The Somatic Connection  |   April 2011
The Somatic Connection
Article Information
The Somatic Connection   |   April 2011
The Somatic Connection
The Journal of the American Osteopathic Association, April 2011, Vol. 111, 197-202. doi:
The Journal of the American Osteopathic Association, April 2011, Vol. 111, 197-202. doi:
“The Somatic Connection” highlights and summarizes important contributions to the growing body of literature on the musculoskeletal system's role in health and disease. This section of JAOA—The Journal of the American Osteopathic Association strives to chronicle the significant increase in published research on manipulative methods and treatments in the United States and the renewed interest in manual medicine internationally, especially in Europe. 
To submit scientific reports for possible inclusion in “The Somatic Connection,” readers are encouraged to contact JAOA Editorial Advisory Board Member Michael A. Seffinger, DO (, or Editorial Board Member Hollis H. King, DO, PhD ( 
Thoracic Spine HVLA Improves Neck Range of Motion and Reduces Neck Pain Up to 6 Months
Lau HM, Wing Chiu TT, Lam TH. The effectiveness of thoracic manipulation on patients with chronic mechanical neck pain—a randomized controlled trial. Man Ther. 2011;16(2):141-147. 
Researchers in Hong Kong conducted a randomized controlled clinical trial to assess the effectiveness of thoracic manipulation (TM) on patients with chronic neck pain. This well-designed study relied on previous research to determine a sample size that would ensure a well-powered study. A total of 120 patients who had been diagnosed by primary care physicians in the outpatient clinic of the Prince of Wales Hospital in Hong Kong were recruited. These patients, between the ages of 18 and 55 years, were randomly assigned to an intervention group or a control group. 
Both groups received infrared radiation (IRR) therapy over the area of neck pain as well as educational materials that included instruction on neck exercises, such as stretching and isometric neck contractions. The authors describe IRR as providing only superficial heating without long-lasting effects. Patients in the intervention group also received high-velocity, low-amplitude (HVLA) thrust manipulation to the thoracic spine. The thrust was delivered at levels determined in a clinical examination of each patient by an experienced physiotherapist, who also administered the TM. 
The study's subjective outcomes measures included the verbal Numeric Pain Rating Scale for neck pain intensity; the Northwick Park Neck Disability Questionnaire (NPQ); and the SF36 Questionnaire, a health-related quality-of-life survey. Objective outcomes measures included cervical range of motion as measured by the Hanoun Multi-Cervical Rehabilitation Unit and a novel measure of the craniovertebral (CV) angle using the Electronic Head Posture Instrument (EHPI). 
All participants completed the outcomes measures and were assessed by a blinded assessor 4 times: at baseline, immediately after 8 sessions of treatment (at a rate of 2 sessions per week), at 3-month follow-up, and at 6-month follow-up. 
Between-group comparisons by analysis of variance (ANOVA) showed that, at immediate postintervention, patients who received TM had statistically significant greater reduction in subjective pain intensity, improved CV angle, improved NPQ score, improved neck flexion (ie, forward bending), and an improved Physical Component Score on the SF36 Questionnaire, compared with patients in the control group. All of these improvements remained statistically significant at 6-month follow-up. 
This study is unique in 2 important ways. It is the largest and best-powered study assessing the impact of HVLA TM on a patient group with an established diagnosis of chronic neck pain. In addition, measuring the CV angle with the EHPI is a relatively new and potentially useful outcomes measure in manual medicine and osteopathic manipulative medicine research. 
From the osteopathic perspective, it is not surprising that a thoracic spine HVLA intervention would improve cervical alignment, reduce cervical pain, and improve cervical range of motion. An interesting point of discussion is whether the intervention in this study would have produced similarly beneficial results had it been delivered by an osteopathic physician. From the description in the article, the TM maneuvers used by Lau et al are virtually identical to those taught and practiced in the osteopathic medical profession. 
As this study suggests, other professions that use manually guided forces in the delivery of healthcare are conducting research that must be considered by osteopathic researchers and practitioners. Would comparable treatment by an experienced osteopathic physician produce even greater benefit than that demonstrated by Lau et al? This question is worthy of research within the osteopathic medical profession.—H.H.K. 
Audible Pop From Thoracic Spinal Thrust Not Related to Neck Pain Relief or Pupillary Autonomic Changes
Sillevis R, Cleland J. Immediate effects of the audible pop from a thoracic spine thrust manipulation on the autonomic nervous system and pain: a secondary analysis of a randomized clinical trial. J Manipulative Physiol Ther. 2011;34(1):37-45. 
Osteopathic physicians use thoracic spinal manipulation, including thrust techniques that generate an audible popping sound, to treat patients with somatic dysfunction. As abstracted by Hollis H. King, DO, PhD, in the present collection of articles in “The Somatic Connection,” researchers have demonstrated relief of cervical pain using a thoracic thrust manipulative procedure (Lau et al. Man Ther. 2011;16[2]:141-147). In the April 2010 issue of JAOA—The Journal of the American Osteopathic Association, osteopathic physicians and other researchers at Nova Southeastern University in Fort Lauderdale, Florida, reported the effects of osteopathic manipulative treatment on pupil diameter as a measure of autonomic function (Sandhouse et al. 2010;110[4]:239-243). 
In a randomized controlled clinical trial, Sillevis and Cleland recruited patients with chronic neck pain to investigate the immediate effects of audible thoracic spinal joint sounds on verbalized subjective pain levels and on objective measures of autonomic nervous system activity following supine T3-T4 spinal thrust manipulation. The autonomic nervous system measures were made with a fully automated pupillometry system consisting of goggles and an infrared camera (Vorteq; Micromedical Technologies Inc, Chicago, Illinois). The researchers reasoned that with reduction of pain, a measurable decrease in sympathetic tone would be detected in pupil diameter. Chronic neck pain was operationally defined as persistent, nonspecific, and nonfluctuating in intensity for at least 3 months in the cervical and upper thoracic spine to the level of T4. This pain was further defined as being provoked with neck movements. The thoracic thrust or mobilization was performed by a physical therapist who had more than 15 years of clinical experience in manual therapy. 
The 100 participants in the study were selected by convenience sample as consecutive patients presenting with chronic cervical pain between May 2008 and August 2008 at any of 5 outpatient physical therapy clinics in northwestern Indiana. Participants were randomized into either a “manipulation” group (n=50; 40 women, 10 men; mean age, 42.70 years; mean visual analog scale [VAS] pain score, 38/100 mm; mean duration of symptoms, 23.3 months) or a “mobilization” group (n=50; 37 women, 13 men; mean age, 46.84 years; mean VAS pain score, 33/100 mm; mean duration of symptoms, 25.3 months). The VAS scores and the pupil responses were measured in a controlled manner before, during, and for 60 seconds after the manual interventions. Manipulation consisted of transthoracic thrust in the supine position with stabilization of 1 side of T4 using an open-palm hand. Mobilization used similar contact as manipulation but with 3 seconds of pressure and no thrust. This mobilization technique was described as a “placebo” intervention in the article. 
Results of the study showed no statistically significant difference between the 2 groups at any stage of the study in terms of pain relief or pupillary response. Subgroup analyses of thrust with audible pop (n=32) vs thrust with no audible pop (n=18) vs mobilization (n=50) showed no statistically significant difference in the amount of change in pupil diameter among these 3 groups (P=.31, P=.44, and P=.47, respectively). Although statistically significant reductions in pain were found in the no-pop thrust group (P=.031) and the multiple-pop thrust group (P=.014), the reductions in neither group reached the minimal clinically significant level of 13 mm on the 100-mm VAS. 
Sillevis and Cleland concluded that the presence of joint sounds resulting from a transthoracic T3-T4 thrust manipulation does not influence the overall activity of the autonomic nervous system or contribute to the reduction of pain in patients with chronic neck pain. As a result of methodologic differences between this study and the previously mentioned study by Lau et al, it is impossible to compare results between these 2 studies. 
Results of the research by Sillevis and Cleland should be interpreted with caution because of various limitations with the study. On face value, it would seem that the study provides evidence that thoracic spine thrust manipulation is not indicated for reducing symptoms in patients with chronic neck or upper back pain. However, it must be noted that no diagnosis of somatic dysfunction was reported by Sillevis and Cleland. In addition, no attempt was made to identify the cause of, or the spinal segments involved in, the production of the patients' pain complaints. 
The mean duration of symptoms of participants in this study was more than 2 years. It is likely that these patients had central and peripheral sensitization and cervical and thoracic somatic dysfunction, as well as somatic dysfunction in other areas of the body that could have contributed to their overall pain sensation. The investigators made no attempt to identify or address dysfunctional spinal joints or other problems in any body region that may have been related to the pain. 
Thoracic high-velocity, low-amplitude techniques of osteopathic manipulative treatment are indicated for patients in whom somatic dysfunction has been diagnosed in vertebral segments. Hopefully, researchers in osteopathic medicine can improve upon the study design by Sillevis and Cleland to make the results of their study more clinically applicable and to improve its external validity.—M.A.S. 
Lymphatic Pump With Activation May Worsen Air Trapping in Patients With COPD
Noll DR, Johnson JC, Baer RW, Snider EJ. The immediate effect of individual manipulation techniques on pulmonary function measures in persons with chronic obstructive pulmonary disease. Osteopath Med Prim Care. 2009;3:9. 
In a study published in 2008, researchers at the A.T. Still University of Health Sciences-Kirksville College of Osteopathic Medicine in Missouri reported that the multitechnique osteopathic manipulative treatment (OMT) protocol they used to treat patients with chronic obstructive pulmonary disease (COPD) resulted in worsening of air trapping during the 30 minutes immediately after the OMT session, relative to a sham control group (Noll DR et al. J Am Osteopath Assoc. 2008;108[5]:251-259). As a follow-up to that study, Noll et al reported results of a subsequent study, published in 2009, designed to delineate which of a series of OMT procedures used for patients with COPD are responsible for the air trapping observed in the first study. 
Two osteopathic physicians (ie, DOs) provided OMT in the first study. These DOs used 7 standardized OMT techniques, including the thoracic lymphatic pump (TLP) technique with slight modifications. In administering TLP to the study participants, 1 of the DOs pressed the thoracic cage as the patient exhaled throughout the exhalation phase, and the other DO had the patient inhale against the DO's counterforce resistance, which he released suddenly, allowing a gasp of inhaled air to rush into the lungs. The latter procedure, called TLP with activation, was hypothesized to be the cause of the increased air trapping. To test this hypothesis, 4 OMT procedures used in the first study were evaluated singly in the second study for their effects on pulmonary function: TLP with activation, TLP without activation, rib raising, and myofascial release. 
After sample size power analysis, the researchers recruited 25 participants with COPD and a forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ratio of 70% or less of the predicted value. The participants consisted of 11 women and 14 men with a mean (SD) age of 68 (8) years and an age range of 51 to 80 years. Most of the participants had received OMT or chiropractic care, but not within the 3 months previous to this study. Participants received 4 single-technique treatment sessions, evaluating the 4 OMT procedures in random order, with a 4-week washout period between sessions. A minimal-touch control was provided at a separate session, also in random order. Pulmonary function measures were obtained at baseline and at 30-minutes posttreatment. A follow-up phone call the day after treatment surveyed the patients for adverse effects. 
Results showed that all 4 of the tested OMT procedures were associated with adverse posttreatment changes in pulmonary function measures. However, different techniques caused changes in different measures. As hypothesized, TLP with activation increased posttreatment residual volume (RV) of the lungs compared to baseline (P=.03). Neither TLP without activation, rib raising, or myofascial release increased posttreatment RV compared to baseline (P=.48, P=.62, and P=.34, respectively). Adverse effects of all treatments were transitory and mild, consisting mostly of posttreatment soreness to the chest wall. 
Despite the lack of demonstrated improvement in pulmonary function measures, the majority of participants—including 74% of patients who had received TLP with activation—reported that they believed they could breathe better after receiving OMT. None of the participants experienced a COPD exacerbation episode after any of the treatment sessions. 
The 2009 study by Noll et al was the first randomized controlled clinical trial to compare the effectiveness of one OMT technique against another using pulmonary function tests in patients with COPD. However, this is not a definitive study, because it is unknown if the OMT procedures produced any long-term (ie, 30 minutes-1 month) effects on pulmonary function. It is not unusual for a treatment to initially exacerbate a condition before showing a delayed onset of efficacy. For example, even cough medicines often induce a cough when first taken, and bronchodilators are known to elicit initial bronchoconstriction. 
Noll et al recommended exercising caution in the use of the tested OMT procedures, especially TLP with activation, in patients with acute exacerbations of COPD. Although the sample size of stable patients with COPD was small, the researchers boldly extrapolated the results of their data, stating the following: the context of an acute exacerbation of COPD, where even small transient adverse changes may have serious consequences, these techniques should be considered contraindicated. Further, the TLP with activation and myofascial release techniques may be relatively contraindicated even in persons with stable COPD since these techniques may increase RV.

Seemingly contrary to this caution, Noll et al also stated that all OMT procedures tested in their study appeared to be safe for use in clinical practice: 

Despite the adverse changes in pulmonary function measures, the four osteopathic techniques appear to be reasonably safe for persons with stable COPD. The four techniques were shown to be `safe' in the sense that none of the study participants reported an acute exacerbation of symptoms which required a change in medical treatment or resulted in hospitalization. Also, the majority of subjects reported feeling and breathing better after treatment.

These statements raise questions regarding who is to decide whether a particular OMT procedure is contraindicated in a patient population. Should clinical researchers who attempt to apply results of a small sample to a larger population make such decisions? Should osteopathic manipulative medicine (OMM) educators at the graduate or postgraduate level make the decisions? Should OMM specialists in the field decide? Or should these decisions be left to lawyers and politicians after they review the adverse events in clinical studies? 
Certainly, these questions need to be addressed by osteopathic physicians who use OMM regularly in clinical practice and who teach OMM to students at our colleges of osteopathic medicine.—M.A.S. 
Osteopathic Manipulative Therapy Aids Pain Control in Patients With Spinal Cord Injury
Arienti C, Daccò S, Piccolo I, Redaelli T. Osteopathic manipulative treatment is effective on pain control associated to spinal cord injury [published online ahead of print December 7, 2010]. Spinal Cord. doi:10.1038/sc.2010.170. 
Osteopathic researchers at the Istituto Superiore di Osteopatia and anesthetists and physiatrists at the Spinal Unit of Niguarda Ca' Granda Hospital, both in Milan, Italy, reported on the effects of osteopathic manipulative therapy for chronic pain management in patients with spinal cord injury. Participants in this landmark clinical trial were 47 adult patients who had been stable for at least 6 months after sustaining traumatic spinal cord lesions. Thirty-three of the patients had complete spinal cord transection and 14 had incomplete transection. Inclusion in the study required chronic pain scores between 6 and 10 on the verbal numeric scale (VNS). 
Two cohorts were recruited. Cohort A, consisting of 26 patients recruited by a team of physiatrists and anesthetists, was characterized by having primarily neuropathic-type (n=16) or nociceptive-type (n=10) pain syndrome. This cohort included 22 men and 4 women with a mean (standard deviation [SD]) age of 36 (9.95) years. Twenty-one patients in cohort A had a complete spinal cord transection and 5 had an incomplete spinal cord transection. Cohort B, consisting of 21 patients recruited by anesthetists, was characterized by purely neuropathic-type pain. This cohort included 17 men and 4 women with a mean (SD) age of 41 (13.36) years. Twelve patients in cohort B had a complete spinal cord transection and 9 had an incomplete spinal cord transection. 
Participants were randomized to 1 of 3 treatment groups: a pharmacologic (Ph) group, a pharmacologic plus osteopathic manipulative therapy (PhO) group, and an osteopathic manipulative therapy only (Os) group. All participants were given antidepressant medications. In addition, treatment in the Ph group and PhO group included pregabalin (600 mg daily) for neuropathic pain and acetaminophen (2-4 g daily) for nociceptive-type pain, as determined by the anesthetists. 
Treatment in the Os group consisted of a series of myofascial release, strain-counterstrain, muscle energy, soft tissue, and cranial sacral approaches, as determined by the osteopath based on principles published in an article by Michael L. Kuchera, DO (J Am Osteopath Assoc. 2007;107[suppl 6]:ES28-ES38). Osteopathic manipulative therapy was provided to patients in 7 sessions lasting 45 minutes each—1 session per week during the first month, 1 session every 2 weeks during the second month, and 1 session during the third month. 
To evaluate treatment outcomes, VNS scores from 0 to 10 were determined at follow-up intervals. Cohort A was evaluated at 1, 3, 8, 12, 13, 16, 20, and 24 weeks, and cohort B was evaluated at 1, 3, and 8 weeks. 
In the cohort A phase of the study, researchers found no statistically significant difference in initial mean VNS scores among participants in the 3 allocation groups (P=.62). Pain scores in each group improved over the first 12 weeks regardless of the type of intervention (P<.01), with pain improvement occurring faster in the Ph and PhO groups than in the Os group. 
An interesting aspect of the research design of this study was that the PhO group intervention began only after pain improvement plateaued in the Ph group at 12-week follow-up. The PhO group then showed improvement in pain relief, compared with the Ph and Os groups, at the next 3 follow-up periods—13 weeks, 16 weeks, and 20 weeks (P=.04 vs Ph; P=.03 vs Os). At these follow-up times, VNS values in the Ph and Os groups remained constant, with no statistically significant difference (P=.88). Thus, there was a plateau in the pain relief trend after 12 weeks in the Ph and Os groups. After 20 weeks, no further pain relief was reported in the PhO group (P=.28). 
In the cohort B phase of the study, the 3 groups of patients were homogenous for pain perception at the time of enrollment (P=.75). Pain progressively diminished in each of the 3 groups throughout the 8-week evaluation period regardless of intervention, with the 3 treatments yielding statistically similar rates of improvements at the 1-week, 3-week, and 8-week points (P=.26). However, patients in the PhO group had statistically significant greater pain relief than patients in the other groups at the 8-week point compared to baseline (P=.05 vs Ph; P=.001 vs Os). 
This study was the first randomized controlled cohort study of the use of osteopathic manipulative therapy for relieving chronic pain in patients with disabling spinal cord lesions. The primary outcome measure was pain as verbally expressed by the patient. No somatic findings were reported. Benefits of osteopathic manipulative therapy for pain relief were demonstrated compared with benefits achieved with medications commonly used to treat these patients. The combination of osteopathic manipulative therapy with pharmacotherapeutics improved pain scores more so than either intervention alone.—M.A.S. 
Manipulation and Mobilization of Lumbar Spine Does Not Increase Range of Motion or Reduce Bending Stiffness in Healthy Individuals
Stamos-Papastamos N, Petty NJ, Williams JM. Changes in bending stiffness and lumbar spine range of movement following lumbar mobilization and manipulation. J Manipulative Physiol Ther. 2011;34(1):46-53. 
In previous editions of “The Somatic Connection,” I have brought to the attention of readers novel examples of techniques and instrumentation that may be of use in osteopathic manipulative treatment research, such as muscle functional magnetic resonance imaging (J Am Osteopath Assoc. 2010;110[5]:271-272) and pressure pain threshold instrumentation (J Am Osteopath Assoc. 2009;109[12]:624-625). This study by Stamos-Papastamos et al was also selected because of its potential usefulness to researchers in osteopathic medicine, though results of the interventions used by the authors were statistically insignificant. 
Stamos-Papastamos and colleagues in the United Kingdom used procedures developed in previous studies for measuring spinal bending stiffness and flexion and extension range of motion (ROM) during application of force to the lumbar spine. The objective of the authors was to investigate the immediate effects of lumbar posteroanterior mobilization and lumbar rotational manipulation on spinal bending stiffness and lumbar ROM. The power analysis determined that 32 participants were needed in the study. The participants were asymptomatic students recruited from the School of Health Professions at the University of Brighton in Eastbourne, England. 
The 32 participants (16 men; 16 women; mean [SD] age, 25.5 [4.5] y) in this same-subject, repeated-measures, crossover trial served as their own control group, in that a random coin toss determined if they received the manipulation or mobilization first. Each participant had his or her spinal bending stiffness and lumbar ROM measured, followed by either the manipulation or mobilization intervention and immediate reassessment of the outcome measures. At least 48 hours later, the participants again had the outcome measure assessment, followed by the type of intervention not delivered on the first visit and immediate reassessment of the outcome measures. The subjects had been told to behave as they normally would between the 2 intervention sessions. 
The researchers described the manipulation intervention as a rotational thrust technique on both sides at the L4/L5 segmental level, a technique that appears to approximate the high-velocity, low-amplitude (HVLA) osteopathic maneuver frequently called a lumbar roll. The mobilization intervention was described as 3 sets of 1-minute grade-4 (ie, firm) posteroanterior pressures into perceived resistance at the L4/L5 paraspinal level while the participant was prone. 
The instrumentation used by the researchers was described as follows: 

A custom-made wooden and padded treatment plinth securely screwed on a nonconductive force platform (Advanced Mechanical Technology Inc, Watertown, MA) was used to quantify the magnitude of [posteroanterior] force applied to the spine.... An electromagnetic tracking system (Fastrak; Polhemus Navigation, Colchester, VT), recording at 100 Hz, was used to measure spinal angular displacement during force application for the calculation of bending stiffness and to measure lumbar flexion and extension ROM.

The results of the study revealed no statistically significant differences between the preintervention and postintervention measures of spinal bending stiffness or lumbar flexion and extension ROM. The authors concluded that in the asymptomatic individuals, in whom pain was not a factor, musculoskeletal biomechanics were not changed significantly by the type of manipulation or mobilization interventions that had produced changes in symptomatic individuals in previous studies using similar outcome measures and assessment techniques. Those previous studies had also used pain assessment as an outcome measure. Thus, the reduction of pain in those studies was apparently an important factor in the observed improvement in spinal bending stiffness and lumbar ROM. 
Secondary analysis by Stamos-Papastamos et al revealed that if initial stiffness and ROM levels in an individual were below certain levels, there was a tendency for improvement in the stiffness and ROM that approached statistical significance. 
Despite the statistically insignificant results reported by Stamos-Papastamos et al, osteopathic physicians should consider using the measurements and instrumentation described in this study for patients with lumbar spine dysfunction because of the previous studies that established reliability of these measures. The measurements and instrumentation used in this and similar studies may be of value in evaluating dimensions pertinent to research questions on the impact of osteopathic manipulative treatment.—H.H.K. 
Sacral HVLA May Improve Pelvic Floor Muscle Tonus and Function in Women
de Almeida BS, Sabatino JH, Giraldo PC. Effects of high-velocity, low amplitude spinal manipulation on strength and the basal tonus of female pelvic floor muscles. J Manipulative Physiol Ther. 2010;33(2):109-116. 
Published research reviewed in “The Somatic Connection” in the December 2009 issue of JAOA—The Journal of the American Osteopathic Association (Licciardone JC et al. Am J Obstet Gynecol. 2010;202[1]:43.e1-8) demonstrated the benefit of prenatal osteopathic manipulative treatment (OMT) for improved functional capacity during the third trimester of pregnancy. The Licciardone et al study provided data supportive of the benefit of OMT in the treatment of women with back pain during pregnancy. In addition, clinical experience by osteopathic physicians who use OMT include reports of other benefits to the genitourinary system of women: reduced frequency of urinary tract infections and menstrual cramps and improved outcomes of pregnancy, labor, and delivery. Although research on genitourinary function in women appears to be a fertile field of discovery, relatively little attention is paid to this important area of women's health. 
In an experimental, noncontrolled, nonrandomized study, researchers at the State University of Campinas in Sao Paulo, Brazil, recruited 40 healthy women for an evaluation of intravaginal pressure (IVP) before and after high-velocity, low-amplitude (HVLA) thrust to the sacrum. The objective of this pilot study was to quantify the effects of HVLA on IVP, allowing measurement of the basal tonus of the perineal muscles of the pelvic floor using a perineometer. 
Study participants were recruited consecutively from a healthy population of women on the university's campus. Exclusion criteria eliminated women who had delivered vaginally or who had a history of urinary tract infections. Some participants had delivered via cesarean section. The mean (SD) age of participants was 33.6 (5.37) years. 
The modified Kegel perineometer used in this study has a semirigid rubber tube 10 cm in length and 3.5 cm in diameter that is inserted into the vagina. This instrument makes measurements of pelvic floor muscle tonus through pressure electromyography, the electronic recording of muscular contractions. A catheter from the perineometer connects to a conventional mercury manometer. Calibration of the perineometer was performed for each participant to establish a baseline measure of pelvic floor muscle tonus. 
Participants were instructed to carry out 3 types of muscle contractions. The first contraction was fast, or phasic, contraction of the anus-elevating muscles, which requires use of type II (ie, fast- or phasic-type) muscle fibers. The second contraction was a persistent contraction of the anus-elevating muscles, or tonic-contraction, which was maintained for 10 seconds and was considered an endurance function carried out by type I (ie, slow twitch) muscle fibers. The third contraction was contraction of the anus-elevating muscles simultaneously with the gluteus, abdominus transverses, and adduction muscles. 
Following participant instruction in each of these pelvic floor muscle contractions, the perineometer was inserted into the vagina while the participant was supine. The participant then performed each of the 3 contractions, and electronic measures of perineal muscle pressure were recorded. Next, the participant was placed in a lateral recumbent position, and HVLA manipulation was applied to the sacrum. After the HVLA manipulation, the perineal muscle pressure was again measured and recorded for each type of contraction. 
Results showed a statistically significant increase from baseline pelvic floor tonus to post-HVLA pelvic floor tonus for all 3 types of contractions in terms of IVP (P<.05). 
The authors acknowledged the anatomic complexity of the perineal structures and were unable to delineate a detailed theory of perineal functionality. However, they concluded that evidence supported the strengthening of pelvic floor muscle tonus after sacral HVLA in healthy women. 
In the discussion section of the article, de Almeida et al reported that their findings were consistent with literature showing that spinal manipulation acts on the activity of the α motor neurons, regulating muscular tonus and causing an increase in the muscular contraction force. The authors also noted that the observed increase of basal tone after HVLA treatment is contrary to literature that reports a decrease of muscular hypertonicity after spinal manipulation. However, the authors acknowledged that as this was only a pilot study, carefully controlled studies of this matter were needed. Such studies have potential to be of particular benefit to women with perineal hypotony. 
It should be noted that the lead author of this study—Berta Simon Nogueira de Almeida, PhD, DO—is a Brazilian osteopath who works as a physiotherapist in the gynecology clinic of the State University of Campinas, where the study was carried out. It may be worthwhile to introduce this study's line of research to the osteopathic medical profession in the United States for the heuristic value it represents regarding the osteopathic philosophy of exploring structure-function relationships. The results of this study are consistent with osteopathic medical research related to women's health (Boesler D et al. J Am Osteopath Assoc. 1993;93[2]:203-214; King HH et al. J Am Osteopath Assoc. 2003;103[12]:577-582; Licciardone JC et al. Am J Obstet Gynecol. 2010;202[1]:43.e1-8).—H.H.K.