Contents
1. Abstract Page 3
2. Intro Page 4
3. Aim Page 5
4. Objectives Page 5
5. Methods Page 5-6
-Statement of Application of the Methods Page 5-6
6. Data Sources Page 6
7. Literature Review Page 6-11
-MET alone Page 6
-Static Stretching alone Pge 6
-Comparison of booth techniques Page 7
-Methods of applying Page 9
-Methods of measure Page 10
-Population Page 10-11
8. Findings Page 11
9. Discussion Page 11-14
10. Conclusion Page 14-15
11. References Page 16-19
ABSTRACT
The purpose of this study was to compare the efficiency of muscle energy technique (MET) and static stretching in treating patients with hamstring injury. Both static stretching technique and MET are mostly used to relieve the pain by increasing hamstring flexibility. However, MET is an advanced technique as compared to static stretching technique and even though all produce significant improvements in reducing of hamstring injuries, MET is more effective in the long-run. Biswas & Alagingi (2018) performed a study that confirmed that MET causes better improvements than static stretching. Other researchers agree with Biswas & Alagingi (2018) while others disagree with some points. For instance, McMillian, Moore, Hatler, & Taylor, (2006) found no significant difference in the effects of either dynamic or static stretching. One research that agreed with Biswas & Alagingi (2018) was that of Adkitte, Rane, Yeole, Nandi, & Gawali (2016) which also identified that MET caused better stretching to the hamstring than static stretching. This study performed a systematic review of various studies comparing MET and static technique in treating patients with hamstring injuries. The studies used different muscles groups or different muscles under examination as well as different populations, for example, professional footballers, basketball players, athletes, women, and elderly among others. Most of the findings from the studies revealed that MET and other methods of stretching including static stretching technique are equally effective. However observation reveal that MET is more effective in increases when applied with other stretching techniques. This paper concludes that it is important for clinicians to appropriately chose a technique or an intervention for decreasing muscle tension depending of the genesis of its tightness. It tells that MET should be selected over static stretching because it is more effective but it should be used in combination of other techniques to derive maximum benefits for the patients.
INTRODUCTION
Effect of muscle energy technique and static stretching on hamstring flexibility in healthy male subjects
Muscle energy techniques are pre exercise methods used by sportspeople to improve the strength and flexibility of their muscles. Performance measures may improve or fail depending of the pre exercise procedures. One important aspect in order to improve muscles abilities and exercise outcomes is aerobic warming. It is because it causes relevant stretching, and in effect, improves the flexibility of the muscles. Moreover it also improves the performance of the muscles and prevents the possible injuries during the exercises. Among most common causes of injuries related to exercise is hamstring strain. Hamstring strain usually occurs in case if there is lack of flexibility (O’Sullivan, Murray, & Sainsbury, 2009). That why in the pre exercise routine, the most important are changes is the hamstring flexibility. Statistic stretching is the method of stretching the muscle to its maximum length and keeping the position for some duration. This is different from the dynamic stretching where moving are based and start from a neutral to its greatest stretch while moving it back and forth. Static stretching has been proved by many researches to minimize cases of injury and improve recovery from injury, if any. However, it also has some bad effects on the performance of the individual.
Static stretching is a concept whose definition derives from the term of the connective tissues as they relate to the flexibility of hamstring. According to Biswas and Alagingi (2018, p140), the changes in the length of the muscles interfere with the point at which the muscle best performs in terms of generating tension. When a muscle become less flexible, there are more possibilities to get injuries than when it is flexible. That why stretching is very important in the muscle exercise because it guarantee the changing of the length in the soft tissues. When flexibility is enhanced, the Total Range of Motion (TOM) will definitely improve. To achieve this, Fred Mitchell Sr and Jr came up with the idea of Muscle energy technique (MET) (Biswas & Alagingi, 2018). MET is based on the voluntary contraction by moving the limb in a specific direction against or with therapist`s pressure which put direct and significant influence on the muscle length. Many journals describe that MET is more effective than static stretching in improving the hamstring flexibility (Halbertsma et al, 1999 p407). The main reason for this difference is the better stretch recorded in MET as compared to static stretching. Murphy (1994 p55) also agree that static stretching was quite effective in the dynamic stretching while MET shows more positive outcome as compare to static stretching between males who was not injured. However, in the research done by Waseem, Nuhmani, and Ram (2010) entitled “Comparative effectiveness of static stretching and muscle energy technique on hamstring flexibility in normal Indian collegiate males,” it was proved that static stretching caused better flexibility of hamstring than MET compared to. Much of the literature that point out that MET is weaker in terms of achieving the flexibility of hamstring assert that MET is not appropriate for the healing of an injury.
Traditionally, stretching exercises have been used by healthcare practitioners and other therapists in programs for recovery and training. Studies show that when patients is involved in physical performance that entails maximum strength, there is an effect on the number of repetitions and total volume differently regarding to each form of stretching. There are several forms of stretching; dynamic stretch, the static stretch, proprioceptive neuromuscular facilitation stretching (PNFS), and pre-contraction stretchings. It is important that stretching can improve flexibility as well as various motions in the body joints. Improved flexibility of an individual presents many benefits, for example, enabling the muscles to work effectively, helping the joints to move through their full range of motion, decreasing the risks of injuries, and improving the performance of physical.
Ballantyne, Fryer, & McLaughlin (2003 p59) explain MET is a manual technique that is used by physiotherapists targeting the soft tissues. This technique also cause that the joints are mobilized. It is a technique developed by osteopaths and used by manual therapy professions across the world. Many scholars use different names to this technique with some calling it active muscular relaxation technique while others refer to it as a muscle energy technique. Ballantyne et al (2003) their study on the effect of muscle energy technique on hamstring extensibility found that MET contributes to lengthening a muscle that has been shortened. It also helps in draining the lymphatic system and the blood or fluid and also has the ability to increase the range of motion.
AIM
The purpose of the document is the comparison of two stretching techniques as MET and Static Stretching to reveal that what improvements in Range of Motion can it cause in relevant muscles as Hamstring Muscle Group.
OBJECTIVES
The study will compare effectiveness of the two stretching techniques the targeted population was actively participated in physical activity as also study was conducted on injured examples. Target of the study is mixed, so man and women young as also older. Study mainly was conducted in laboratories either clinics. Main purpose of the project was to determinate which of those techniques may bring better outcomes and improvements in ROM of hamstring muscle, the study also reveal that if those methods could be appropriate as a part of treatment of muscle injuries. The settings of a conduction of the study were as following booth techniques was applied to the two groups of participants. Measurement was taken before the application of techniques and straight away after application of those. Control group did not receive any stretching.
METHODS
This paper is regarding to research in which it critically review the already published journals on MET and static stretching and its influence on hamstring flexibility. There are many materials which follow the methods of study and whose results can deduce improvements which techniques from question put on the muscle. In the study, five main journals will form the basis of the review while there will be some backing using alternative journals. Different researches describes different research methods to reach conclusions, where many methods will be used to create the conclusion of this paper. In the research by O’Sullivan, Murray & Sainsbury (2009), the method carrying out a randomized study in two days, while assessing the flexibility of hamstring through measuring knee extension range motion (PKE ROM). The experimental sample was 18 previously inured individuals while the control groups were 18 uninjured persons. Both participants engaged in both dynamic and static stretches with results recorded and analyzed by Anova. In Biswas & Alagingi (2018), the method entailed an experimental design with 100 participants being assessed for hamstring flexibility. However, only 60 of the chosen an split into two groups, with each group subjected to either MET or static stretching and outcomes recorded. In an alternative research by Sharma Angusamy, Kalra, & Singh (2010), the researchers also employed experimental research, with both males and females being parts of the experiments. The participants were divided into two groups of 15 individuals each. This was similar to the methods used in the research by Waseem, Nuhmani & Ram (2010), with the only difference being that the participants in the latter were 20. The last was by Adkitte, Rane, Yeole, Nandi, & Gawali, (2016) in which the researchers used posttest randomized controlled experimental design.
DATA SOURCES
The following data were searched from following web sides – Pub-Med, Google Scholar, DOAJ-Directory of Open Access Journals and Oxford Academic Journals. The references list of relevant studies was scanned to find additional and appropriate trials.
LITERATURE REVIEW
MET alone
Muscle Energy Technique (MET) is a manual therapy which can be used by the gentle muscle contractions of the patient to bring relax and improve the length of the muscles and normalize joint motion. MET is mainly based on the reciprocal inhibition, there is a theory which explains that when you contract a muscle the opposing or reciprocal muscle must relax. MET is often applied to patients who suffer from muscle spasms. By the other hand Post-Isometric Relaxation (PIR) is based on lengthens a muscle as it relaxes right after a client contraction. This lengthens also relaxes muscle fibers. This can be used to treat chronic conditions to assist in resetting the muscle tone. Haitow , Liebenson, Murphy (2001) p.9-10
Static Stretching alone
Several studies shows that static stretching may reduce tension as also improve thw strength and power production, possibly for even an hour as following the stretch. Stretching exercises are appropriate and recommended for fitness and athletes as part of warming-up. Stretching prior to physical activity may also improve the plan to prevent injury and improve performance, despite a lack of research which would strongly support these effects. McNeal, Sands (2003) p.1
Comparison of booth techniques
The main article of this paper is entitled “Compare the effectiveness of static stretching and muscle energy technique on hamstring tightness among student population” as authored by Surojit Biswas and Nityal Kumar Alagingi (2018). In their comparison as to whether MET, the method entailed an experimental design with 100 participants being assessed for hamstring flexibility. However, only 60 of the chosen and split into two groups, with each group subjected to either MET or static stretching and outcomes recorded. It concluded that MET is better that static stretching, the authors concluded that both are essential at the same measures. The next four articles regarding to the literature review I chose because they directly address to my topic of study.
Ahmed et al. (2010) set yet, another premise for my research. I chose their article because it made a direct comparison of the two techniques: MET and static stretching. They compared the effectiveness of MET and static stretching in improving the flexibility of hamstring muscle in healthy male respondents. This research used the method and signed them to either MET or static stretching, just like the one done by Biswas and Nityal (2018). However, it was slightly different because other than the two groups, there was also the control group that was separate, making the groups used for test to be three. In this study, 40 participants were engaged, different from the 60 participants used by Biswas and Nityal (2018). Those study shown that there was a significant difference between the groups especially those exposed to MET and static stretching vs. control group. It concluded that both MET and static stretching is equally effective since there was no significant difference between the improvements in ROM between them
Adkitte et al. (2016) performed a study to examine the effect of MET on hamstring flexibility in Indian professional football players. The study used the methods of assessing the MET participants for a period of six days. It recruited thirsty Indian National Football Players and postisometric relaxation technique of MET was applying to them. The study found that there was a statistical significance in using MET on hamstring flexibility with the precession values (P <0.001). It revealed that MET increases hamstring flexibility among the Indian National Football Players and that it is god technique for preventing the injuries and improving their performance. The findings of the study conducted by Biswas & Alagingi (2018) agrees with this study as it also shown that MET and statistic stretching are more effective in improving flexibility of hamstrings. However, the method used by Biswas & Alagingi was different from that by Adkitte et al in the sense that they had no control group like the former. The article was also of use because it was thorough in terms of statistical analysis.
In a study entitled “Efficacy of muscle energy technique versus static stretching technique in increasing hamstring flexibility post burn contracture” Ahmed & Abdelkarim (2013), participants male adults aged 18 to 32 years. These people had no problems of decreased flexibility of the hamstring. He also divided them into three groups to perform static stretching, MET and another control group, which didn’t received any stretching technique. This is similar to the methods used by Ahmed et al. (2010). The conclusion was that both MET and static stretching was significant at some level. This is similar to the conclusion made by Biswas and Alangingi (2018). This article was significant in my study because it used a similar method like my main article.
The choice of participants is an important factor in the study. Such demographic factors as age, gender and health conditions at the time of experiment must be considered. As Abdelkarim (2013) chose males aged 18 to 32, Aundhekar et al. (2018) chose participants aged 50 and 80 years to study the effectiveness of MET and TENS. According to the topic of the study, the conclusion can more reliable with the participants aged 18 to 35 (Sharma et al., 2010). Another reliable age was chosen by Abd-Elkader et al. (2010) and this was age between 29 and 40. Age is of significance because the research seeks to understand the behavior of muscles which may undergo significant strain and relaxation. As the second important is, the number of participants chosen. Most researches choose samples of 30 or more participants. O’Sullivan et al. (2009); Ahmed et al. (2010); Biswas and Alangingi (2018); and Adkitte et al. (2016) are among the researchers who relied on 30 or more participants. Because the higher number of people can bring more reliable outcomes. However, study by El-Sobkey (2010) used smaller sample than the rest.
Most of the literature try to determine if MET or static stretching could be the best option for muscle relaxation. Some articles stand unsure yet, others have clear conclusions. Adkitte et al. (2016) concluded that MET was more reliable Abdel-aziem et al (2013). A study by Abdel-aziem et al (2013) is supported by the findings of the study by Adkitte et al. (2016). They all agree that stretching helps in improving the flexibility of hamstrings. For example, a study by Addel-aziem found that standing and supine stretches improve the flexibility of hamstring, and they both produce a higher improvement than DROM stretch during hamstring flexibility training while the study by Adkitte et al. (2016) concludes that MET increases hamstring flexibility among the Indian National Football Players and that it is suitable for preventing the injuries and improving their performance. However, they used different target populations but shown similar results. To support these findings, the comparative study by Dixit & Samal (2018) found that both MET and static stretching are effective in improving hamstring flexibility but MET is more appropriate than static stretching. D'Ambrogio (2012) also said that the MET has significantly better influence of hamstring flexibility.
Other articles are more detailed and look at wider aspects of exercise and stretching. A comparative study by Curry et al. (2009) examined the warming-up on selected measures of ROM and power in untrained women to find the permanent effects. The warming-up was involving light aerobic activity, dynamic stretching, and static stretching. The study found that dynamic stretching was better in increasing of performance on power as compared to static stretching. These findings agree with the findings from a study by Sehgal et al. (2016) which found that participants assigned to MET technique got significant improvement in ROM in comparison to static stretching where outcomes was weak. Also, Ahmed (2011) both MET and dynamic stretching improve hamstring flexibility in healthy adults.
These findings agree with the findings from a study conducted by Harper (2011) whose purpose was to evaluate the effects of acute stretching on 12 competitive performance of gymnasts of the split jump. Flight time, vertical displacement, and degree of split measures were used to evaluate the performance. The findings of the study reveal that there is no significant difference between the three stretching protocols for any of the measures. However, the three stretching protocols have a significant difference when compared to no stretching and they can be used even during warm-ups by sportsmen and women. But according to Odunaiya et al. (2005) stretching tight hamstrings for any duration can significantly increase sustained flexibility. But Kilstler et al. (2010) argue that static stretching in the warm-up protocol is not suitable under strict terms of performance as it appears harmful to an individual. Dave et al. (2019) support these findings by arguing that combined protocol can be used to prevent injuries and improve bio motor abilities in football players .
A systematic literature review by Decoster et al. (2005) summarized the studies by saying that hamstring stretching increases ROM depending of durations, position, and stretching techniques. But Reddy & Metgud (2004) argue that conventional therapy, as well as the use of MET along with Conventional therapy, are both equally effective. Similarly, Worrell et al. (19994) add that there is no significant difference when using static stretching in improving hamstring muscle flexibility. These findings are supported by Yamaguchi & Ishii (2005). Also, Young & Elliott (2001) support the findings that static stretching produced a nonsignificant decrease in concentric explosive muscle performance.
Finally, some of the researches focused on injured participants or uninjured participants as their subjects. This study are focusing on uninjured athletes, making the conclusion to rely more on articles which focus on this group. Jonhagen et al. (1994); Worrell et al (1991) chose both injured and uninjured participants to determine the effectiveness of MET. However, most of the articles, including O’Sullivan et al. (2009); Ahmed et al. (2010); Biswas and Alangingi (2018); and Adkitte et al. (2016) only considered healthy participants, making their conclusions more appropriate to this study.
Methods of Application
The articles review different methods of application of choosen techniques. In the research by Biswas & Alagingi (2018), the testing of the intervention as MET or static stretching involve different activities. These included active knee extension, Sit and Reach test, static stretching group, and Muscle energy technique. Active knee stretch was sued to test ROM. It involved two therapists holding the limb, with the primary investigator taking the measurement. One leg was to be tested while the other one used for control. The participant laid his spine on a couch with the control leg strapped to the plinth. The researcher position the leg for testing in a position of 90 degrees with knee and hip flexed. The participant was requested to stretch his knee to the maximum until there was a mild stretch on the posterior of the knee. This was done three times.
To test MET, the participant still laid his spine on the couch. The therapist played with the leg by positioning it in a raised position while hip flexed. The knee was in the extension position while ankles were neutral. This was to happen for as long as the patient was not feeling pain or discomfort. This position stayed put for 30 seconds. The procedure was repeated four times with 30 seconds sessions. The type of stretch is to take place for three to four weeks. The same procedure was applied by Adkitte, Rane, Yeole, Nandi, & Gawali, (2016).
The procedure above procedure is almost similar to the one done by Waseem, Nuhmani, & Ram (2010), in which the popliteal angle was measured to determine the tightness of the hamstring. To test the MET, the participant was placed in a position in which the knee did not show any strain. Afterward, there wasMET is the most efficient technique to improve muscle hamstring flexibility.
an elicitation moderate hamstring contraction for 5 seconds. This is different from the previous procedure in which the stretch or relaxation was done for 30 seconds. However, both were observed repeatedly for four times. The procedure set by Biswas & Alagingi (2018) tends to be more reliable because it is comprehensive and goes for 30 seconds instead of 5 seconds.
Methods of Measure
The instruments of measures were of very important for the studies. Typically, many of the measurements considered the degree of stretching of the knee as it was exposed to strain or relaxation. Plastic goniometer marked off in 90 degrees was the most reliable instrument as used by Abdel-aziem, Draz, Mosaad, & Abdelraouf, (2013); Biswas & Alagingi (2018); Curry, Chengkalath, Crouch, Romance, & Manns, (2009). However, a unique instrument as 8 camera Nexus 1.5 motion capture was cited by Harper (2011). This camera was used alongside fifteen reflective markers that were placed at the strategic points of the joints.
Most of these procedures produced statistical data that needed software for their interpretation. In the experiment by Adkitte, Rane, Yeole, Nandi, & Gawali (2016) employed the paired t-test as the main tool for statistical analysis. This instrument measured the improvement in the presession values and postsession values. The results indicated a presession value of (P < 0.001) and postsession values of (P < 0.001). The paired t-test is a complex method that is not very popular in this investigation as many other articles relied on SPSS software to analyze the outcome, as witnessed in the inquiry by Waseem, Nuhmani, & Ram (2010); Biswas & Alagingi (2018). In summary, a plastic goniometer was appropriate for the measurement of knee angles, while SPSS was the appropriate instrument for statistical analysis.
Population
The population of the study was of significance because the focus of the research was young males. Articles that recruited male participants have more weight than those that employed female participants. Among the participants as well, the most appropriate ones are the ones within the youthful age. In the study by Ahmed & Abdelkarim (2013), the population sampled was thirty male adults aged 18 to 32 years. This population was ideal, just like the one chosen by Biswas & Alagingi (2018), whose participants aged between 18 to 22 years old. Most of the researches that are considered reliable also relied on the young population, aged between 18 to 35 years. It is more so considering other studies like Sharma et al., 2010, which used the sample of male participants aged 18 to 35. Anther sample population, which was a little bit different, but still within the threshold was in the article by Abd-Elkader et al. (2010) in which the participants were aged 29 to 40 years. The totally different population was recorded in the study by Aundhekar et al. (2018), who chose participants aged 50 and 80 years. The conclusion from this article cannot be reliable in our studies because the population selected for surveys does not adequately reflect the one we are interested in.
Hence, the best article for this literature review turned out to be Biswas & Alagingi (2018), which used the most appropriate population and the most desirable techniques and instruments. This researcher employed the most popular SPSS software to analyze the statistical outcomes. The article also cites the use of goniometer for measuring the angle of knee bending or lack of it. Plastic goniometer emerges as the most reliable instrument for the measurements in such types of experiments. The conclusion of this study can be replicated in another study because it followed a reliable procedure and used appropriate instruments. The population was also good because it was 18 to 22 years, which is within the age bracket of young males.
FINDINGS
The studies presented several results. For example, some studies found that stretching increased the joint ROM significantly. It also forces the muscle to produce peak torque angle or maximal torque. Others found that that reduced flexibility of muscles decrease functionality and also may lead to overuse injury. It was also revealed that hamstring stretching increases ROM regardless of durations, position, and stretching techniques. Others found that hamstring flexibility may be increased by a warm-up and static stretching and that even did not reach statistical significance. However, the studies found that static stretching and MET are equally effective but agree that MET is more effective in increasing muscle extensibility that improve a ROM. It was found to lengthen the hamstring muscle and stimulate muscle contraction after stretch.
DISCUSSION
Flexibility is experienced when there is a total range of movement (ROM) around the joint. The ROM depends on the structure of the connective tissues around the joints. Therefore, muscle flexibility improve ROM. Studies have revealed that structural changes in the length of the muscle put affection on flexibility (Biswas & Alagingi, 2018).
Also, when the angle of the joint is gradually extended, it leads the muscle to produce peak torque angle or maximal torque. As a consequence, the changes in muscle length are inferred. Biomechanical performance of joint also depends of the posture of the body as well as other impacts regarding that. Therefore, the findings agree with other results of the studies conducted previously which revealed that reduced flexibility of muscles decrease functional levels and also lead to overuse injury (Biswas & Alagingi, 2018).
Many studies used in the literature review have analyzed and examined couple different types of stretching and their impact on hamstring injury. The results from these studies may be divided into training effects or acute effects. Acute effects regarding to immediate effect produced by the stretching while training effects depends of long period of time. The studies also involved different muscles groups in examination as well as different target populations as some used professional footballers (Adkitte et al., 2016) and others used basketball players (Nunes et al., 2012) and athletes (Sudhakar & Kumar, 2016). These variations make interpretation and recommendations quite difficult. But any way it is important to consider these factors when making conclusions and recommendations.
Stretching is commonly used in improving of the muscle length and to cause changes that prevent before possible biomechanical alterations. For instance, there are several programs of stretching that are commonly used to restore muscle strength and flexibility. Studies have shown that there are many effective programs of stretching that can be used to increase joint ROM. However, the effectiveness of stretching depends on how frequent they are used to restore muscle flexibility. Studies have argued that static stretching is the commonly used technique of stretching to restore muscle flexibility and joint ROM. The technique is not only controlled but is also slow. It is used to induce flexibility, especially in sportsmen and women. MET is an alternative technique of stretching to restore flexibility. It voluntarily contract the muscles in a specific direction and controlled position against therapist pressure. Aundhekar et al. (2018) demonstrated that MET is more efficient in increasing muscle extensibility due to muscles’ elastic changes that improve the joint ROM.
When comparing the immediate effects of MET and active dynamic stretching, Dixit & Samal (2018) found that subjects who received the MET technique, especially those who had bilateral hamstring tightness showed a significant improvement. Also, the findings revealed that those exposed to passive stretching demonstrated significant improvement as compared to those subjects who performed active stretching as far as flexibility is concerned. Yamaguchi & Ishii (2005) reported that MET increase the length of the muscle and muscle contraction after stretch stimulation. They also observed that reciprocal innervation mechanism characterizes active stretching and it is applied in helping to relax antagonist muscle contraction.
Sharma et al (2010) also explain MET as a method of manipulation of soft tissues in a manner that is directed and controlled by the therapist. It is also initiated by the patient sometimes. This manipulation of soft tissues is used to reduce pain and enhance the functionality of muscles. The authors also found that the technique is widely used especially when it comes to the treatment of somatic dysfunctions of the muscles and hamstring. They also describe the benefits which MET could brought. These benefits include the ability to make the muscle relaxed and lengthening of the shortened muscle.
The reviewed studies have shown that there are different types of MET techniques as noted before. Sudhakar & Kumar (2016) focus on static stretching and set up that it is a type of stretching exercise where muscle getting increased length with low force and long duration takes place – usually 30 seconds. The technique results in both increased length of the tissue and relaxation. It also reduces stiffness in the muscles and significantly reduces the risks of extended muscle strain injuries. It is also important to note that the technique is appropriate for all patients with different conditions. Ahmed et al (2010) compared the effects of MET and static stretching in treating hamstrings. The results demonstrated that there was no significant difference between those two techniques as MET was compared to static stretching in treating of hamstring.
Most studies have found that stretching increasing the joint ROM significantly. For instance, hip or knee ROM can be used to activate hamstring length changes. By the other way, the individual may just have an increased stretching tolerance without ROM increasing muscle length (decreased tension) (Worrell et al., 1991; Worrell et al., 1994). MET and static stretching techniques have proven to be effective in increasing ROM and alleviating hamstrings. However, MET is the most effective technique, because with static stretching most studies have demonstrated that 10 seconds are enough to increase flexibility but there is no significant improvement after 2 to 4 repetitions (Young, 2007; Yamaguchi & Ishii, 2005; Sehgal et al., 2016). It is also important to note that there is a significant improvement, as far as increasing ROM is concerned, when contraction of the muscle is done before stretching. Hold-relax technique has proven to be very good especially in supporting post-isometric relaxation stretching. However, this is not clear that the muscle flexibility increase immediately before stretching and contraction.
However, unfortunately, static stretching as one of the components of warm-up before the real performance has shown that it can have a relevant effect on muscle strength as well as performance and jumping and running. Acute static stretching results in loss of strength which is commonly called as “stretch-induced strength loss” (Papadopoulos et al., 2005; Odunaiya et al., 2005; McMillan et al., 2006; Kistler et al., 2010). Some studies have suggested that it is not very clear to state the causes of induced strength loss but others have proved that mechanical and neural factors are the leading causes of induced strength loss.
Reviewed literature states that hamstring stretching increases ROM depending of durations, position, and stretching techniques (Decoster et al., 2005). However, De Weijer et al. (2003) observed that an increase in hamstring length is sustainable after stretching but any warming-up before performance is not significant as far as increasing the effectiveness of static hamstring stretching is concerned.
But Reddy & Metgud (2004) argue that conventional therapy, as well as the use of MET along with Conventional therapy, are both equally effective. Similarly, Worrell et al. (19994) add that there is no significant difference when using static stretching or proprioceptive neuromuscular facilitation stretching techniques in improving hamstring muscle flexibility and that static stretching produces a nonsignificant decrease in concentric explosive muscle performance (Yamaguchi & Ishii; 2005; Young & Elliott, 2001).
As far as the effects of static stretching after a dynamic warm-up on power, agility, and speed are involved, some studies found that static stretching after a dynamic warm-up before performance does not have any significant (Bishop & Middleton, 2013). Others shown that there is a strong relationship between a static stretching program and a decreased incidence of musculotendinous strains (Cross & Worrell, 1999). The application of comprehensive exercises is important in reducing WRMD incidences (Abd-Elkader et al., 2010). However, some studies have found that hamstring flexibility is significantly increased by a warm-up and static stretching and not dynamic stretching which even did not get statistical significance, patients with reduced flexibility after the injury record greater effect of warm-up and static stretching on flexibility (O’Sullivan et al., 2009).
When efficiency between MET and static stretching in improving the flexibility of hamstring muscle is considered. The findings of the study revealed that there was a significant difference between the groups especially those who received the MET and static stretching vs. control group. By the other hand, MET and static stretching are equally effective since there was no significant difference in achieved ROM between them (Ahmed et al., 2010). But during the examining of the effects of MET in increasing ROM (range of motion) and strength of Glenohumeral Internal Rotator in sportsmen and women suffering from Glenohumeral Internal Rotation Deficit (GIRD) Sehgal et al., found that subjects assigned to MET recorded a significant improvement in ROM and not those assigned to static stretching. They concluded that MET is effective in treatment and for increasing ROM in athletes with GIRD.
In the comparison of MET and TENS in reducing pain and increase ROM in the hip, some studies have found that both MET and TENS were effective in increasing ROM and reducing pain but MET was more effective (Aundhekar et al., 2018). Other studies have demonstrated that there is a statistical significance in using MET on hamstring flexibility (Adkitte et al., 2016). Also, MET increases hamstring flexibility among the Indian National Football Players and that it is suitable for preventing injuries and improving their performance. Biswas & Alagingi (2018) agree with this study as it found that MET and statistic stretching are more effective in improving the flexibility of hamstrings.
The review considered different aspects of research like the methods of study, the population of choice and the instruments used in the studies. Different articles evaluated different techniques depending of their relevance to the study. They set up that the most reliable method for carrying the studies was active knee extension, Sit and Reach test, static stretching group, and Muscle energy technique. The most reliable procedure was that which required lying spine on a couch while the therapist moved the leg in different angles while the stretch was being recorded as it was presented in the research by Biswas & Alagingi (2018). This method was found to be appropriate because it was comprehensive and gave results in many aspects of muscle stretching. In measure, plastic goniometer seems as the best instrument of the study because it was easy to use, and it was also popular in many researches.
It is also important to indicate that the appropriate population of study was the ones consisting of males aged between 18 - 35 years. This was because the topic addressed the issue of flexibility among the young male population.
CONCLUSION
Both static stretching technique and muscle energy technique (MET) are mostly used to release the pain. However, MET is an advanced technique as compared to static stretching technique. For example, MET include isometric muscle contraction which is later followed by stretching. However, it is important to note that we cannot see how conventional treatment contributes to treatment of the hamstring muscle. Studies that have compared these two techniques have proved that they are both effective even when these studies used asymptomatic and symptomatic populations.
Some studies have guessed about the neurological mechanisms which produces the ROM of the joint after application of the MET. However, these studies did not produce enough evidence to validate that thesis. Also, there is confusion in mechanisms responsible for improving the flexibility of muscles after static stretching, MET or hold-relax stretching. However, these results may be caused because of neurophysiological or biomedical changes. It may also be due to tolerance stretching by the muscle. It makes a sense therefore, to claim that MET produces significant changes immediately in the hamstring muscle flexibility even though there is little evidence that changes become from tolerance to stretch or mechanical property changes of the muscle.
Some studies by Ahmed et al. (2010) and Adkitte et al. (2016) talked about the use of post isometric relaxation techniques in treating patients with hamstring injuries. Form these studies, it is clar that post isometric relaxation technique also leads to a significant improvement in muscle extensibility. They also compared the effect of MET and static stretching and also found that MET is more effective in increasing the length of the hamstring muscle. Some of the effectiveness include an, neurophysiological changes, and the biomechanical event that result in increased flexibility. Also when compared to ultrasound therapy and dynamic stretching, MET was more effective in patients suffering from hamstring tightness.
Another reason why MET was found to be more effective than static stretching in treating patients with hamstring injury is because MET involve active isometric muscle contraction following a stretch that is performed against the resistance of the therapist or the patient. This stretching also include passive stretching. Therefore, an active or moderate pressure should become after passive stretching of the isometric muscle contraction of hamstring against the resistance of a therapist for MET to be more effective. This exercise should be followed by patients conducting active contractions in order to improve the ROM and length of tissues.
Studies comparing the MET and post-test torque demonstrate that MET significantly improves the passive stretch of the hamstring but the application of pre-torque and post-torque did not.
Muscle physiology involves that. It is important to note that MET should be applied more often if patient and therapist want to achieve any changes in soft tissues. Future studies can use different populations in considering the effects of MET and static stretching on patients with hamstring injury and assign them to an equal number of applications of MET and static stretching, similar durations, and similar conditions while record and compare the results. The present study examined different researches that used different populations and conditions, for example, professional footballers, basketball players, other athletes, and women among others. This approach will help to compare the effects of MET and static stretching in more details when similar approaches are used on populations suffering from hamstring injuries.
It is also recommended that clinicians choose a technique or an intervention for improving muscle tension appropriately depending on the genesis of the tightness. For example, stretching is based on increasing muscle length thereby increasing the distance between the insertion and the origin of the muscle. The literature has frequently described several stretching techniques regarding to hamstring; so MET, and static, and also dynamic stretching techniques among others. Static stretching is the most common and traditional stretching technique and can be performed passively or actively by the therapist or the subject.
Therefore, regarding to the findings of this study, MET can be selected over static stretching for treating affected hamstring. And when the two techniques were compared as a conventional therapy, they became more effective. This reality strongly suggests that a practitioner has wide number of strengthening technique to use to reach maximum benefits as far as treating patients with hamstring injuries is involved. However, this study strongly recommends the use of MET – which is a great stretching technique used with other conventional exercises in treating patients with hamstring injuries.
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