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Uninvolved versus target muscle contraction during contract: relax proprioceptive neuromuscular facilitation stretching

PainSci » bibliography » Azevedo et al 2011
Tags: treatment, stretch, muscle, exercise, self-treatment

One page on PainSci cites Azevedo 2011: Quite a Stretch

PainSci notes on Azevedo 2011:

This well-planned experiment tested whether or not the contraction component of a contract-relax stretch actually makes a difference, and clearly found that it does not. The researchers compared a normal CR stretch of the hamstring to a modified one without any hamstring contraction (instead, some other “uninvolved, distant” muscle was contracted). The effect of both stretches was the same — “a significant moderate increase in range of motion.” In other words, it didn’t matter if the hamstring was contracted or not — with or without a contraction, the result was the same. This strongly undermines the central claim of CR-PNF stretching.

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVE: The purpose of this study was to compare the acute effect of the contract-relax (CR) stretching technique on knee active range of motion (ROM) using target muscle contraction or an uninvolved muscle contraction.

DESIGN: pre-test post-test control experimental design.

SETTING: Clinical research laboratory.

PARTICIPANTS: Sixty healthy men were randomly assigned to one of three groups.

INTERVENTIONS: The Contract-Relax group (CR) performed a traditional hamstring CR stretch, the Modified Contract-Relax group (MCR) performed hamstring CR stretching using contraction of an uninvolved muscle distant from the target muscle, and the Control group (CG) did not stretch.

MAIN OUTCOME MEASURES: Active knee extension test was performed before and after the stretching procedure.

RESULTS: Two-way between-within analysis of variance (ANOVA) results showed a significant interaction between group and pre-test to post-test (p < 0.001). Post-hoc examination of individual groups showed no significant change in ROM for the CG (0.8°, p = 0.084), and a significant moderate increase in ROM for both the CR (7.0°, p < 0.001) and MCR (7.0°, p < 0.001) groups.

CONCLUSIONS: ROM gain following a CR PNF procedure is the same whether the target stretching muscle is contracted, or an uninvolved muscle is contracted.

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