• PNF and Movement
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• 제16권2호
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• pp.229-238
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• 2018

Purpose: This study aimed to compare the immediate effects of various contract-relax (CR) techniques on the peck force and passive range of motion (ROM) of knee extension. Methods: This study recruited 17 adult males and females who obtained below $90^{\circ}$ in straight leg raising. The subjects randomly performed one of three different CR techniques (direct CR, indirect CR, and modified CR) on the right knee extension four times per day for three days. The subjects' peck force during each CR and their passive knee extension on the hip at a $90^{\circ}$ flexed position before and after each CR were measured. Results: The peck force was significantly higher in the direct and modified CR than in the indirect CR. The ROM in the passive knee extension significantly increased after direct and indirect CR. Comparing between each CR, the passive knee extension range was significantly more improved in the direct and indirect CR than in the modified CR. Conclusion: Direct and indirect CR are more effective than modified CR in the ROM of passive knee extension. The study results suggest that the modified CR did not have the same effect on the ROM of the knee extension as the direct and indirect CR and that further research is needed to recruit more subjects and to determine the effects on different muscles after modified CR.

• PNF and Movement
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• 제14권1호
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• pp.7-14
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• 2016

Purpose: The purpose of this study was to determine the effectiveness of direct and indirect methods of contract-relax techniques in proprioceptive neuromuscular facilitation (PNF) stretching for improving hamstring flexibility. Methods: Twenty-six subjects were randomly assigned to either a direct contract-relax technique group or an indirect contract-relax group. For each group, stretching intervention was performed three times a week for a period of two weeks, with 12 seconds for the contraction and 10 seconds for the relaxation per once. The direct contract-relax technique for hamstring flexibility was applied by asking the subject to press down on the shoulder of the trainer in the straight leg-raising position. Conversely, the indirect contract-relax technique was performed by raising the leg with resistance. To facilitate a comparative analysis of hamstring flexibility between the two groups before and after the stretching intervention, two-way repeated ANOVA was performed. Hamstring flexibility for each group was measured using a passive straight leg-raising test. Results: The results showed significant improvement in hamstring flexibility for all subjects in the two groups. However, there was no significant difference between the groups. Conclusion: In conclusion, both direct and indirect contract-relax techniques are confirmed to be useful for improving hamstring flexibility. The choice of suitable technique has to be made individually according to the condition of each subject.

• PNF and Movement
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• 제14권1호
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• pp.59-65
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• 2016

Purpose: The purpose of this study was to review articles in order to establish optimal contraction intensity and duration in the performance of relaxation techniques for maximal increase in range of motion. Methods: The Cochrane, EBSCO, Embase, Medline, ProQuest, PubMed, ScienceDirect, and Scopus databases were used to search articles from 1990 to January 2016. The search terms were "contract relax," "hold relax," "muscle energy technique (MET)," and "proprioceptive neuromuscular facilitation (PNF) stretching." Only experimental human studies (randomized controlled trials) that compared the effects of varying intensity and duration of isometric contraction were included. Non-English language and unpublished studies were excluded. Results: A total of 2,156 articles were initially identified, with only five eventually meeting the inclusion and exclusion criteria. Three studies compared the effects of varying intensity in isometric contraction and two studies compared the effects of varying duration in isometric contraction with regard to range of motion (ROM). Two articles suggested that submaximal voluntary isometric contraction was more effective than maximum voluntary isometric contraction (MVIC) in the improvement of ROM. One article showed that a longer contraction time led to greater increases in ROM. Conclusion: Submaximal voluntary isometric contraction was recommended during contract-relax exercises in healthy people. Lack of evidence makes it difficult to suggest the optimal duration of isometric contraction during relaxation techniques. For future research, high-quality evidence will be needed to establish the optimal contraction intensity for maximum improvement of ROM.

• PNF and Movement
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• 제17권2호
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• pp.263-274
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• 2019

Purpose: This article was conducted to determine the immediate effects of unilateral contract-relax (CR) stretching on contralateral knee extension range and to compare both sides of the knee extension range between experimental and control groups. Methods: This study recruited 16 adult males and females with straight leg raising abilities below $90^{\circ}$. The subjects were randomly divided into an experimental group and a control group comprising 8 subjects each. The experimental group performed direct CR stretching on the right hamstring muscles with straight hip extension adduction, and the control group performed indirect CR stretching on the right hamstring muscles with straight hip flexion abduction. Each group performed CR stretching 4 times with 4 repetitions comprising 10 sec of contraction and a 10 sec break between repetitions. Before and after the CR stretching exercises, the subjects' passive knee extensions were measured at the hip in a $90^{\circ}$ flexed position. The subjects' peak force on the right leg and peak pressure on the left leg during each CR stretching exercise were also measured. Results: After doing CR stretching 4 times, each group showed a significantly increased passive knee extension range on both sides, and there was no difference in the passive knee extension ranges between the groups. The peak force on the right leg was significantly higher in the experimental group than the control group. There was no difference in peak pressure between the groups. Conclusion: After applying unilateral CR stretching, the study subjects experienced a significantly increased passive knee extension range on the contralateral side. For patients who find it difficult to apply stretching techniques to knee joints directly, the use of the proprioceptive neuromuscular facilitation technique of CR stretching may be useful in improving the range of the knee joint on the contralateral side without direct treatment.