In sport I define endurance as efforts lasting longer than 20 seconds. I know many would argue with this, but I am looking for the tipping point in effort where you can no longer hold your maximum power output. This typically takes place at about 10 seconds plus. It also takes place at about 6-8 reps of maximum output in most power exercises.
In other words if you were to measure your vertical jump, how many jumps can you get before the height of the jump begins to diminish. How efficient are you at producing power dictates the total number of jumps.
We utilize cluster sets for power in a very interesting and unique fashion to insure our athletes are producing higher percentages of power at the end of a game. There is more and more research looking at cluster set training. It allows the athlete to spend much more time at a higher power output. You group the repetitions into small groups of mini-sets to allow the athlete to perform a higher amount of volume at this higher output. It is a game changer! Especially for endurance athletes. You have to design the reps and rest and total time to match the needs of the sport.
In the video ( https://youtu.be/-eLqtA_nEc8 ) Matt Lurie, a college tennis player, is performing power clusters on the Versapulley. The effort designed with 4 pulls, within 10% of his maximum velocity, every 15-20 seconds. So he is getting about 12 reps per minute. He completed 3 sets of 3 minutes total. So he was able to get an overload of almost 40 reps in each set at close to 90 percent of his maximum power output. So in total 120 total reps. You need to have a great foundation of fitness to accomplish these efforts. The clusters allows Matt to improve his efficiency of power output.
If you have athletes that require high power output for long periods of time this is a game changer.
Truth in Fitness:
Jacques DeVore, CSCS