[Nice to watch technique without the skier moving out of view! - Mike]
Liz Stephen keeps USSA's High Performance Team busy as she runs through a threshold test and two subsequent threshold intervals of 12 minutes a piece. Liz repeats this test in the preparation phase to recalibrate heart rate zones and to assess training progress. While the threshold rest portion of this movie is executed at a constant grade of 5%, you will notice periods of V1 skiing in the interval portion later in the clips.