for sport all the way back in the 18th century.
Why did the units ski?  Were they on patrol?
Ski patrol
Ski patrols are organizations that provide medical, rescue, and hazard prevention services to the injured in ski area boundaries, or sometimes beyond into backcountry settings. Many have technical-medical certifications, such as Outdoor Emergency Care (OEC) provided by the National Ski Patrol (USA), that are specific to the winter-season environment and providing emergency medical services in remote locations. Many patrollers also hold EMS issued credentials, such as emergency medical technician or any other pre-hospital care certification. Due to the
Military patrol
Military patrol was a team winter sport in which athletes competed in cross-country skiing, ski mountaineering and rifle shooting. It was usually contested between countries or military units. 
The military patrol competition encompassed 25 kilometer cross-country skiing (15 km for women) and rifle shooting. The size of the patrol was four members. The total climb had to be from 500 to 1200 meters (300 to 700 for women). The rules were very similar to modern biathlon. Traditionally the participating patrol