Does the motor unit synchronization induced by vibration enhance maximal voluntary isometric contraction force? A randomized controlled double-blind trial.

OBJECTIVES: Motor unit synchronization has been proposed as a potential mechanism underlying muscle strength gains for vibration training, but it has yet to be definitely demonstrated. Aim of this study was to determine whether motor unit synchronization induced by vibration has an effect on isometric muscle strength. METHODS: Thirty-six healthy volunteers were randomized into two groups: the vibration and the control (sham vibration) groups. Two sets of test measurements and vibration resistance training between the two sets were applied to the right wrist flexors. The maximal voluntary isometric contraction force, and flexor carpi radialis EMG activity were recorded in the first (without vibratory stimulation) and the second (with vibratory stimulation) set. RESULTS: There was no difference in the normalized peak force between the first and the second set in the vibration group (p=0.554). Motor units fired with maximal voluntary isometric contraction synchronized at the vibration frequency (25 Hz) during vibration in all participants of the vibration group. CONCLUSION: The present study indicates that vibration-induced motor unit synchronization does not have a significant effect on the maximal voluntary isometric contraction force.​.

Prevalence and risk factors for vitamin D deficiency in patients with widespread musculoskeletal pain.

BACKGROUND/AIM: The aim of this study was to examine the prevalence of 25-hydroxyvitamin D (25(OH) vitamin D) deficiency in patients complaining of widespread musculoskeletal pain. MATERIALS AND METHODS: In this cross-sectional study, 14,925 patients (13,589 females and 1336 males; mean age: 47.0 years, range: 20-99 years) were included. Serum 25(OH) vitamin D was measured by ELISA. The patients were classified into two groups: 1) patients with vitamin D deficiency (<20 ng/mL) and 2) patients without vitamin D deficiency (>20 ng/mL). RESULTS: The prevalence of vitamin D deficiency was 73.9%. A multivariate logistic regression model showed that low 25(OH) vitamin D level was associated with sex, age, and month in which 25(OH) hypovitaminosis was determined. The risk of a low 25(OH) vitamin D was level was 1.74 times higher in female patients than in males. The risk of low 25(OH) vitamin D level was highest in March during the year. CONCLUSION: Our results indicate that vitamin D deficiency should be considered in patients with widespread musculoskeletal pain and some precautions, such as sunbathing during summer, should be recommended for patients with a risk of vitamin D deficiency.

Whole-body vibration induces distinct reflex patterns in human soleus muscle.

The neuronal mechanisms underlying whole body vibration (WBV)-induced muscular reflex (WBV-IMR) are not well understood. To define a possible pathway for WBV-IMR, this study investigated the effects of WBV amplitude on WBV-IMR latency by surface electromyography analysis of the soleus muscle in human adult volunteers. The tendon (T) reflex was also induced to evaluate the level of presynaptic Ia inhibition during WBV. WBV-IMR latency was shorter when induced by low- as compared to medium- or high-amplitude WBV (33.9±5.3msvs. 43.8±3.6 and 44.1±4.2ms, respectively). There was no difference in latencies between T-reflex elicited before WBV (33.8±2.4ms) and WBV-IMR induced by low-amplitude WBV. Presynaptic Ia inhibition was absent during low-amplitude WBV but was present during medium- and high-amplitude WBV. Consequently, WBV induces short- or long-latency reflexes depending on the vibration amplitude. During low-amplitude WBV, muscle spindle activation may induce the short- but not the long-latency WBV-IMR. Furthermore, unlike the higher amplitude WBV, low-amplitude WBV does not induce presynaptic inhibition at the Ia synaptic terminals.

Vibration parameters affecting vibration-induced reflex muscle activity.

PURPOSE: To determine vibration parameters affecting the amplitude of the reflex activity of soleus muscle during low-amplitude whole-body vibration (WBV). MATERIALS AND METHODS: This study was conducted on 19 participants. Vibration frequencies of 25, 30, 35, 40, 45, and 50 Hz were used. Surface electromyography, collision force between vibration platform and participant's heel measured using a force sensor, and acceleration measured using an accelerometer fixed to the vibration platform were simultaneously recorded. RESULTS: The collision force was the main independent predictor of electromyographic amplitude. CONCLUSION: The essential parameter of vibration affecting the amplitude of the reflex muscle activity is the collision force.

Tendon reflex is suppressed during whole-body vibration.

In this study we have investigated the effect of whole body vibration (WBV) on the tendon reflex (T-reflex) amplitude. Fifteen young adult healthy volunteer males were included in this study. Records of surface EMG of the right soleus muscle and accelerometer taped onto the right Achilles tendon were obtained while participant stood upright with the knees in extension, on the vibration platform. Tendon reflex was elicited before and during WBV. Subjects completed a set of WBV. Each WBV set consisted of six vibration sessions using different frequencies (25, 30, 35, 40, 45, 50Hz) applied randomly. In each WBV session the Achilles tendon was tapped five times with a custom-made reflex hammer. The mean peak-to-peak (PP) amplitude of T-reflex was 1139.11±498.99µV before vibration. It decreased significantly during WBV (p<0.0001). The maximum PP amplitude of T-reflex was 1333±515µV before vibration. It decreased significantly during WBV (p<0.0001). No significant differences were obtained in the mean acceleration values of Achilles tendon with tapping between before and during vibration sessions. This study showed that T-reflex is suppressed during WBV. T-reflex suppression indicates that the spindle primary afferents must have been pre-synaptically inhibited during WBV similar to the findings in high frequency tendon vibration studies.

The effect of single extremity-vibration on the serum sclerostin level.

[Purpose] Sclerostin is mechanosensitive protein that is produced exclusively by osteocytes. It was reported that the plasma sclerostin level increases in the 10th minute after the application of Whole-Body Vibration. The aim of this study was to determine whether single extremity-vibration induces any change in the serum sclerostin level. [Subjects and Methods] Eight healthy young-adult volunteers were recruited for this pilot study. The participants sat on a chair with their left hip and knee joints flexed at 90 degrees. The lower leg was exposed to vibration: 40 Hz, 4 mm, 60 s. Blood samples were collected before and after the vibration. The serum sclerostin levels were blindly measured in dual-controlled blood samples. [Results] The serum sclerostin level before vibration was 328.2±589.9 pg/ml, and it showed no significant change after vibration. [Conclusion] Unlike Whole-Body Vibration, Single-Extremity Vibration did not affect the serum sclerostin level significantly. This finding can be explained by the limited bone volume exposed to vibration. Bone volume exposed to vibration is less during Single-Extremity Vibration than during Whole-Body Vibration.

Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

[Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50 Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8 ms; 95% confidence interval [CI]: 39.0-41.9 ms) was significantly longer than T-reflex latency (34.6 ± 0.5 ms; 95% CI: 33.6-35.5 ms) and the mean difference was 6.2 ms (95% CI of the difference: 4.7-7.7 ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex.

Serum sclerostin is decreased following vitamin D treatment in young vitamin D-deficient female adults.

Sclerostin is produced almost exclusively by osteocytes, which also express receptors for 1,25 dihydroxyvitamin D3. The aim of this study was to investigate the effects of vitamin D3 treatment on serum sclerostin levels in young adult females with severe vitamin D deficiency. A total of 26 subjects were treated orally with calcium (1.200 mg/day for 2 months) and vitamin D3 (300.000 IU/week for 1 month). Serum 25-hydroxyvitamin D (25(OH)D) and sclerostin levels were measured before and after treatment. Baseline serum 25(OH)D and sclerostin levels were at 5.7 ± 2.4 ng/mL and 39.1 ± 14.4 pg/mL, respectively. Serum 25(OH)D was significantly increased, to 62.4 ± 18.7 ng/mL, following treatment; serum sclerostin was significantly decreased, to 29.3 ± 8.8 pg/mL. We conclude that serum sclerostin level is decreased following vitamin D3 treatment in patients with vitamin D deficiency.

A Randomized Trial on the Effect of Bone Tissue on Vibration-induced Muscle Strength Gain and Vibration-induced Reflex Muscle Activity.

BACKGROUND: Whole-body vibration (WBV) induces reflex muscle activity and leads to increased muscle strength. However, little is known about the physiological mechanisms underlying the effects of whole-body vibration on muscular performance. Tonic vibration reflex is the most commonly cited mechanism to explain the effects of whole-body vibration on muscular performance, although there is no conclusive evidence that tonic vibration reflex occurs. The bone myoregulation reflex is another neurological mechanism used to explain the effects of vibration on muscular performance. Bone myoregulation reflex is defined as a reflex mechanism in which osteocytes exposed to cyclic mechanical loading induce muscle activity. AIMS: The aim of this study was to assess whether bone tissue affected vibration-induced reflex muscle activity and vibration-induced muscle strength gain. STUDY DESIGN: A prospective, randomised, controlled, double-blind, parallel-group clinical trial. METHODS: Thirty-four participants were randomised into two groups. High-magnitude whole-body vibration was applied in the exercise group, whereas low-magnitude whole-body vibration exercises were applied in the control group throughout 20 sessions. Hip bone mineral density, isokinetic muscle strength, and plasma sclerostin levels were measured. The surface electromyography data were processed to obtain the Root Mean Squares, which were normalised by maximal voluntarily contraction. RESULTS: In the exercise group, muscle strength increased in the right and left knee flexors (23.9%, p=0.004 and 27.5%, p<0.0001, respectively). However, no significant change was observed in the knee extensor muscle strength. There was no significant change in the knee muscle strength in the control group. The vibration-induced corrected Root Mean Squares of the semitendinosus muscle was decreased by 2.8 times (p=0.005) in the exercise group, whereas there was no change in the control group. Sclerostin index was decreased by 15.2% (p=0.031) in the exercise group and increased by 20.8% (p=0.028) in the control group. A change in the sclerostin index was an important predictor of a change in the vibration-induced normalised Root Mean Square of the semitendinosus muscle (R2=0.7, p=0.0001). Femoral neck bone mineral density was an important predictor of muscle strength gain (R2=0.26, p=0.035). CONCLUSION: This study indicates that bone tissue may have an effect on vibration-induced muscle strength gain and vibration-induced reflex muscle activity. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01310348.

A new method to determine reflex latency induced by high rate stimulation of the nervous system.

High rate stimulations of the neuromuscular system, such as continuous whole body vibration, tonic vibration reflex and high frequency electrical stimulation, are used in the physiological research with an increasing interest. In these studies, the neuronal circuitries underlying the reflex responses remain unclear due to the problem of determining the exact reflex latencies. We present a novel "cumulated average method" to determine the reflex latency during high rate stimulation of the nervous system which was proven to be significantly more accurate than the classical method. The classical method, cumulant density analysis, reveals the relationship between the two synchronously recorded signals as a function of the lag between the signals. The comparison of new method with the classical technique and their relative accuracy was tested using a computer simulation. In the simulated signals the EMG response latency was constructed to be exactly 40 ms. The new method accurately indicated the value of the simulated reflex latency (40 ms). However, the classical method showed that the lag time between the simulated triggers and the simulated signals was 49 ms. Simulation results illustrated that the cumulated average method is a reliable and more accurate method compared with the classical method. We therefore suggest that the new cumulated average method is able to determine the high rate stimulation induced reflex latencies more accurately than the classical method.

Somatosensory evoked potential findings in ankylosing spondylitis.

OBJECTIVE: Somatosensory evoked potential (SSEP) abnormalities were reported in patients with ankylosing spondylitis (AS). This study aimed to investigate SSEP abnormalities and its relation with clinical findings in AS patients. MATERIALS AND METHODS: The study included 26 patients with AS and 17 age-matched health volunteers (Control for SSEP). Median nerve SSEP findings were normal in all AS cases. RESULTS: However, delayed latency and/or very low amplitude of tibial nerve SSEP was found in 20 (76.9%) AS patients. There were significant correlations between tibial SSEP latency and disease duration (R=0.433 to 0.635). There was also an inverse correlation between tibial SSEP amplitude and disease duration (R=-0.429, p=0.047). Serum estradiol level, hip total bone mineral density, The Bath Ankylosing Spondylitis Functional Index (BASFI) score and Beck depression score were significantly lower in AS patients with SSEP abnormalities (37.3±10.8 pg/mL, 0.916±0.123 g/cm(2), 35.0±27.9, 12.8±8.4, respectively) than in AS patients without SSEP abnormalities (53.7±12.3 pg/mL, 1.103±0.197 g/cm(2), 64.8±15.5, 24.8±10.1, respectively). CONCLUSION: Significant inverse correlations between SSEP latencies and dehydroepiandrosterone sulphate (DHEAS) levels were found (R=-0.400 to -0.713). There were also significant inverse correlation between SSEP latencies and DHEAS/oestrogen index (R=-0.596 to -0.868), and between SSEP latencies and DHEAS/Progesterone index (R=-0.467 to -0.685). As a conclusion, this study indicates that tibial nerve SSEP abnormalities are common in patients with AS and there are significant correlations between clinical findings of AS and SSEP abnormalities.

Alexithymia and Self-Esteem in Patients with Ankylosing Spondylitis.

INTRODUCTION: Ankylosing spondylitis (AS), which has an unknown etiology, inflammatory disorder, characterized by inflammation of the spinal joints and adjacent structures. It has a negatif effect on all aspects of a patients's life: Physcally, psychologically and socially. The purpose of this study was to determine the effect of AS on self-esteem and alexithymia. METHOD: In this study, 50 patients from the department of physical therapy and rehabilitation with the diaognosis of AS who were under traetment and follow-up and 50 healty volunteers who matched for age and gender were taken. Toronto Alexithymia Scale (TAS), Beck Depression Inventory (BDI), Rosenberg Self-Esteem Scale (RSES), Beck Anxiety Inventory (BAI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were performed to both patients and control group. RESULTS: Compared to the control group, the anxiety and depression scores were higher in the patient group and the alexithymic characteristics were significantly higher, self-esteem scores were significantly lower in the patient group (p<.05). CONCLUSION: Like all the other inflammatory chronic diseases, depression and anxiety are commonly seen in AS patients. Alexithymai and self-esteem of these patients should be considered carefully. More studies are needed on this regard.

Effects of whole-body vibration on plasma sclerostin level in healthy women.

BACKGROUND/AIM: To determine whether plasma sclerostin levels are affected by applying whole-body vibration treatments. MATERIALS AND METHODS: Following a pilot study, the pretsent prospective, randomized, controlled single-blind study was performed on 16 healthy volunteer women (ages 20 to 40 years). Subjects were randomly divided into 2 groups, and whole-body vibration was applied to the treatment group but not to the controls. The plasma sclerostin levels were measured before the treatment and at the 10th minute after whole-body vibration on the 1st, 2nd, and 5th days of application. RESULTS: The plasma sclerostin level measured at 10 min after the whole-body vibration treatment increased 91% (P = 0.024) on the 1st day and decreased 31.5% (P = 0.03) on the 5th day in the whole-body vibration group. In the control group, there was no change in the plasma sclerostin level at any time. A progressive increase in baseline plasma sclerostin levels during the 5 days of vibration sessions was also found. CONCLUSION: Our study demonstrated that whole-body vibration can change plasma sclerostin levels, and that this change is detectable 10 min after whole-body vibration treatments.

Effects of osteocytes on vibration-induced reflex muscle activity in postmenopausal women.

BACKGROUND/AIM: To assess whether osteocytes have an effect on reflex myoelectrical activity during whole-body vibration (WBV) in postmenopausal women. MATERIALS AND METHODS: Participants were classified into 2 groups: the low bone mineral density (BMD) group (n = 37) and normal BMD group (n = 43). Hip BMD was measured using dual-energy X-ray absorptiometry. Surface electromyography data recorded from the adductor longus muscle were processed to obtain vibration-induced reflex myoelectrical activity. Changes in plasma sclerostin (SOST) levels with WBV were expressed as a standardized vibration-induced SOST index. RESULTS: The standardized vibration-induced SOST index was 1.03 ± 0.24 in the low BMD group and 0.99 ± 0.33 in the normal BMD group. For plasma SOST levels, no group-by-time interaction was found. The resting myoelectrical activities of adductor muscles increased significantly during WBV in both groups. However, there was no significant difference in the main effects of WBV on resting myoelectrical activity between the groups. The standardized vibration-induced plasma SOST index was found to be a significant independent predictor of the standardized vibration-induced reflex myoelectrical activity of the adductor muscle in both groups. CONCLUSION: This study suggests that osteocytes serve as mechanoreceptors of reflex electromyography during WBV.

Effects of sex steroids on serum sclerostin levels during the menstrual cycle.

BACKGROUND/AIMS: Previous studies on the effects of estrogen on sclerostin regulation were conducted in postmenopausal women in humans or animals following estrogen treatment or induced estrogen deficiency. The aim of this study was to evaluate the effects of sex hormones on serum sclerostin levels in premenopausal women with normal menstrual cycles. METHODS: A prospective observational clinical study. 80 voluntary premenopausal women were recruited for the study. Data from 31 patients were available for the statistical analysis. Serum sclerostin, free estradiol, free testosterone, and progesterone levels were measured during the menstruation, late follicular and mid-luteal phases. The unique protocol IDs were BEAH FTR-4 and NCT01418924 at ClinicalTrials.gov ID. RESULTS: Serum sclerostin values were 1.03 ± 0.58 ng/ml during the menstruation phase, 1.0 ± 0.36 ng/ml during the late follicular phase, and 1.18 ± 0.67 ng/ml during the mid-luteal phase (p = 0.543). There was no significant relationship between serum levels of sex steroids and sclerostin. CONCLUSIONS: Previous studies have not investigated the impact of sex hormone fluctuations on serum sclerostin levels during the menstrual cycle. The present study shows that serum sclerostin levels were not affected by sex steroids in premenopausal women with normal menstrual cycles.

Rectification of SEMG as a tool to demonstrate synchronous motor unit activity during vibration.

The use of surface electromyography (SEMG) in vibration studies is problematic since motion artifacts occupy the same frequency band with the SEMG signal containing information on synchronous motor unit activity. We hypothesize that using a harsher, 80-500 Hz band-pass filter and using rectification can help eliminate motion artifacts and provide a way to observe synchronous motor unit activity that is phase locked to vibration using SEMG recordings only. Multi Motor Unit (MMU) action potentials using intramuscular electrodes along with SEMG were recorded from the gastrocnemius medialis (GM) of six healthy male volunteers. Data were collected during whole body vibration, using vibration frequencies of 30 Hz, 35 Hz, 40 Hz or 50 Hz. A computer simulation was used to investigate the efficacy of filtering under different scenarios: with or without artifacts and/or motor unit synchronization. Our findings indicate that motor unit synchronization took place during WBV as verified by MMU recordings. A harsh filtering regimen along with rectification proved successful in demonstrating motor unit synchronization in SEMG recordings. Our findings were further supported by the results from the computer simulation, which indicated that filtering and rectification was efficient in discriminating motion artifacts from motor unit synchronization. We suggest that the proposed signal processing technique may provide a new methodology to evaluate the effects of vibration treatments using only SEMG. This is a major advantage, as this non-intrusive method is able to overcome movement artifacts and also indicate the synchronization of underlying motor units.

Normal range of spinal mobility for healthy young adult Turkish men.

Anthropometric characteristics may vary among human populations, especially with differences in race. The aim of the present study is to find normal values of some measures (chest expansion, Schober's test and modified Schober's test) frequently used in the assessment of patients with ankylosing spondylitis, in young adult Turkish men. Initial recruitment identified 2,925 healthy male participants aged 20-30 years, and the final study sample included 1,982 of them. Participants joined the research from all cities except one in Turkey. The measurements of chest expansion, Schober's test, and modified Schober's test were performed by the same researcher using a plastic measuring tape. The mean (±standard error) values of the chest expansion, Schober's test, and modified Schober's test were 6.11 (±0.02), 5.62 (±0.02), and 7.78 (±0.02) cm, respectively. The estimated normal lower bounds for chest expansion, Schober's test, and modified Schober's test may be between 3.71-3.86 cm, 3.86-3.97 cm, and 5.46-5.60 cm, respectively, for young adult Turkish men. No correlation was found between height and spinal mobility. The normal values for spinal mobility in this sample of healthy young adult Turkish men differed from those reported for other young adult male populations (chest expansion ≥5 cm, Schober's test >5 cm, modified Schober's test >7 cm). It is thus useful to consider nationality in interpreting results of spinal mobility tests.

Osteitis condensans ilii in differential diagnosis of patients with chronic low back pain: a review of the literature.

Osteitis condensans ilii (OCI) is a benign pathology causing chronic back and hip pain. Although the definitive cause is uncertain, mechanical stress is a significant factor in the development of the disease. Bilateral involvement of the sacroiliac joint is typical. We describe a case of unilateral OCI with unilateral sclerosis observed at radiography in a 34-year-old patient presenting with chronic back and hip pain, together with a review of the literature.

Shoulder pain and functional consequences: does it differ when it is at dominant side or not?

PURPOSE: The shoulder complex plays an integral role in the activities of daily living and the limitation of its function can greatly affect the patient. The aim of this study was to research the functional consequences of painful conditions in the shoulder region. METHODS: Sixty five adult patients with shoulder pain for longer than one month in duration were included to the study. Dominant hands of the patients were determined. The subjects were divided into two groups: shoulder pain at the dominant upper extremity (Group I) or the nondominant one (Group II). The subjects were evaluated for shoulder pain with visual analog scale (VAS), range of motion and functional status with the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. RESULTS: In Group I, DASH score was significantly correlated with the VAS score measuring the pain during activity (p< 0.0001, r=0,625). In Group II, no relationship between DASH score, VAS scores and any other parameters was detected. CONCLUSION: The most important parameter disturbing the daily living of a patient with shoulder disease is the pain at the shoulder of dominant extremity occurring in active movement.