by Major General Konstantin Fyodorovich Borodin of the Soviet Army Medical Service. He underwent physical and psychological testing conducted at Central Aviation Scientific-Research Hospital, in Moscow, commanded by Colonel A.S. Usanov, a member of the commission. The commission also included Colonel Yevgeniy Anatoliyevich Karpov, who later commanded the training centre, Colonel Vladimir Ivanovich Yazdovskiy, the head physician for Gagarin's flight, and Major-General Aleksandr Nikolayevich Babiychuk, a physician flag officer on the Soviet Air Force General Staff to the Commander in Chief of the Air Force. The commission limited their selection to pilots between 25 and 30 years old. The chief engineer of the programme Sergei Korolev also specified that candidates, to fit in the limited space in the Vostok capsule, should weigh less than and be no taller than ; Gagarin was tall. From a pool of 154 qualified pilots short-listed by their Air Force units, the military physicians chose 29 cosmonaut candidates, of which 20 were approved by the Credential Committee of the Soviet government. The first twelve including Gagarin were approved on 7 March 1960 and eight more were added in a series of subsequent orders issued until June. Gagarin began training at the Khodynka Airfield in central Moscow on 15 March 1960. The training regimen involved vigorous and repetitive physical exercises which Alexei Leonov, a member of the initial group of twelve, described as akin to training for the Olympic Games. In April 1960, they began parachute training in Saratov Oblast and each completed about 40 to 50 jumps from both low and high altitude, over both land and water. Gagarin was a candidate favoured by his peers; when they were asked to vote anonymously for a candidate besides themselves they would like to be the first to fly, all but three chose Gagarin. One of these candidates, Yevgeny Khrunov, believed that Gagarin was very focused and was demanding of himself and others when necessary. On 30 May 1960, Gagarin was further selected for an accelerated training group, known as the Vanguard Six or Sochi Six, from which the first cosmonauts of the Vostok programme would be chosen. The other members of the group were Anatoly Kartashov, Andriyan Nikolayev, Pavel Popovich, Gherman Titov, and Valentin Varlamov. However, Kartashov and Varlamov were injured and replaced by Khrunov and Grigory Nelyubov. As several of the candidates selected for the programme including Gagarin did not have higher education degrees, they