Pelvic and Lower Limb Kinematics in Individuals With Chronic Low Back Pain During Sit-to-Stand Function: A Cross-Sectional Study.

OBJECTIVES: The aim of this study was to investigate the 3-dimensional movement kinematics of pelvic and lower limb joints in CLBP subjects, compared to healthy individuals, utilizing a functional data analysis (FDA) approach. METHODS: In this study, a 7-camera Qualisys motion capture system was employed to record the kinematics of the pelvic, hip, knee, and ankle joints in 20 patients with low back pain (LBP) and 20 control subjects on both sides during the sit-to-stand motion. An FDA statistical approach was utilized to compare the data collected over time between the 2 groups. The STS task was divided into two distinct phases: the prelift off phase (pre-Lo) and the postlift off phase (post-Lo). RESULTS: During the "pre-Lo phase" of the STS motion, our statistical analysis revealed that the only significant difference between the two groups was a decreased medial rotation (P = .00) in the hip joint position of LBP patients on their dominant side, in comparison to healthy subjects. As for the "post-Lo phase," the LBP group exhibited a more anterior pelvic tilt position (P = .00) and increased pelvic counterclockwise rotation (P = .03) in the sagittal and transverse planes when compared to the control group. Regarding hip joints, the LBP group demonstrated a more flexed position (indicative of reduced extension) on both the dominant (P = .00) and nondominant (P = .00) sides, coupled with diminished abduction (P = .04) and internal rotation (P = .03) of the hip on the dominant side. In relation to the knee and ankle joints, the results indicated a more adducted knee position (P = .00) and decreased ankle joint flexion (P = .02) on the dominant side in CLBP subjects when compared to the healthy group during the STS motion. CONCLUSION: Our findings indicate that patients with CLBP exhibited distinct kinematic patterns in the pelvic and lower limb joints during the STS motion. These kinematic alterations primarily manifest in the joints of the dominant limb, with most of the differences observed during the second phase (postlift off phase) of the motion. It appears that these changes in pelvic and lower limb joint kinematics should be taken into account when planning future rehabilitation programs for CLBP patients engaged in this task.

The impact of myofascial release and stretching techniques on the clinical outcomes of migraine headache: A randomized controlled trial.

BACKGROUND: Migraine patients often have painful trigger points, especially in the area of head and neck. Thus, we aimed to investigate the effect of myofascial release and stretching techniques in the management of migraine headache. MATERIALS AND METHODS: This was a randomized controlled trial study on 40 migraine patients. The subjects in the experimental group received three sessions with a duration of 20 min per session techniques. Databases were analyzed using 2 × 3 repeated-measures analyses of variance (P < 0.05). RESULTS: Experimental group showed a significant reduction in pain intensity (P < 0.001) and the neck disability index score (P < 0.001) and an increase in cervical range of motion (P < 0.001) in all time points after the intervention as compared with baseline and control group (P < 0.001). CONCLUSION: Myofascial release and stretching techniques were effective in improving symptoms in patients with migraine headache.

Multi-session anodal transcranial direct current stimulation enhances lower extremity functional performance in healthy older adults.

The aim of this study was to examine the effects of 5 days of anodal-transcranial direct current stimulation (a-tDCS) over the primary motor cortex (M1) on lower extremity functional performance in healthy elderly people. This was a randomized, double-blinded, sham-controlled study whereby 32 healthy older individuals participated in two groups. The intervention group received 20 min of a-tDCS (1 mA) over the M1 on five consecutive days. The sham group received the same stimulation, but the tDCS device was turned off after 30 s of stimulation. Participants were asked to perform the Timed Up and Go (TUG), 30-s Chair Stand Test (30-s CST), and a Modified Figure of Eight Walk Test (MFEWT) on the first day before tDCS application, immediately, 30 min, and 1 week after the last session of stimulation. Results of the a-tDCS group showed that most of the test values had significant changes in post-test assessments compared to the pre-test (p < 0.05). When comparing the anodal and sham tDCS groups, the results showed a significant improvement in TUG and time-MFEWT immediately after (p = 0.02, p = 0.01), 30 min after (p = 0.04, p = 0.01) and 1 week after the last session of stimulation (p = 0.01, p = 0.01). Improvements in performance of the 30-s CST and the number of steps-MFEWT were not significant, except at 1 week after the last session for the steps-MFEWT (p = 0.04). The application of 20 min a-tDCS over the M1 for 5 consecutive days improves lower extremity functional performance in the healthy older participants.

Examination of Regional Interdependence Theory in Chronic Neck Pain: Interpretations from Correlation of Strength Measures in Cervical and Pain-Free Regions.

OBJECTIVE: Impairments present in chronic pain conditions have been reported not to be limited to the painful region. Pain-free regions have also been proposed to be adversely affected as a cause or consequence of the painful condition. The aim of this study was to investigate the association between muscle strength in painful and pain-free regions and chronic neck pain. DESIGN: A cross-sectional study. SETTING: Rehabilitation hospital laboratory. SUBJECTS: One hundred twenty-two patients with chronic neck pain (87 female) and 98 asymptomatic volunteers (52 female) were included in the study. METHODS: Maximal isometric strength measures of the neck, scapulothoracic, shoulder, trunk, and hip muscles were assessed using a hand-held dynamometer in all participants. Pain intensity and pain-related disability were also assessed in patients through visual analog scale and Neck Disability Index scores, respectively. RESULTS: Principal component analysis revealed one component for each of the studied regions. Multivariate analysis of variance found neck (d = 0.46), scapulothoracic (d = 0.46), shoulder (d = 0.60), trunk flexor (d = 0.38), extensor (d = 0.36), and hip (d = 0.51) strength components to be lower in the neck pain patients compared with asymptomatic participants (P < 0.01). Logistic and linear regression analyses found the shoulder strength component both to be a significant predictor for neck pain occurrence (ß = 0.53, P < 0.01) and to have a considerable effect on pain intensity score (ß=-0.20, P = 0.02), respectively. CONCLUSIONS: The results found that some pain-free regions in addition to the cervical spine to exhibit lower levels of muscular strength in neck pain patients. These findings support the regional interdependence theory, which proposes that impairments are not limited to the painful area and are possibly mediated by central mechanisms.

Relationship Between Hip Extensor Strength and Back Extensor Length in Patients With Low Back Pain: A Cross-Sectional Study.

OBJECTIVE: The purpose of this study was to examine the relationship between hip extensor strength and back extensor length in patients with low back pain (LBP) and healthy controls. METHODS: In 266 patients with LBP and 215 matched controls, back extensor length and hip extensor strength were measured and compared in the 2 groups using an independent t test. The Pearson correlation coefficient was used to determine correlation between these 2 variables. Multivariate logistic regression was used to test the risk of sustaining LBP with having these muscle insufficiencies. RESULTS: A significant difference in hip extensor strength was found between patients with LBP and controls (P < .001). Back extensor length was different in healthy men compared with the patients with LBP (P < .001) but was not significant between women with and without LBP (P = .34). The results showed a significant relationship between back extensor length and hip extensor strength in men with LBP (r = 0.6, P = .01). Multivariate logistic regression revealed that having a weak hip extensor (P = .001) or shortened back extensor (P = .01) could increase the risk of LBP occurrence. CONCLUSION: The findings support the assumptions of the presence of muscle imbalance of hip extensor weakness and back extensor tightness in male patients with LBP and that each muscle impairment may contribute to LBP.

Kinematic Analysis of Pelvic and Lower Limb Joints during Stand-to-sit Movement in Individuals with Chronic Low Back Pain: A cross-sectional study.

Objectives: It is crucial to investigate the daily functions commonly utilized by individuals with low back pain (LBP) due to their implications for recurrence and chronicity. Stand-to-sit (StTS) task is one of the more repetitive functions in human daily life. This study aims to evaluate pelvic and lower limb joint kinematics during the StTS task in individuals with Non-Specific Chronic Low Back Pain (NSCLBP) compared to a healthy control group. Methods: Pelvic and lower limb joint kinematic data in all three planes were recorded from 20 individuals with LBP and 20 healthy individuals using a Qualisys motion capture system during the StTS task. A Functional Data Analysis statistical approach was employed to compare the kinematic data between the two groups. Results: In the initial phase of the movement, we observed a greater anterior pelvic tilt (P=0.028) and an altered pelvic frontal plane motion pattern (P=0.029) in the LBP compared to the healthy group. The only significant differences between the lower limb joint kinematics of the two groups were a less hip external rotation position (P=0.025) and a more knee adduction pattern (P=0.002) on the right side in the LBP subjects compared to the healthy group. Conclusion: Considering a few differences noted between the two groups across various joints and planes evaluated, it appears that the kinematic pattern of the lower limbs does not significantly differ between the NSCLBP and healthy groups during the StTS task in most comparisons. However, distinct kinematic patterns have been observed in the pelvic region, particularly in the sagittal and frontal planes, between the two groups.

The association between myofascial trigger points and the incidence of chronic functional constipation.

INTRODUCTION: Chronic functional constipation (CFC) is the most prevalent type of constipation. Considering the proven effect of pelvic floor muscles dysfunction in these patients' symptom and the fascial connection between pelvic floor and abdominal and lumbopelvic muscles, this study aimed to examine the possible relationship between this muscles and CFC. METHOD: We conveniently selected 100 patients with CFC and 100 healthy participants based on the Rome IV criteria. Two groups were asked to complete the international physical activity questionnaire and food frequency questionnaire. Then both groups were assessed for the presence of trigger points in more prevalent pain sites for each muscle by pressure algometer with 50% of their caught pressure pain threshold. RESULTS: There were no statistical differences between two groups in the intake of calories, carbohydrates, proteins, sugar, fiber, vegetables, and wheat products. Patients had a higher consumption of fat and dairy products. for the physical activity level, a statistical difference showed that patients were less physically active. The comparison of the presence and the number of trigger points for each muscle in patients and control groups indicated more than 50% impairment, and there was a significant difference between two groups. CONCLUSIONS: This study revealed that the relationship between myofascial trigger points of abdominal and lumbopelvic muscles and constipation. In addition to that, it seems that a sedentary life may influence CFC patients' condition. Moreover, it seems that the results of the dietary condition in patients could be because of conscious consumption of some certain foods.

Strength and Range of Motion in the Contralateral Side to Pain and Pain-Free Regions in Unilateral Chronic Nonspecific Neck Pain Patients.

OBJECTIVE: The aim of the study was to determine whether strength and range of motion deficits are present in patients with unilateral chronic neck pain at contralateral side to pain and at other regions. DESIGN: Forty-nine patients with unilateral chronic neck pain and 98 asymptomatic subjects participated in this case-control study. Range of motion and muscle strength of the cervical, shoulder, trunk, and hip regions were assessed bilaterally using inclinometer and dynamometer, respectively. RESULTS: Chronic neck pain patients demonstrated reduced cervical, shoulder, and trunk range of motion in their ipsilateral side to pain comparing the asymptomatic participants (P < 0.05). The ipsilateral side to pain cervical and shoulder range of motion were also significantly lower than the contralateral side to pain (P < 0.05). Significant differences were also observable in the contralateral side to pain comparing the asymptomatic group (P < 0.05). Cervical, shoulder, and scapulothoracic muscles were found weaker both in the ipsilateral side to pain and contralateral side to pain comparing the asymptomatic group (P < 0.05). Ipsilateral side to pain and contralateral side to pain in hip flexors were also found to be significantly weaker than the asymptomatic group (P < 0.01). CONCLUSIONS: The results revealed range of motion and strength deficits in the pain-free regions of the body in unilateral chronic neck pain patients. Findings support the regional interdependence theory and emphasize the need for managing seemingly intact neighboring and more remote regions in unilateral chronic neck pain patients.

Lower limb kinematics in individuals with chronic low back pain during walking.

Several investigators have suggested the presence of a link between Chronic Low Back Pain (CLBP) and lower limbs kinematics that can contribute to functional limitations and disability. Moreover, CLBP has been connected to postural and structural asymmetry. Understanding the movement pattern of lower extremities and its asymmetry during walking can provide a basis for examination and rehabilitation in people with CLBP. The present study focuses on lower limbs kinematics in individuals with CLBP during walking. Three-dimensional movements of the pelvic, hip, knee and ankle joints were tracked using a seven-camera Qualysis motion capture system. Functional dada analysis (FDA) was applied for the statistical analysis of pelvic and lower limbs motion patterns in 40 participants (20 CLBP and 20 controls). The CLBP group showed significantly different hip motion pattern in the transvers plane, altered knee and ankle motion pattern in the sagittal plane on the dominant side and different hip motion pattern in the transvers and frontal planes on the non-dominant side in comparison with the control group over the stance phase. In terms of symmetry, in the CLBP group, hip and knee moved through a significantly different motion patterns in the transvers plane on the dominant side in comparison with the non-dominant side. In the control group, knee moved through a significantly different motion pattern in the transvers plane on the dominant side in comparison with the non-dominant side. In conclusion, low back pain lead to altered movement patterns of the main joints of lower limbs especially on the dominant side during stance phase. Therefore, care should be taken to examine dominant lower limb movement pattern in CLBP to make a better clinical decision.

Effects of Dry Needling Technique Into Trigger Points of the Sternocleidomastoid Muscle in Migraine Headache: A Randomized Controlled Trial.

OBJECTIVE: The study aimed to investigate the effect of dry needling into trigger points of the sternocleidomastoid muscle in migraine headache patients. DESIGN: Forty subjects with a migraine headache, originating from myofacial trigger points into the sternocleidomastoid muscle (20 subjects in dry needling group and 20 subjects in control group) volunteered to participate in this study. The subjects in the treatment group received three sessions of dry needling in the myofascial trigger point region. Headache frequency, headache intensity, headache duration, drug consumption, muscle thickness, pressure pain threshold, and cervical range of motion were assessed before, immediately after intervention, and at 1-mo follow-up period. In addition, this article was extracted from Iranian Register of Clinical Trials Number IRCT20171219037956N1. RESULTS: The experimental group showed significant reduction in the headache parameters immediately after the intervention and at 1-mo follow-up, as compared with the control group. The pressure pain threshold of sternocleidomastoid muscle, cervical range of motion, and muscle thickness significantly increased in the dry needling group in comparison with the control group (P < 0.001). CONCLUSIONS: The application of dry needling technique caused an improvement in symptoms of migraine patients. Therefore, this technique may be prescribed for treating migraine patients with myofacial trigger points in the sternocleidomastoid muscle.

Adding Temporomandibular joint treatments to routine physiotherapy for patients with non-specific chronic neck pain: A randomized clinical study.

INTRODUCTION: Neck Pain can be related to the disorders of other adjacent areas such as the Temporomandibular Joint (TMJ). This study aimed to investigate whether there is value in adding TMJ treatments to routine physiotherapy in patients with non-specific chronic neck pain compared with a control group. METHODS: A randomized, single-blind, clinical study desined including two groups of patients. Group A (20 people) received routine physiotherapy for neck pain and group B (20 people) received TMJ manual therapy plus exercise therapy in addition to routine physiotherapy for neck pain. The Treatment program included six sessions for two days a week over a period of 21 days. Assessments were performed during the first session, in the last session and one month after treatment as a follow-up. Outcome measures included neck range of motion (ROM), neck disability index (NDI) and visual analogue scale (VAS). Before starting the study, the reliability of methods for measuring neck ROM was evaluated. RESULTS: Participants were 21 women and 19 men. Initially, a pilot study was carried out on the 40 volunteers to assess the reliability of the measurement methods, and the results were acceptable. With both the control group and the intervention group, the indexes showed significant improvement (p < 0.001), although the intervention group showed more improvement (p < 0.001). CONCLUSION: This result means adding treatments of TMJ to routine neck physiotherapy can magnify the effect of the intervention, a significant change still in evidence at follow up. Moreover, given the clinically important differences, our results for VAS and NDI were acceptable.

Dry needling versus trigger point compression of the upper trapezius: a randomized clinical trial with two-week and three-month follow-up.

Objectives: The purpose of this randomized controlled trial was to investigate the long-term clinical effect of dry needling with two-week and three-month follow up, on individuals with myofascial trigger points in the upper trapezius muscle. Methods: A sample of convenience (33 individuals) with a trigger point in the upper trapezius muscle, participated in this study. The individuals were randomly assigned to two groups: trigger point compression (N = 17) or dry needling (N = 16). Pain intensity, neck disability, and disability of the arm, hand, and shoulder (DASH) were assessed before treatment, after treatment sessions, and at two-week and three-month follow ups. Results: The result of repeated measures ANOVA showed significant group-measurement interaction effect for VAS (p = .02). No significant interaction was found for NPQ and DASH (p > .05). The main effect of measurements for VAS, NPQ, and DASH were statistically significant (p < .0001). The results showed a significant change in pain intensity, neck disability, and DASH after treatment sessions, after two weeks and three months when compared with before treatment scores in both groups.  There was no significant difference in the tested variables after two-week or three-month as compared to after treatment sessions between the two groups. However, pain intensity after treatment sessions was significantly different between the two groups (p = .02). Discussion: Dry needling and trigger point compression in individuals with myofascial trigger point in the upper trapezius muscle can lead to three-month improvement in pain intensity and disability.

The Impact of Soft Tissue Techniques in the Management of Migraine Headache: A Randomized Controlled Trial.

OBJECTIVE: Individuals with migraine often present with postural faults and muscle tension that are associated with myofascial trigger points (MTrPs). These trigger points may be a contributory factor to the development of migraine headaches. There are many treatments aimed at eliminating MTrPs, such as soft tissue techniques, laser therapy, and needling therapies. Thus, we performed a randomized controlled trial study to investigate the efficacy of soft tissue techniques in the management of migraine headache. METHODS: This study was conducted among individuals with migraine headache in Shiraz in 2018. Forty participants were randomly divided into 2 groups: the soft tissue techniques (treatment) group and the placebo control group. Participants in the treatment group were treated over 6 sessions in 2 weeks (combined MTrP therapy and stretching). Headache parameters, drug consumption, score on the Headache Disability Index, and pressure pain threshold (PPT) were measured before and after the intervention and after a 1-month follow-up period. Data were analyzed with 2 × 3 repeated-measures analyses of variance to investigate the differences in variables between the 2 groups. RESULTS: Compared with baseline and the control group, the treatment group showed a significant reduction in headache parameters (P < .001), drug consumption (P < .001), and Headache Disability Index score (P < .001) immediately after the intervention and after a 1-month follow-up period (all Ps < .001). PPT levels increased in the treatment group in comparison with the control group (P < .001). CONCLUSION: The soft tissue techniques were helpful for improving certain aspects of migraine, such as headache parameters, drug consumption, functional disability, and PPT levels of cervical muscles.

Therapeutic effects of dry needling in patients with upper trapezius myofascial trigger points.

BACKGROUND: Active myofascial trigger points (MTrPs) are major pain generators in myofascial pain syndrome. Dry needling (DN) is an effective method for the treatment of MTrPs. OBJECTIVE: To assess the immediate neurophysiological and clinical effects of DN in patients with upper trapezius MTrPs. METHODS: This was a prospective, clinical trial study of 20 patients with upper trapezius MTrPs and 20 healthy volunteers (matched for height, weight, body mass index and age), all of whom received one session of DN. Primary outcome measures were neuromuscular junction response (NMJR) and sympathetic skin response (SSR). Secondary outcomes were pain intensity (PI) and pressure pain threshold (PPT). Data were collected at baseline and immediately post-intervention. RESULTS: At baseline, SSR amplitude was higher in patients versus healthy volunteers (p<0.003). With respect to NMJR, a clinically abnormal increment and normal reduction was observed in patients and healthy volunteers, respectively. Moreover, PPT of patients was less than healthy volunteers (p<0.0001). After DN, SSR amplitude decreased significantly in patients (p<0.01), but did not change in healthy volunteers. A clinically important reduction in the NMJR of patients and increment in healthy volunteers was demonstrated after DN. PPT increased after DN in patients, but decreased in healthy volunteers (p<0.0001). PI improved after DN in patients (p<0.001). CONCLUSIONS: The results of this study showed that one session of DN targeting active MTrPs appears to reduce hyperactivity of the sympathetic nervous system and irritability of the motor endplate. DN seems effective at improving symptoms and deactivating active MTrPs, although further research is needed. TRIAL REGISTRATION NUMBER: IRCT20130316128.

Neurophysiological and clinical effects of dry needling in patients with upper trapezius myofascial trigger points.

INTRODUCTION: Dry needling (DN) is a widely used in treatment of myofascial trigger points (MTrPs). The purpose of this pretest-posttest clinical trial was to investigate the neurophysiological and clinical effects of DN in patients with MTrPs. METHODS: A sample of 20 patients (3 man, 17 women; mean age 31.7 ± 10.8) with upper trapezius MTrPs received one session of deep DN. The outcomes of neuromuscular junction response (NMJR), sympathetic skin response (SSR), pain intensity (PI) and pressure pain threshold (PPT) were measured at baseline and immediately after DN. RESULTS: There were significant improvements in SSR latency and amplitude, pain, and PPT after DN. The NMJR decreased and returned to normal after DN. CONCLUSIONS: A single session of DN to the active upper trapezius MTrP was effective in improving pain, PPT, NMJR, and SSR in patients with myofascial trigger points. Further studies are needed.

Clinical Effectiveness of Dry Needling Immediately After Application on Myofascial Trigger Point in Upper Trapezius Muscle.

OBJECTIVE: The purpose of this study was to investigate the effect of dry needling (DN) on pain intensity and pressure pain threshold (PPT) compared with ischemic compression (IC) immediately and 48 hours after each treatment session in individuals with myofascial trigger points in the upper trapezius muscle. METHODS: Thirty-one patients with myofascial trigger points in the upper trapezius muscle participated in this study. Patients were randomly assigned to a standard (N = 17) or experimental group (N = 14). The treatment protocol for the standard group consisted of IC, whereas the patients in the experimental group received DN. RESULTS: The results indicated that the effect size of the DN methods for pain intensity and PPT was considerably greater after 2 days compared with immediately after the treatment session. In contrast, the effect of the IC for PPT was greater immediately after treatment compared with the measures after 2 days. There was also no noticeable difference in the effect size for IC on pain intensity between the scores obtained immediately and 2 days after treatment. However, our data also revealed a greater effect size for DN on PPT after 2 days compared with the IC technique. CONCLUSIONS: In this study, DN improved the pain intensity and PPT after 2 days. However, it had no clinical improvement immediately after application because of muscle soreness. Thus, assessment of the effect of DN immediately after application can be criticized, and the results should be interpreted with caution.

The Effects of Oscillatory Biofield Therapy on Pain and Functional Limitations Associated with Carpal Tunnel Syndrome: Randomized, Placebo-Controlled, Double-Blind Study.

OBJECTIVES: Biofield treatments have been used for pain control in patients with cancer and chronic pain. However, research on the effect of biofield treatment on specific somatic disorders is lacking. This study intends to investigate the effect of oscillating biofield therapy (OBFT) on symptoms of carpal tunnel syndrome. DESIGN: Randomized, placebo-controlled, double-blind study. PARTICIPANTS: Thirty patients with chronic carpal tunnel syndrome participated in the study. INTERVENTION: Patients were randomly assigned to active or placebo treatment groups. Those in the treatment group received six sessions of OBFT with intention to treat during a period of 2 weeks. Patients in the placebo group had the same number of treatment sessions with mock OBFT treatment. OUTCOME MEASURE: The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire; Symptom Severity Scale (SSS); and Functional Status Scale (FSS) were used for outcome assessment. RESULTS: Both clinically and statistically significant changes in intensity of pain with activity (95% confidence interval [CI], 2.5-4.2; p = 0.000), night pain (p = 0.000, 95% CI, 3.2-5.7), DASH questionnaire (95% CI, 12.0-21.9; p = 0.000), SSS (95% CI, 0.64-1.15; p = 0.003), and FSS (95% CI, 0.41-0.97; p = 0.029) were found between the treatment and placebo groups. Statistically significant reduction in number of patients with positive results on the Phalen test (87%; p = 0.000), Tinel sign (73%; p = 0.000), and hand paresthesia (80%; p = 0.000) was noted in the treatment group. During 6-month follow-up, 86% of patients in the treatment group remained pain free and had no functional limitations. CONCLUSION: OBFT can be a viable and effective treatment for improving symptoms and functional limitations associated with chronic carpal tunnel syndrome.

Relationship between muscle length and moment arm on EMG activity of human triceps surae muscle.

PURPOSE: The purpose of this experiment was to evaluate the effects of both muscle length and moment arm (MA) on the electromyographic (EMG) and force output of the triceps surae (TS) muscle. RELEVANCE: It is well recognized that changes in muscle length affect both the muscle's force generating capacity as well as its twitch speed. This relationship is well established in animal preparations. Contrary to animal experiments where length can be directly manipulated in isolated muscles, human experiments require that all muscle length changes be secondary to changes in a joint angle. Such experimental manipulations therefore produce changes in not only muscle length, but also in the muscle's MA. The relative effect of muscle length and MA changes on muscle EMG has not been determined in previous experiments. METHODS: This study was executed in two phases. First, using fresh human cadaver lower limbs, data were gathered describing the relationship between knee and ankle angle changes for maintenance of a constant TS muscle length, while its MA at the ankle joint has been changed. In the second phase of the study, results obtained from phase one were applied to 10 healthy adult human subjects to measure the EMG (surface and fine wire) activity of TS at three different conditions: when both length and MA were shortened, when muscle length was decreased given a constant MA and when MA was shortened given a constant muscle length. RESULTS: A significant increase in muscle activity was found as both the length and MA of TS muscle were shortened. A similar pattern of increased muscle activity was observed when the MA was shortened given a constant muscle length. No significant change in TS activity was found when muscle length was shortened, given a constant MA at the ankle joint. CONCLUSIONS: The findings of this study indicate that changes in the Achilles tendon MA predominate over the muscle length variations in determining the level of TS activity when generating plantar flexion torque.

Relationship between mechanical factors and incidence of low back pain.

STUDY DESIGN: A multifactorial cross-sectional nonexperimental design. OBJECTIVES: To collectively investigate the association among 17 mechanical factors and occurrence of low back pain (LBP). BACKGROUND: Several physical characteristics, based on assumptions, clinical findings, and scientific experiments, have been associated with the development of LBP Controversy exists regarding the degree of association between some of these physical characteristics and LBP. Information regarding the degree of association of each factor to LBP is needed for effective prevention and appropriate treatment strategies. METHODS AND MEASURES: A total of 600 subjects participated in this study. Subjects were categorized into 4 groups: asymptomatic men (n = 150, age [mean +/- SD] = 43 +/- 15 years), asymptomatic women (n = 150, age [mean +/- SD] = 43 +/- 13 years), men with LBP (n = 150, age [mean +/- SD] = 43 +/- 14 years), and women with LBP (n = 150, age [mean +/- SD] = 43 +/- 13 years). Seventeen physical characteristics were measured in each group and the relative association of each characteristic with LBP was assessed. RESULTS: Among all the factors tested, endurance of the back extensor muscles had the highest association with LBP Other factors such as the length of the back extensor muscles, and the strength of the hip flexor, hip adductor, and abdominal muscles also had a significant association with LBP. CONCLUSION: It appears that muscle endurance and weakness are associated with LBP and that structural factors such as the size of the lumbar lordosis, pelvic tilt, leg length discrepancy, and the length of abdominal, hamstring, and iliopsoas muscles are not associated with the occurrence of LBP.

Hamstring muscle length and lumbar lordosis in subjects with different lifestyle and work setting: comparison between individuals with and without chronic low back pain.

BACKGROUND AND OBJECTIVES: Shortened hamstring muscle length has been noted in persons with low back pain (LBP). Prolonged sitting postures, such as those adopted during different work settings and sedentary lifestyle has been associated with hamstring shortness and LBP. The purpose of this study was to investigate the effect of lifestyle and work setting on hamstring length and lumbar lordosis in subjects with and without LBP and to identify the relationship between hamstring muscles length and lumbar lordosis in individuals with different lifestyle and work setting. MATERIAL AND METHOD: A total of 508 subjects between the ages of 20 and 65 were selected. Subjects were categorized into two groups of individuals with and without LBP. A questionnaire was used to obtain information about the subjects' lifestyle and work setting. Hamstring muscle length and lumbar lordosis were measured in all subjects. RESULTS: The results showed no significant difference in the number of subjects with different work setting or lifestyle in individuals with and without LBP. Hamstring muscle length or lumbar lordosis was not affected by type of work setting and lifestyle. Our data showed significant difference in hamstring length and no significant difference in lumbar lordosis between subjects with and without LBP in all categories. Lumbar lordosis was not different between individuals with and without hamstring tightness in normal and LBP subjects with different work setting and lifestyle. CONCLUSION: The findings of this study did not support the assumption that work setting and sedentary lifestyle would lead to hamstring tightness in subjects with LBP. It seems that work setting and lifestyle was not a contributing factor for hamstring tightness in subjects with LBP.