Exercising alongside them, as a group cycling instructor,
I'd say this workouts are a 7 on the 1-to-10 scale, with 10 to be the Leadville 100:

WORKOUT ONE: "The Shredder" 8 a.m. to 10 a.m. Circuit training, University of Colorado Anschutz Overall health Center

Pre-warm-up: One mile, alternately p57 hoodia running and walking, laps around an inside track.

Warm-up: One lap running around an area neighboring the ability.

Station 1: Two one-minute teams of jumping rope; one minute of Battle Rope exercise, grasping the ends of two giant ropes and swinging them down and up.

Station 2: Two one-minute sets of abdominal crunches; about a minute of boxing with trainer Chris Powell.

Station 3: Sets of sprints, as much as possible in three minutes, first to some cone about 25 feet from the starting point, followed by a sprint to some cone
about 50 feet in the starting point.

Station 4: Two one-minute teams of mountain-climber exercise (balancing on palms and toes, alternately pulling each knee to the chest rapidly), repeatedly
flipping on the wet, slippery 200-pound tire for one minute.

Station 5: Three minutes of football drills, including ladder drill, sidestep agility drill, push-ups and sprints.

Station 6: Three minutes of  slimming factorsoccer drills, running and passing a football with a couple. Harder than it sounds.

Repeat until 2 hours are up.

WORKOUT TWO 11 a.m. to noon. CrossFit deadlifts, Bladium Cross Fit studio

Load a barbell, beginning with at least half your body weight in plates. Squat with feet shoulder-width apart. Grasp barbell.