coming in two forms, classic or skate, nordic skiing is
the original and hardest way to ski. you use every muscle in your body, and race 5-50k. an average practice for high school is 10-15 miles.
classic is a
back and forth motion,
primarily using your arms
skate is similar to skating on ice, except you also use your arms some, but mainly legs.
there is no stopping because of....
too cold
too long
bad wax
bad snow
sore muscles
darkness
season (skis with wheels)