Effects of vibration therapy on neuromuscular efficiency & features of the EMG signal based on endurance test

BackgroundVibration Therapy (VT) stimulate the muscle spindles, which in turn enhances its afferent activities.ObjectiveThe present study was designed to investigate the effect of VT at 23 and 35 Hz on muscle performance. The EMG features (six time-domain (TD) and four frequency-domain (FD)) and a new formula for computing neuromuscular performance were used as dependent variables to evaluate the effect of VT.MethodThe EMG recording was performed at 50% MVC during grip endurance test before and after VT. The EMG features were extracted out of raw EMG signals acquired from four forearm muscles, viz., flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi radialis brevis (ECRB); and extensor carpi ulnaris (ECU) in supine position. Fatigue assessments were evaluated based on the pattern of TD and FD features.ResultsStatistical analysis showed a significant difference in the effect of vibration exposure frequency on IEMG (p < 0.001), MAV (p = 0.041), SSI (p = 0.032), and WL (p < 0.001) of FCU muscle. In addition, the greatest increase in neuromuscular efficiency (NME) was observed in the performance of ECRB after 35 Hz of VT and ECU muscles after 23 Hz of VT.ConclusionsThe features of EMG signals could be used for fatigue analysis. However, the slope based on the median frequency regression line may be the best feature for fatigue assessment.     

振动性血管损伤的生物监测指标的实验研究

目的探讨振动性血管损伤的生物监测指标。方法将新西兰兔分为A组（接振强度3．04m／s^2）、B组（接振强度6．13m／s^2）、c组（接振强度12．26m／s^2）和1个对照组，分别于不同接振时间测定各组新西兰兔血浆内皮素、血管紧张素Ⅱ和一氧化氮的浓度。结果随接振时间的延长和接振强度的增高，血浆内皮素和血管紧张素Ⅱ的浓度有升高的趋势（P〈0．05，P〈0．01），而一氧化氮的浓度有降低的趋势（P〈0．05，P〈0．01）。结论振动导致内皮素、血管紧张素Ⅱ浓度的增高和一氧化氮浓度的降低，可能与振动性血管损伤有一定的关系，因此，选择内皮素、血管紧张素Ⅱ、一氧化氮作为振动性血管损伤的生物监测指标有一定意义。     

应力式振动对下肢肌力、骨密度、抗骨折能力及体成分的影响

[目的]探讨应力式振动治疗对骨质疏松的防治作用以及对体成分的影响。[方法]前瞻、开放性、随机对照研究,研究对象为符合入、排标准者178人,其中女性118名,男性60名,分为治疗组和空白对照组,治疗组使用振动治疗仪给予频率(32±3)Hz,加速度0.5～2.94m/s2的振动,每次10min,每周3次(隔日1次),共12周。主要观察指标:第2～4腰椎骨密度、左侧股骨颈骨密度、左下肢肌肉分布系数、左下肢肌肉力量,左侧股骨颈抗骨折能力、体重指数、体脂百分比、全身脂肪分布。[结果]治疗组与对照组比较,左侧股骨颈骨密度、左下肢肌肉力量,左侧股骨颈抗骨折能力均上升,差异有统计学意义(P﹤0.001),其余各项指标的变化差异无统计学意义(P﹥0.05)。[结论]应力式振动可有效防治下肢骨质疏松,对体成分无明显影响。     

局部振动对雄兔阴茎组织中eNOS VEGF ET-1蛋白表达的影响

目的探讨局部振动对雄兔阴茎组织中eNOS、VEGF、ET-1蛋白表达的影响。方法将新西兰兔随机分为A组(接振强度为3.02m/s2)、B组(接振强度为6.13m/s2)、C组(接振强度为12.26m/s2)和1个对照组,接振10、20、30d后,采用免疫组织化学SABC法检测阴茎组织中eNOS、VEGF、ET-1蛋白表达。结果与对照组相比较,A、B、C 3个试验组接振10、20、30d后,阴茎组织中VEGF、ET-1蛋白表达明显加强(P<0.05),eNOS蛋白表达明显降低(P<0.05)。结论局部振动通过上调阴茎组织中ET-1、VEGF和下调eNOS蛋白的表达影响性功能。     

FMRI mapping of the somatosensory cortex with vibratory stimuli. Is there a dependency on stimulus frequency?

Vibratory stimuli on the skin are mediated by two major receptors: Meissner corpuscles and Pacinian corpuscles. These receptors differ in properties such as density distribution, receptive field size, frequency sensitivity and depth of location. The cortical response to stimulation of these corpuscles can be tested by taking advantage of the differences in frequency discrimination of the receptors. Meissner corpuscles are most sensitive to frequencies around 10-50 Hz (flutter), while Pacinian corpuscles are most sensitive to high frequency (100-300 Hz) vibration. This study compared the neuronal responses (hemodynamic response) generated from vibratory stimuli of 35 Hz and 150 Hz with functional MRI. Group functional activation maps showed differences in the activation pattern for the two stimulus frequencies.     

振动对小鼠体内磺胺嘧啶（SD）分布的影响

为了研究振动对生物体内物质的耗散作用，本文用药代动力学的方法在振动频率为２０Ｈｚ，加速度为１．１ｇ与５０Ｈｚ，４．４ｇ的条件下分别测试了小鼠体内血、肝与肾组织中磺胺啮咬（ＳＤ）在１至９小时内的分布，结果表明：２０Ｈｚ实验组血中ＳＤ浓度峰伍比对照组提前３小时，在振动１小时时，小鼠体内血、肝与肾组织中ＳＤ含量均比对照组高，但振动３小时至９小时内，其含量均比对照组低，从管道气栓体外模拟实验与本文的研究可得到启示：在上述频率与强度条件下，振动对生物体可能有促进血液循环的作用。     

Interaction of ultrasound and amniotic liquid

The ultrasonic properties (velocity at 2·81 and 5·04 MHz, absorption in the range 1–15 MHz and vibration potential at 200 kHz) of amniotic liquid have been investigated. The results indicate that at physiological pH the absorption is essentially due to the proteins found in amniotic liquid, its vibration potential to the sodium chloride contained in this fluid while the velocity appears to be determined both by the proteins and sodium chloride. In the acid range (pH ～ 3) and alkaline range (pH ～ 9·6), proton transfer processes involving a low molecular weight component of amniotic liquid, in addition to those involving the proteins, contribute to the absorption of ultrasound by amniotic liquid.     

Occupational hand–arm vibration syndrome in Korea

Objectives: It is suspected that there is a large number of patients suffering from hand–arm vibration syndrome (HAVS) in Korea. However, no cases have been reported since 1992. This study was conducted to identify HAVS cases and determine the characteristics of the syndrome. Methods: In April 2001, the Busan, Ulsan, and Gyeong-Nam Province Occupational Disease Surveillance System (BUGODSS) was established to identify work-related HAVS and other occupational diseases. In the 2 years of this project, occupational physicians from five hospitals in these provinces collected information by way of interviews and questionnaires during mandatory occupational medical examinations. Among the initial 189 suspected HAVS cases, 58 volunteers were given cold-water provocation tests in order to diagnose the vascular component of the disorder. Results: One hundred fifty-four approximately occupational HAVS cases were identified from ca. 21,000 workers. One hundred fifty about of these cases were male. The cases were most often found in workers from the shipbuilding industry, and the grinder was the most common source of vibration exposure. Cases of sensorineural disorder (SD) were more common than cases of vascular disorder (VD). The mean values of the finger skin temperature and its recovery rate at 5 min and 10 min after cold-water provocation were significantly lower in the group with the VD than in the group with the SD. Conclusions: We identified 154 occupational HAVS cases, although no cases have been reported during the occupational medical examinations mandated by the state. The majority of the cases were in workers that used grinders in the shipbuilding industry. We determined that peripheral VD and peripheral SD can progress independently of each other. We conclude that exposure to hand-transmitted vibration (HTV) and HAVS cases are common in shipbuilding industry in Korea. The recovery rate of finger skin temperature after cold-water provocation is one of the useful methods for diagnosing the vascular component of HAVS.     

Segmental nerve conduction velocity in vibration-exposed shipyard workers

Objectives Segmental sensory nerve conduction velocity (SNCV) was measured from the wrists to the hands and digits of a population of vibration-exposed shipyard workers. This study was designed to investigate whether SNCV was selectively slowed in the fingers and whether a laboratory approach could be adapted for robust field use.Methods Wrist–palm, palm–proximal digit, and digital segments were determined from stimulation at the wrist with recording electrodes placed distally and adjusted to individual anatomy. The cohort was selected on the basis of current use of vibratory tools.Results Wrist–palm and digital segments were slower than palm–proximal digit segments for dominant and non-dominant hands and for both ulnar and median nerves. In the dominant-hand median nerve of participants with current exposure, the SNCV was 41.4 m/s (SD 8.0) for the wrist–palm segment, 50.8 (SD 9.5) for the palm segment, and 42.1 m/s (SD 9.3) for the digital segment. Temperature had an important effect on nerve conduction velocity but not equally across segments. Other explanatory variables had modest effect on SNCV.Conclusions Reduced SNCV in the digits may be a consequence of industrial exposure to vibration. Each sensory nerve segment appeared to have a different characteristic velocity and different pattern of association with skin temperature. There are differences between median and ulnar nerve segments, with potentially important consequences when standard distances are used to assess wrist–digit velocity.     

Individual factors and physical work load in relation to sensory thresholds in a middle-aged general population sample

The aim of this study was to explore individual and occupational factors possibly related to sensory thresholds in 484 middle-aged men and women from the general population. Multivariate analyses were performed using a linear model including eight covariates (age, body height, skin temperature, smoking habits, musculoskeletal symptoms during the last week before examination, isometric muscle strength, aerobic capacity, and average physical work load during the last 15 years). Men and women were considered separately in all analyses. Major findings were as follows: pressure pain thresholds increased with muscle strength; cold perception thresholds on the foot improved with increasing skin temperature; vibration and warm perception thresholds on the foot increased with age and body height; pressure pain threshold on the leg was decreased and vibration threshold on the hand was increased in women with musculoskeletal symptoms; pressure pain thresholds were slightly increased in men reporting long-lasting high physical work load. Significant sex differences were found for the majority of sensory thresholds, that is higher thresholds in men. However, body height was found to be more important than gender for differences in vibration and warm perception thresholds on the foot. Electronic Publication