The purpose of this study was to compare the effects of a plyometric exercise on 1 repetition maximum (1RM) squat performance after short (15, 30 second) and long (60-second) rest interval following plyometric training in trained male athletes. The subjects were fifteen trained men [age= 22±1.4 years, Mass=80.61±3.20 kg] who had previous experience in strength training and experience performing plyometric exercises. All subjects performed 4 testing sessions and separated by at least 1 day of rest. Before all testing sessions subjects participated in a warming-up program and it kept constant through all testing sessions. During the first testing sessions, 1RM was assessed in back squat and during the depth jump sessions subjects performed in counterbalanced order a set of 2 depth jump (DJ) 15, 30, or 60-second before each 1RM attempts. One-way repeated analyses of variance with Bonferroni post hocs demonstrate significant differences between 1RM in baseline measurement and DJ sessions (P<0.05). Also, 1RM in back squat significant improved (P<0.05) after 15-second (2.74 %) and 30-second (2.43%) post a set of 2 depth jump. Therefore, these data provides support for the use of plyometric exercise 15 to 30-second before 1RM test to improve maximum strength performance.
