You speak on the needs of “competitive tennis players”. Here’s an excerpt from an article written on Andy Roddick’s workout routine in 2009. I’d say he was a pretty decent competitive tennis player.
The link to the article is here:
https://www.askmen.com/sports/bodybuilding_250/282_training-for-tennis-the-roddick-way.html
Training for endurance
When it comes to training for endurance in tennis, you’re going to do a lot of running, both distance running and sprints — and you’ll “switch them off.” Andy Roddick, however, “will never really run six or seven miles at a time,” as he tends to “focus more on power-speed type running drills.”
In tennis,
recovery as an aspect of endurance is as important (if not more so) than the ability to play for an hour or longer. As such,
your training should reflect the experience on court, where you’ll only have 25 seconds to recover between sets. To achieve this, Roddick does a lot of “straight track work.” With only a minute and a half to recover between sets, Andy will run “30-, 40-, 60-meter sprints (8 to each one)” and the following day he’ll do five or six 300s (300 meters). “With me, my focus is more on how quickly I’m able to recover from something tough.”