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.Key words: Skeletal muscle function, Gravitational physiology, Tonic vibration reflex     

Timothy Grass Pollen Induces Spatial Reorganisation of F-Actin and Loss of Junctional Integrity in Respiratory Cells

Inflammation - Grass pollens have been identified as mediators of respiratory distress, capable of exacerbating respiratory diseases including epidemic thunderstorm asthma (ETSA). It is...     

Cross-education of muscle strength: cross-training effects are not confined to untrained contralateral homologous muscle

The aim of this study was to evaluate whether electrical muscle stimulation (EMS) on dominant wrist flexors causes an increase in the muscle strength of the contralateral wrist extensors. Twenty-three healthy, young, adult men were included in this prospective, double-blind, controlled study. Participants were randomly allocated to the EMS group or Control group. Electrodes were placed over the flexor aspect of the right forearm in both groups. In the EMS group, passive wrist extension and (EMS) that caused powerful muscle contraction were simultaneously applied. In the Control group, a conventional mode of transcutaneous electrical nerve stimulation was applied without causing any contraction. A group effect (P=0.0001) and group-by-time interaction were found (P=0.0001) for both the wrist flexor and extensor muscles, but not group-by-time-by-arm interactions. This implies that the effect of the interventions was similar in both arms, but that the response was significantly larger in the EMS than in the Control group. The results of the current study suggest that cross-education is not confined to the untrained contralateral wrist flexors and that the strength increase may also be observed in the contralateral wrist extensors.     

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.     

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.Key words: Sclerostin, Whole-Body Vibration, Bone