Too often I see training programs that will simply say "four sets of fifteen" of a certain exercise. All trainers should use max testing to establish limits for their athletes. I have found that using percentages of your max to lift to near failure will help achieve the most gains in a strength program. Based on your goals (strength building, endurance, toning and sculpting, etc) this principle can help. Tempo of the exercise will also contribute to the gains achieved. Mix slow controlled exercises with faster, quick-twitch exercises and stretching to increase strength and power.
During the off-season you have a recovery phase and a strength phase. During the recovery phase, focus on rest, rehabilitating any injuries, stretching and correcting any muscle system imbalances, i.e. hamstring to quad strength. During the strength phase, work at 75-95% of the athlete's rep max for 5-8 sets of 3-7 reps. It is very important to add tempo exercises and stretching, and to train the muscle system in accordance to the action in the sport to be performed. For example, baseball players should not lift like football players.
When working out preseason and in season, an endurance program is recommended to prevent injuries and keep the gains made in the off-season. I recommend using 45-60% of the athlete's rep max for reps of 15-20. Stretching, balance and core exercises should be performed daily during this phase.
For more information about building an appropriate exercise regimen for an athlete, contact a FAST facility near you, or visit www.fast-training.com.