Correlation between
acute and short-term changes in flexibility using two stretching techniques

NB., Ritti-Dias RM., Pitangui ACR., De Araujo RC. Int J Sports Med. 2014; ahead
of print

Take Home Message: Acute
changes in flexibility after either static or PNF stretching predict the gains
in flexibility after a 7-day stretching program.

often try to improve flexibility among our patients; but yet improved
flexibility often depends on the type and duration of a stretching regimen and
various patient characteristics. If we could predict gains in flexibility this
would help us develop more individualized flexibility plans. One strategy could
be to determine if a response to an acute bout of stretching could predict
flexibility gains over time. Therefore, the purpose of this study was to
determine whether increases in flexibility after a single session predicted
increases in flexibility after a short-term stretching training program of static
stretching or proprioceptive neuromuscular facilitation (PNF). The researchers assessed 70 right handed,
young adults’ active knee extension and then randomly assigned each
participants into 1 of 2 stretching groups. To assess active knee extension, 2
researchers maintained proper hip and knee positioning (left leg and hip in
full extension; right hip flexed 90o), and a third researcher used a
goniometer to measure active knee extension. They included participants who
could not achieve more than 160 degrees of right active knee extension. Forty
participants completed the stretching program (50% female, ~22 years) and 30
participants performed PNF stretching (60% female, ~23 years). The stretching
programs consisted of seven consecutive days, which began each day with a
measurement of the participants’ active knee extension. The static stretching
was performed utilizing a pulley system with a 7 kg weight to enable passive
flexion through the maximum range for 1 minute. Participants in the PNF
stretching program were taken through passive hip flexion by the researcher
until discomfort became unbearable, and this position was held for 30 seconds.
After that, the participants performed a maximal isometric contraction of the
hip extensors against the researcher’s shoulder for 6 seconds, and then was asked
to relax. This procedure was repeated twice. The researchers evaluated active
knee extension before and after the first session as well as one day after the
intervention. The participants had small flexibility gains, but there were no
difference between groups. Both groups experienced more short-term (1 week) range
of motion gains than acute gains after one session. The flexibility after the
first intervention session was strongly related with changes after the training
program in both groups. Additionally, the acute gains in active knees extension
after the first session were moderately predictive of the short-term gains in either

researchers found increases in flexibility after the first stretching session
predicted the flexibility gains after a one-week training program, regardless
of the type of stretching task. It is interesting that both stretching methods
increased active knee extension to a similar extent. This finding could be
attributed to similar stretching times (1 minute of static stretching versus 1
minute and 12 seconds of PNF stretching), which supports the notion that the
total duration of the stretch matters a great deal to flexibility gains. The
results from the study should be taken with caution due to the limited
intervention time as well as the restricted number of stretching exercises. It
would be interesting to learn if the response after a single session is
predictive of changes after a 6-8 week program (or longer). Clinically, this is
an important topic since many patients undergo short rehabilitation programs
and the ability to predict flexibility gains could help us optimize treatment
strategies as well as consider if the patient achieved or fallen short of the
flexibility goal.

Questions for
Discussion: What method of stretching do you prefer? How long do you put an
athlete on a stretching program for if they are stiff? Have you found that
athletes who do not improve range of motion after the first session tend to
fail to show long-term improvements?

by: Jane McDevitt, PhD
by: Jeff Driban


Beltrão NB, Ritti-Dias RM, Pitangui AC, & De Araújo RC (2014). Correlation between Acute and Short-Term Changes in Flexibility Using Two Stretching Techniques. International Journal of Sports Medicine PMID: 25144437