You’re only going to be as strong as your weakest link. The major muscle groups that perform traditional exercises are known as your prime movers (e.g., pecs, lats, quadriceps, hamstrings, gluteus maximus, deltoids, etc.). Often, an athlete's weakest link will be his behind-the-scenes muscles, (e.g., rotator cuff, middle and lower trapezius, serratus anterior gluteus medius, abdominals, etc.). Incorporating exercises to strengthen these muscles will reduce the chance for muscle imbalances and decrease your risk for injury. The better able you are at recruiting these muscles, the more potential you have of increasing the strength in your prime movers.