Just like with the pacing exercises, each of these intervals consist of a “work” and “rest” time. The work intervals (8 total) should be 20 seconds, and rest is also 10 seconds.  During the work time, complete the first routine (Jump Rope) until the timer tells you to rest. During the rest period, pace slowly or rest completely. Move to the next exercise (Air Squats) during next work period.  Alternate between those pairs until the timer is done.  That is one completed cycle.  Continue to the next three cycles in the same manner.