Answer by taking a quote from the following article:

Usain St Leo Bolt  (; born 21 August 1986) is a retired Jamaican sprinter and world record holder in the 100 metres, 200 metres and 4 x 100 metres relay. His reign as Olympic Games champion in all of these events spans multiple Olympics. Due to his achievements and dominance in sprint competition, he is widely considered to be the greatest sprinter of all time.

The silver medals from the 2007 Osaka World Championships boosted Bolt's desire to sprint, and he took a more serious, more mature stance towards his career. Bolt continued to develop in the 100 m, and he decided to compete in the event at the Jamaica Invitational in Kingston. On 3 May 2008, Bolt ran a time of 9.76 s, with a 1.8 m/s tail wind, improving his personal best from 10.03 s. This was the second-fastest legal performance in the history of the event, second only to compatriot Asafa Powell's 9.74 s record set the previous year in Rieti, Italy. Rival Tyson Gay lauded the performance, especially praising Bolt's form and technique. Michael Johnson observed the race and said that he was shocked at how quickly Bolt had improved over the 100 m distance. The Jamaican surprised even himself with the time, but coach Glen Mills remained confident that there was more to come.  On 31 May 2008, Bolt set a new 100m world record at the Reebok Grand Prix in the Icahn Stadium in New York City. He ran 9.72s with a tail wind of 1.7 m/s. This race was Bolt's fifth senior 100 m. Gay again finished second and said of Bolt: "It looked like his knees were going past my face." Commentators noted that Bolt appeared to have gained a psychological advantage over fellow Olympic contender Gay.  In June 2008, Bolt responded to claims that he was a lazy athlete, saying that the comments were unjustified, and he trained hard to achieve his potential. However, he surmised that such comments stemmed from his lack of enthusiasm for the 400 metres event; he chose not to make an effort to train for that particular distance. Turning his efforts to the 200 m, Bolt proved that he could excel in two events--first setting the world-leading time in Ostrava, then breaking the national record for the second time with a 19.67 s finish in Athens, Greece. Although Mills still preferred that Bolt focus on the longer distances, the acceptance of Bolt's demand to run in the 100 m worked for both sprinter and trainer. Bolt was more focused in practice, and a training schedule to boost his top speed and his stamina, in preparation for the Olympics, had improved both his 100 m and 200 m times.

Where did he train at the end of the article?
in preparation for the Olympics, had improved both his 100 m and 200 m times.