Effects of Superficial and Deep Thermotherapy with Hot-pack and Ultrasound on Flexibility on Hamstring Muscles

Ⅰ. Introduction

According to statistical data of Ministry of Health & Welfare and Korea Centers for Disease Control and Prevention, Koreans spent average 7.5 hours to sit. Persons in 19-29 years old are the longest average 8.7 hours per day, persons in 30-39 years old are 7.6 hours and persons in 40-49 years old spent 7.3 hours to sit(Statistics, 2014). Most of the moderns have been spent sedentary life style in front of desk or on the chairs, so that their hamstring muscles are shorted commonly and the shortness of hamstring muscles are caused to some problems in functional activities(Kisner and Colny, 2012). The tightness of hamstring muscles is caused on a posterior pelvic tilt and decreases lumber lordosis, resulting on low back pain(Gopi et al, 2014). Hamstring muscles primarily control the forward swing of the leg during terminal swing and also provide posterior support to the knee capsule when the knee is extended during stance phase(Kisner and Colby, 2012). Therefore, the shortness of hamstring muscles is to be main problem in personal healthy habits and rehabilitation settings.

To improve the shortness of hamstring muscles, previous studies have been conducted the stretching exercise on the lower extremity. Stretching exercise is a process whereby the overall functioning of a person may be improved by applying stretching techniques selectively to some muscles and joints but allowing limitation of motion to develop in other muscles or joints(Kisner and Colny, 2012). Several author suggested that 30-s duration of stretching one of three times a day is effective for increasing muscle flexibility(Marques et al, 2009).

In rehabilitation settings, thermotherapy is used primarily to control pain, to increase soft tissue extensibility and circulation, and to accelerate healing(Cameron, 2013). Force and time of stretching should be decreased as the temperature of muscle increases(Kisner and Colby, 2012). When soft tissue is heated before stretching, the soft tissue retains its length after removing the stretching force(Cameron, 2013).

Another most common thermothery modality is hot-packs, which conduct superficial heating agent. Hot-packs are usually made of bentonite, a hydrophilic silicate gel, covered with canvas and these types of hot-packs are made in various sizes and shapes designed to fit different areas of the body(Cameron, 2013). Hot-pack is often used as the prior therapeutic modality of muscle stretching(Yoshida et al, 2015). Before stretching, heat application to the shortness of hamstring muscles could result in greater increase in hamstring extensibility( Lee, 2008; Funk et al, 2001).

Therapeutic ultrasound is used to treat a variety of condition and it is often used as a thermal modality when treating soft tissue injuries(David et al, 1998). Therapeutic ultrasound has two important physical effects, thermal effect which is a increase of temperature on transmitted and boundary tissues, and nonthermal effects which is acoustic streaming, cavitation, and altering cell membrane permeability(Cameron, 2013). Persons with knee pain have relieved their pain after applying the therapeutic ultrasound(Nuri, 2008). Static stretching exercise for 30 seconds followed by therapeutic ultrasound showed a significant increase in the flexibility of hamstring muscles(Emad, 2014).

Although previous studies have been demonstrated the effectiveness of hot-pack and therapeutic ultrasound on improving on flexibility of hamstrings tightness, two modalities of thermotherapy have the different physical effects in human tissues, but there is insufficient of the comparing the effect of the two modialities of thermotherapy on the flexibility of hamstrings tightness. The purpose of this study was to compare the effectiveness of thermotherapy with hot-pack and therapeutic ultrasound on the tightness of hamstring muscles before in individuals with hamstring tightness.

Ⅱ. Methods

Ⅲ. Results

Ⅳ. Discussion

Hamstring shortening can easily happen because modern people spend most of their daily livings to sit in a chair. Due to that the hamstrings tightness generate a posterior pelvic tilt and decreases lumber lordosis, which can result in low back pain. Lack of hamstring muscles extensibility decreases pelvic mobility, could also cause a various of functional disabilities such as abnormal gait, back pain (Gopi et al, 2014)

Various stretching exercises for the hamstring shortening was studied and also study about pre-treatment for stretching exercises was performed. Generally, hot-pack and therapeutic ultrasound were used to assist as warm-up period on stretching exercises and study is also conducted to prove it, but these study were done independently, study that comparing two pre-treatment is insufficient.

This study applied hot-pack and therapeutic ultrasound as the warm-up on hamstring stretching about hamstring shortening and was conducted to suggest better warm-up method by comparing hamstring extensibility through the hip joint flexion test. Hamstring shortening is a case that appeal the tightness of posterior femur when bent forward at the waist in standng position and shows a positive reaction in the hamstring contracture test(Magee, 2008). Therefore, this study measured hip joint flexion angel through the straight leg raise(SLR) test before and after experiment to observe the changeable amount of hamstring stretching.

The result of this study ultrasound group was the most effective among the three groups to increase the hamstring extensibility. The group that applied ultrasound as pre-treatment appeared the largest increase of hip joint flexion angle according to before and after experiment and the group that applied hot pack as pre-treatment showed the second largest variation. On the other hand, group that not peformed any warm-up showed the lowest value variation. Thus, thermotherapy was certain effect to pre-treatment on hamstring stretching exercise, deep heat therapy can be considered that there is a larger effect than superficial heat therapy.

Limitations of this study rather difficult to generalize the results of the study because the participants consisted of three groups, each group consisting of 9-10 people so the small number of participants. Also, It may not be objective by the number of variables because this study compared hamstring extensibility before and after experiment using only inclinometer without other measure equipment. The site of application of hot-pack and therapeutic ultrasound may be some errors in the application site so it is considered to be able to affect the study results. As this study performed stretching exercise, it may be not objective that did not considered the individual's exercise capacity. Therefore future study should be conducted suggested that the study complements these limitations.

Ⅴ. Conclusion

This study was participated by twenty-eight persons with tightness of hamstring muscles and participants were randomly assigned to one of the following groups: stretching group, hot-pack group, ultrasound group. After examining flexibility of dominant side hamstring, each group were performed stretching, stretching applied after hot-pack, stretching applied after ultrasound and then observe the influence on the extensibility of the hamstring. Furthermore study was made to suggest to more effective warm-up of hamstring stretching exercise. The group that performed stretching exercise after apply the hot pack showed tendency to increase the extensibility than group that applied stretching exercise, the group that performed stretching exercise after apply the ultrasound showed tendency to increase the extensibility than group that performed stretching exercise after apply the hot pack. This results support the effectiveness of heat therapy as a pre-treatment on stretching exercise and it will be able to provide useful data for future study.

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