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studies have demonstrated that an acute bout of static stretching
may cause significant performance impairments. However, there are
no studies investigating the effect of prolonged stretch training
on stretch-induced decrements. It was hypothesized that individuals
exhibiting a greater range of motion (ROM) in the correlation study
or those who attained a greater ROM with flexibility training would
experience less stretch-induced deficits. A correlation study had
18 participants (25 ± 8.3 years, 1.68 ± 0.93 m, 73.5 ± 14.4 kg) stretch
their quadriceps, hamstrings and plantar flexors three times each
for 30 s with 30 s recovery. Subjects were tested pre- and post-stretch
for ROM, knee extension maximum voluntary isometric contraction (MVIC)
force and drop jump measures. A separate training study with 12 subjects
(21.9 ± 2.1 years, 1.77 ± 0.11 m 79.8 ± 12.4 kg) involved a four-week,
five-days per week, flexibility training programme that involved stretching
of the quadriceps, hamstrings and plantar flexors. Pre- and post-training
testing included ROM as well as knee extension and flexion MVIC, drop
and countermovement jump measures conducted before and after an acute
bout of stretching. An acute bout of stretching incurred significant
impairments for knee extension (-6.1% to -8.2%; p < 0.05) and flexion
(-6.6% to -10.7%; p < 0.05) MVIC, drop jump contact time (5.4%
to 7.4%; p < 0.01) and countermovement jump height (-5.5% to -5.7%;
p < 0.01). The correlation study showed no significant relationship
between ROM and stretch-induced deficits. There was also no significant
effect of flexibility training on the stretch-induced decrements.
It is probable that because the stretches were held to the point of
discomfort with all testing, the relative stress on the muscle was
similar resulting in similar impairments irrespective of the ROM or
tolerance to stretching of the muscle.
KEY
WORDS: Flexibility, force, jumps, static stretching.
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