Modulation of Muscle Pain and Tissue Compliance
July 26, 2006
Modulation of Muscle Pain and Tissue Compliance by Means of the ROM Device: [Intracell Stick]: Pilot Study / DOD
By Andrew S. Bonci
Muscles that lack flexibility exhibit the following features. They lack compliance and resiliency and are more susceptible to injury and pain. Flexibility training is intended to maintain an adequate level of muscle suppleness, elasticity, strength and endurance (1-3). This is believed to be achieved through unimpeded blood flow, nutrient delivery and optimization of the length-tension relationship of muscle (1-4). Certainly, flexibility training can enhance a soldier’s battlefield performance and his survival through prevention of injury and optimizing his muscle fitness.
Deep muscle massage by application of the ROM Device has been suggested as an adjunct to flexibility training in the military (2). In addition, the ROM Device has demonstrated itself to be effective in modulating muscle pain following heavy training. If these benefits can be established, then it is conceivable that the ROM Device can optimize the battlefield performance of soldiers while conveying the benefits of injury prevention.
This study is intended to investigate the effectiveness the ROM Device has on modulating muscle flexibility and muscle pain. This will be done by performing pre- and post-treatment measures of tissue compliance and pressure threshold. Data will be collected from a representative sample of the military. Analysis will be performed by the paired t-test statistic in groupings such as age, rank, duty assignment, etc.
The results of this study will be presented with a view toward enhancing general flexibility and muscular performance in military personnel. In addition, suggestions regarding injury prevention, recovery from muscle soreness and the management of muscle pain will be discussed as a means toward cost containment.
Muscle flexibility is an important component of physical fitness (I -4). Developing and maintaining an adequate level of flexibility is vital to every soldier’s fitness program (1,2). Flexibility conveys a number of benefits to soldiers which include, but are not limited to the enhancement of lifting and loading capabilities, climbing and repelling skills, running and marching proficiency and parachuting (1,2). In addition, insulation from musculoskeletal injuries and accelerated recovery from these injuries are very attractive benefits accompanying gains in flexibility (1-7). When a soldier is flexible enough to perform optimally and free of injury, then operations can be executed efficiently and cost effectively without significant loss of man power.
Muscle flexibility can be defined as a function of compliance and tone. Compliance relates to a tissue’s ability to be bent, twisted, elongated or compressed (8-13). A muscle that has a high degree of compliance can be said to be flexible by virtue of the ease with which it can be bent, twisted, elongated or compressed. A stiff, rigid or inflexible muscle would have a low degree of compliance. It follows that compliant muscles are more flexible and less prone to injury. An interesting method of measuring a tissue’s compliance is with a tissue compliance meter (TCM). A TCM measures the depth of penetration of a I centimeter squared rubber tip with respect to the force required for that penetration (8-13). The mathematical relationship of the depth of penetration (D) divided by the force needed to produce that penetration (F) yields what is called the flexibility coefficient (f). The flexibility coefficient (14) is given as follows: f =D/F.
Muscle tone is the characteristic resiliency or resistance to stretch in the relaxed muscle (3,4). Muscle tone is maintained through reflex activity of the nervous system and is not believed to be a property of the isolated muscle. However, it can be argued that muscle tone has at least two components- (1) active – due to partial contraction of the muscle through the nervous system; and (2) passive – due to the natural elasticity or turgor of muscular and connective tissues, which is independent of nervous innervation (4). As a muscle increases in its degree of tone it becomes tighter and less compliant (8-13). This is referred to as hypertonicity and can be measured with the TCM and quantified with the fle3dbility coefficient. However, normative data relative to muscle tone are difficult to find.
Muscle tone that is mediated by the active components is beneficial in that it keeps the muscle in a state of constant readiness (3). Normal muscle tone keeps the muscle set at the proper length and tension for quick and powerful contractions (3,4,15). Problems arise when the muscle is either hypotonic (flaccid) or hypertonic (tight). When in the flaccid state, the muscle loses its ability to be an effective, elastic shock absorber. This can result in joint and ligamentous injuries since potentially damaging forces are immediately shifted to these structures without the benefit of the elastic attenuation provided by the muscle.
When in an abnormally tight state, the muscle becomes hard and less compliant (8-13). The hardness of increased tone comes from the muscle squeezing itself (3). This squeezing action raises the intramuscular pressure which can partially or completely block the muscle’s blood flow depending on the degree of increased tone (3). This reduction of blood flow impedes the removal of metabolic wastes and the delivery of nutrients and oxygen (3). It is not surprising that strength production and endurance in these stiff, non-compliant muscles suffer.
Muscular endurance is more profoundly affected by reduced blood flow and the concomitant reduction in tissue oxygen tension (3,4). Local aerobic metabolism in the hypertonic muscles may, therefore, be limited by the reduced presence of oxygen. Attenuated muscle strength of a hypertonic muscle may be mediated by factors other than local oxygen tension. Muscles that exhibit hypertonus are shorter and tighter. This process of shortening forces the muscle to operate outside of its optimal length-tension relationship. The length-tension relationship states that the tension or strength a muscle can generate is dependent on its length (3,4,15). Maximal tension is generated when the muscle is at its “normal” resting length. As the muscle leaves its normal resting length (i.e., gets longer or shorter), its ability to generate force drops off quickly (3,4,15). In the case of hypertonicity or inflexibility, the muscle is shorter than its “normal” resting length. This “shortness” compromises the muscle’s ability to generate strength.
Another interesting feature of muscle is the length-velocity relationship. The lengthvelocity relationship is as follows: The velocity of contraction is dependent on the length of the muscle (3,4,15). As a muscle shortens, the speed with which it continues to shorten is quickly reduced (3,4,15). Therefore, a muscle that is tight and shorter than “normal” resting length will have a limited ability to contract with any rapidity. It becomes clear how important flexibility training is to endurance (intramuscular pressure and blood flow), strength (length-tension relationship) and speed/agility (length-velocity relationship).
Tight muscles that lack in compliance have an increased susceptibility to pain and injury (1-13,16,17). These muscles lose their resiliency and elasticity and are likely to sustain tears during sudden tensile loading. Muscle injuries such as these can severely limit the muscle’s ability to perform optimally until complete healing has occurred. This healing process is often stalled by reactive muscle spasm, which is itself a condition of increased tone that is mediated by the nervous system and the effects of injury (5-7,16,17). The major feature of muscle spasm is ischemia that results in muscle pain (5-7,16,17). Ischemia is a state of limited blood flow and oxygen delivery that is caused by the muscle squeezing off its own blood supply.
The TCM can quantify the degree of tone or flexibility of a muscle while a pressure threshold meter (PTM) can quantify a muscle’s sensitivity to pain (8-13,18-20). The PTM measures the minimum amount of force needed to induce pain (threshold). If a muscle has increased tone and is mildly ischemic (i.e., low oxygen tension, metabolic waste build up), then its threshold for pain will be reduced. When the tone is restored to normal and the muscle is more compliant, then its pain threshold will be increased.
The question arises as to what will modulate muscle tissue compliance and pain. Stretching and deep muscle massage are believed to enhance flexibility (1-7). Training to enhance flexibility is imperative for muscular performance and injury prevention (1,2). Although the exact mechanisms for this contention is not clearly understood, it appears to be related to adequate blood flow and the elastic properties of compliant muscle tissue. Stretching and deep muscle massage may help to augment both the active and passive components of muscle tone. Resetting the tone of the active components and lengthening the passive components of the muscle and its relationship to tissue compliance and muscle pain is worthy of further study in light of flexibility training and deep muscle massage.
Recently, a proposed addendum to Chapter 4 of the Army Physical Fitness Manual was made regarding P.E.T. Massage. P.E.T. Massage was introduced relative to the ROM Device which is a tool that can convey the benefits of deep muscle massage. The ROM Device is a non-motorized tool that measures 24 inches in length with 14, 1 inch independent spindles. These spindles freely spin around a semi-rigid plastic core. Handles are provided at both ends for ease of use. The ROM Device is intended to allow the individual soldier to apply deep tissue or P.E.T. Massage to himself
P.E.T. Massage is an acronym which stands for Prevention, Endurance and Treatment. The section from the proposed addendum to Chapter 4 of the Army Physical Fitness Manual is reproduced here for convenience.
ROM exercises are essential in the Prevention, Endurance and Treatment [PET] of the muscular system and are described as follows:
When the soldier has been inactive for a period of time the muscles become less pliable. Metabolic waste products may become trapped in the muscles which further reduces fluidity. A sudden loading of these “cool” muscle bundles can cause extensive stretching of the muscle fibers. This overstretch or muscular strain adversely effects musculoskeletal flexibility. ROM exercises work to dilate blood vessels, extricate trapped metabolites, increase circulation and prepare the muscle for loading. A healthy oxygen-rich muscle will stretch naturally with more flexibility. ROM exercises can prevent nagging to incapacitating sprains, strains and muscle tears.
Endurance is one of the three (3) basic dimensions of physical fitness. Low intensity exercise is provided by aerobic metabolism. Intense exercise uses energy more quickly and anaerobic metabolism is recruited to fulfill the additional energy requirement. A product of this metabolism is lactic acid which builds in the muscles and increasingly interferes with normal muscle function thereby contributing to fatigue. It is important to utilize the ROM exercises during intense physical activity to help replenish the energy requirement and to help in the removal of metabolic waste products. This procedure may increase the soldiers’ endurance and muscular enhancement.
Post physical activity is sometimes accompanied by muscular soreness and stiffness. This is especially true if the body recruited anaerobic metabolism during workout. Recovery time to specific muscles is greatly reduced when stripping massage is applied with the ROM device. Muscle spasms, or an unconscious contracture of muscle tissue, may interrupt or follow strenuous activity. All periods of strenuous activity should conclude with the eight (8) minute regime using the ROM device.
The issue of specificity needs to be addressed. Traditional flexibility exercises are nonspecific in nature. Since many of the muscles of the body are multi-joint muscles (i.e., they cross more than one joint), difficulty arises in insuring flexibility of a whole muscle (21). Uniform stretching of muscles in vivo is difficult because muscles are typically shortened across one joint while simultaneously lengthened across another. This is a very nonspecific approach to stretching. The ROM Device appears to solve this problem. The ROM Device can be used to locate indurated and tender areas where the muscle is shortened. Once found, specific localization and elimination of segmentally shortened muscle can be achieved. Traditional stretching techniques do not share the same level of specificity as that outlined in the ROM exercises described in the proposed addendum to Chapter 4 of the Army Physical Fitness Manual.
Can the deep muscle massaging action of the ROM Device increase muscle tissue compliance and attenuate muscle pain?
MATERIAL AND METHODS
This pilot study is concerned with the effects of deep muscle massage as an integral part of flexibility training on the modulation of muscle tissue compliance and muscle pain. Due to time -constraints, this study will focus its attention on the immediate effects the ROM Device has on muscle compliance and pain.
The materials needed for this study will include a tissue compliance meter (TCM) and a pressure threshold meter (PTM).
The study sample will be representative of all the branches of the military, its hierarchy and duty assignments. Subjects with a history of knee and back pain will be the main inclusion criteria for this study. Tight muscles of the quadriceps, particularly the vastus medialis, have been cited as a cause of knee pain (17). Tight muscles of the back, especially the quadratus lumborum, have been cited as a cause of back pain (I 7). For these reasons, the vastus medialis and the quadratus lumborum muscles will be examined for this study. Tissue compliance studies will be conducted on the vastus medialis and pressure threshold studies will be conducted on the quadratus lumborum.
This pilot study is designed to look at three specific and narrowly defined issues. First, it is important to establish whether or not the ROM Device can modulate tissue compliance. If it does, it is also important to know if it is significantly better at modulating tissue compliance than is traditional stretching. Second, it is important to illuminate the ROM Device’s ability to modulate pain. Third, can the ROM Device attenuate the effects of delayed onset muscle soreness.
The first part of this study will specifically look at muscle tissue compliance of the vastus medialis muscles. The study design will utilize pre- and post-test measures on each subject. This will allow each subject to serve as his own control. Pre-test tissue compliance measures will be taken on one of the vastus medialis muscles. This will be followed by 20 progressively deeper passes of the ROM Device over the tested vastus medialis. Following this intervention with the ROM Device, a period of 2 minutes will be allowed to elapse during which time the subject can relax. At the end of the 2 minute period, a post-test tissue compliance reading will be taken at the identical pre-test location.
The contralateral vastus medialis muscle of the same subjects will be tested for changes in tissue compliance with the application of traditional stretching maneuvers. Pre-test tissue compliance measures will be taken on the companion vastus medialis muscle. This will be followed by stretching with the knee in nfildly forced flexion for thirty seconds. Following this traditional stretch a period of 2 minutes will be allowed to elapse during which time the subject can relax. At the end of the 2 minute period, a post-test. tissue compliance reading will be taken at the identical pre-test location.
Compliance readings will be made as follows. Depth of penetration of the 1 centimeter squared tip will be recorded at the 3 kilogram force. These data will be assembled into the flexibility coefficient as outlined above. Statistical comparisons of the pre- and post test means will be performed to detect significant changes in the tissue compliance.
Questions that will be answered are as follows: Can the ROM Device significantly increase tissue compliance immediately? Can traditional stretching techniques significantly increase tissue compliance immediately? Is the ROM Device significantly better at increasing tissue compliance in the short term?
This portion of the pilot study is expected to take approximately two months to execute, analyze, and present.
The second part of this pilot study will look at pain threshold. Pain threshold will be conducted on a single quadratus lumborum muscle. Again, each subject will act as his own control. Pre-test pressure threshold readings will be followed by intervention of the ROM Device. The ROM Device will be applied to the tested quadratus lumborum muscle as follows: 20 progressively deeper passes. This will be followed by a 2 minute rest period for each subject. Immediately following this rest period, post-test pressure threshold recordings will be made at the same locations as the pre-test measures were.
Questions that will be answered will be as follows: Can the ROM Device modulate the pressure threshold (pain sensitivity) immediately?
This portion of the pilot study is expected to take approximately two months to execute, analyze and present.
The third part of this study will focus on the attenuation of delayed onset muscle soreness. Subjects will have baseline pressure threshold readings taken on each of their vastus medialis muscles. This will be immediately followed by downhill running to induce muscle soreness and stiffness associated with delayed onset muscle soreness (DOMS).
These subjects will be randomly assigned to one of two groups. One group will apply the ROM Device to their right vastus medialis only, while the other group will apply the ROM Device to their left vastus medialis. The examiner taking the pressure threshold readings will be blinded to this assignment.
The ROM Device will be applied in the following fashion. This is a judicious application of 20 progressively deeper passes, 6 to 8 times per day. ROM intervention will begin immediately where initial readings were made will be the same location each successive pressure threshold readings will be done.
Questions that will be answered will be as follows: Can the ROM Device attenuate the painful effects of DOMS? Does the application of the ROM Device accelerate recovery from DOMS? Is the ROM Device superior to traditional stretching in the attenuation of DOMS?
This part of the pilot study is expected to take 6 weeks to execute, analyze and present.
Estimations of sample size indicate that a minimum of 1296 subjects will be needed. This has been calculated by using a power index of 3.60 and a medium size treatment effect of 0.50. Initial indications are that the ROM Device can have a significant affect on tissue compliance and pressure threshold of muscle. It is for this reason that a medium treatment size effect was chosen for the estimation of the sample size. The alpha level will be set at 0.05 or less. This will reduce the likelihood of committing either an alpha or beta error.
The statistical analysis of the data will be performed by the paired t-test and correlated ANOVA. These test statistics are appropriate for determining the presence of a treatment effect between pre- and post-test means when each subject serves as his own control. This is achieved by pooling the variance and comparing the arithmetic means. For comparison between the treatment effects of the ROM Device and traditional flexibility exercises, the unpaired t-test will be performed. This test statistic is appropriate for determining the effects between similar groups.
Preliminary results have indicated that the ROM Device has a profound effect on muscle flexibility, strength, endurance and recovery from heavy exertion. Since this pilot study is focused on parameters of flexibility (compliance) and muscle sensitivity (pressure threshold), results will be measured in terms of tissue compliance and pressure threshold for pain. It is expected that the study results will support the use of the ROM Device as an important adjunct to flexibility training, exercise recovery, and injury prevention and management in the military.
It has been suggested that the ROM Device can magnify a soldier’s performance by modulating his flexibility. The benefits can have far reaching effects in terms of heightened performance on the battlefield, survivability, injury prevention, accelerated recovery from heavy exercise, modulation of muscle pain, and cost containment.
Once use of the ROM Device has been validated for its intended purposes, additional work should be directed towards issues pertaining to its application and general use. Protocols should be developed for its use in settings where flexibility is the prime directive. The same should be established for settings in which the ROM Device would be used for the management of muscle pain.
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