MIRZAEI, B.; NIA, F. R.; SABERI, Y. Comparison of 3 different rest intervals on sustainability of
squat repetitions with heavy vs. light loads. Brazilian Journal of Biomotricity, v. 2, n. 4, p. 220-
229, 2008.The purpose of this research was to compare differences between 3 different rest
intervals on sustainability of squat repetitions with heavy vs. light loads. Eighteen resistance
trained men volunteered to participate in this study (age 22.67 ± 1.94 years; body mass 79.54 ±
15.73 kg). All subjects performed 2 testing sessions each week for 3 weeks. During the first
testing session each week, 4 consecutive sets of the squat were performed with 90% of 1
repetition maximum (1RM) and with a 90-, 150-, or 240-second rest interval between sets.
During the second testing session each week the same procedures were repeated with 60% of
1RM. The total repetitions completed and the sustainability of repetitions was compared
between rest conditions and between loads. For each load, significant decline in repetition
occurred between first and fourth set (p = 0.000). And the sustainability of repetitions was not
significantly different between loads (p = 0.076). For each load a significant difference in the
ability to sustain repetitions occurred between the 90-sec and 240-sec rest condition (p =0.000),
and between the 150-sec and 240-sec rest condition (p =0.002). However, the sustainability of
repetitions was not significantly different between the 90-sec and 150-sec rest condition (p
=0.092). These results suggest that when the training goal is development of muscular
endurance, 90- sec should be taken between set and the intensity should be lowered. When the
training goal is maximal strength development, 240- sec of rest should be taken between sets to
avoid significant declines in repetitions. The ability to sustain repetitions while keeping the
constant intensity may result in a higher training volume and consequently greater gains in
muscular strength.
