The Metabolic Wheel is a great cardiovascular training system. It is a timed program which can be used to supplement standard aerobic based training. It also develops local muscular endurance based on exercise selection.
The Metabolic Wheel gives you the framework to design an infinite amount of metabolic workouts that can be adjusted based on style of grappling, match duration, and tempo that the grappler uses.
Each training session ranges from 20-30 minutes based on the rep ranges used. Your work rate stays constant but the intensity of the work will vary based on the exercises you chose. Additional rest can be taken as needed
The program can also be used as a volume supplement to a strength block. Many programs that I design for athletes are 80% strength and 20% metabolic. This allows the athlete to maintain fitness and provides positive body composition changes.
I would advise grapplers that are peaking for competition to complete this metabolic based program at least twice per week.