Effects of differing intensities of static stretching on jump performance.

Acute bouts of static stretching have been shown to impair performance. Most published studies have incorporated static stretching that stressed the muscle(s) to the point of discomfort (POD). There are very few studies that have examined the effects of submaximal intensity (less than POD) static stretching on subsequent performance. Ten participants were pre-tested by performing two repetitions of three different stretches to assess range of motion (ROM) and two repetitions each of five different types of jumps. Following pre-testing, participants were stretched four times for 30 s each with 30 s recovery for the quadriceps, hamstrings and plantar flexors at 100% (POD), 75% and 50% of POD or a control condition. Five minutes following the stretch or control conditions, they were tested post-stretch with the same stretches and jumps as the pre-test. All three stretching intensities adversely affected jump heights. With data collapsed over stretching intensities, there were significant decreases in jump height of 4.6% (P=0.01), 5.7% (P<0.0001), 5.4% (P=0.002), 3.8% (P=0.009) and 3.6% (P=0.008) for the drop jump, squat jump, countermovement jump (CMJ) to a knee flexion of 70 degrees , CMJ using a preferred jump strategy and short amplitude CMJ respectively. An acute bout of maximal or submaximal intensity stretching can impair a variety of jumping styles and based on previous research, it is hypothesized that changes in muscle compliance may play a role.