Bolt is a perfect example of what we've seen in the past 5-8 years in all sports: a much greater emphasis on cross-training.
In 2006, Bolt's manager Norman Peart said that flexibility training was added to the mix, both before and after Bolt's workouts to help "keep him race sharp for a full season."
Now, his workouts also include plyometric and weight training,
Motley Health says that typically, core exercises for improving performance over 100m and 200m are:
Weighted Lunges with heavy dumbbells
Weighted Squats
Bunny Hops / box jumps plyometrics
Frog Leaps
His coaches, including those at his high school in Jamaica, have always urged Bolt to focus on improving his athletic abilities. The lesson fell on immature ears for the most part, and though his prominence rose, he was plagued by injuries, enamored with fast food and having fun, and relied too heavily on his natural abilities.
According to an interview with the Independent, Bolt gives Glen Mills, who joined him in 2005, much of the credit for developing his talent.
(A very intelligent 1-hour conversation with Mills and Bolt on the Art & Science of Coaching is available at SpeedEndurance.com)
Under Mills, Bolt decided to try to accomplish his full potential, which is where the flexibility training, plyometrics and weight training comes in play along with his running and balance training.
http://www.examiner.com/fitness-in-san-jose/usain-bolt-workout-even-the-fastest-man-on-earth-had-to-train-to-be-an-athlete