Ask several players if they want to be "stars", and the answer will be a resounding YES. If you immediately ask them if they workout everyday, then you will hear YES once again, but half of them will be lying or "half-assing" the effort truly required to improve and succeed. With this being said, here is an off season workout that high school players seeking scholarships, and NCAA players looking to play well next season should be doing regularly. In fact, professional players could improve with this workout as well.
During the off season I suggest that each player workout every day. You eat, drink, breathe, and sleep everyday, therefore it only makes sense to workout everyday. It is common knowledge in the body building community that muscles are best developed when exercise, rest, and proper nutrition are combined. The key is to have "rest days" (1 or 2 per week) that are not strenuous. On "rest days" each player does light exercises, oe stretching, but they do not completely abstain from conditioning themselves.
For basketball purposes, cardiovascular, muscular, and skill development are the primary goals during the off season. I highly suggests that the most taxing parts of the workout be done early in the morning. Here is a sample morning workout.
1) 5 mile bike ride. If you time yourself and try to improve each day, then bike riding will be both effective and rather enjoyable. By riding a bicycle players can improve their endurance, and balance without putting a lot of wear and tear on their knees.
2) Ball Handling Workout. Every player is expected to be a good ball handler. Most simply are not. In fact, I laugh TREMENDOUSLY at "professional" players that cannot dribble the basketball. All elite players can handle rhe basketball well. Therefore, all ball bandling workouts should be done daily, even on "off days" along with the bike riding.
Pistol Pete Maravich practiced ball handling drills all of his life. Maravich stated several times that they are the reason for his basketball success. For those that do not know, "Pistol Pete" is the NCAA all-time leading scorer (44.2 ppg), and he did it over 3 seasons because freshmen were not allowed to play back then, and the NBA only drafted seniors. No one else has come within 1000 points of his record, so his comments speak volumes. Those that do not know which drills to use can find a million on YouTube. There are no legitimate excuses for any player not to practice ball handling.
3) Full Body Workout. If you have access to weights, then excellent. If not, then do bodyweight exercises. You will see serious progress if you focus on doing each excercise with proper form and slowly. By doing each exercise in this manner the targeted muscles are forced to work without the benefit of momentum which is much much harder.
My suggestion is that each athlete do 12 exerceise total. Three "push" exercises (ex: push-ups); three "pull" exercises (pull-ups); three lower body exercises (ex: standing bicycle crunches); and three midsection exercises. The midsection exercises should work the abdominals, obliques, as well as the lower back. That's right, A THREE AREAS of the midsection!!!
4) Basketball Skill Workout. This part of the workout wiil probably need to be done in the evening because many student athletes work during the summer. This is not a problem. In addition, when putting up a lot of shots, the greats shoot 500 daily, then a rebounder is definitely necessary.
I used to "barter" my rebounding services. Meaning this, I found workout partners who were as committed to improving as I was, and we rebounded for each another. We would alternate after every 25 made shots. After taking hundreds of shots, each day we would end our sessions with full court one on one games (best of three). Those that do this part of the workout daily will become different (much better) players GUARANTEED. The players that do the first part of this workout will have the improved physical strength and endurance to make a "statement" on the court. The few that do all of this during the off season will also become "difference makers", and the players that "chill" will be their victims when the season begins.