Sports Medicine Research: In the Lab & In the Field: Acute Gains in Motion After Single Bout of Stretching Predicts Short-Term Gains (Sports Med Res)
Monday, September 15, 2014

Acute Gains in Motion After Single Bout of Stretching Predicts Short-Term Gains

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

Beltrao 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.

We 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 group.

The 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?

Written by: Jane McDevitt, PhD
Reviewed by: Jeff Driban

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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

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