BACKGROUND: People with symptomatic hypermobility have altered proprioception however, the origin of this is unclear and needs further investigation to target rehabilitation appropriately. The objective of this investigation was to explore the corticospinal and reflex control of quadriceps and see if it differed between three groups of people: those who have symptomatic hypermobility, asymptomatic hypermobility and normal flexibility.
METHODS: Using Transcranial Magnetic Stimulation (TMS) and electrical stimulation of peripheral nerves, motor evoked potentials (MEPs) and Hoffman (H) reflexes of quadriceps were evoked in the three groups of people. The threshold and latency of MEPs and the slope of the input-output curves and the amplitude of MEPs and H reflexes were compared across the groups.
RESULTS: The slope of the input-output curve created from MEPs as a result of TMS was steeper in people with symptomatic hypermobility when compared to asymptomatic and normally flexible people (p = 0.04). There were no other differences between the groups.
CONCLUSIONS: Corticospinal excitability and the excitability at the motoneurone pool are not likely candidates for the origin of proprioceptive loss in people with symptomatic hypermobility. This is discussed in the light of other work to suggest the receptor sitting in hypermobile connective tissue is a likely candidate. This suggests that treatment aimed at improving receptor responsiveness through increasing muscle tone, may be an effective rehabilitation strategy.

Enhanced physical performance following whole-body vibration (WBV) has been attributed to increased muscle activity; however, few studies have measured the mechanisms underlying these changes. The objective of this study was to measure the responsiveness of the Ia pathway as well as contractile properties in 16 young adults (24±2 years, eight men, eight women) following repeated bouts of acute WBV (45 Hz, 2 mm). Hoffman reflexes (H-reflex), compound muscle action potentials (M-wave), and twitch contractile properties were measured prior to and immediately following five 1-minute WBV exposures, and at 3, 5, 10, and 20 minute post-WBV. M-wave and H-reflex amplitudes decreased by 8% (P<.001) and by 46% (P<.05), respectively, whereas peak twitch torque decreased by 9% (P<.01) and rate of twitch torque development slowed 8% (P<.05). Percent voluntary activation and maximal plantar flexor torque were unchanged as a consequence of WBV (P>.05). In response to acute WBV, the root mean square of the soleus electromyography signal (EMGRMS ) increased by 8%, while the EMGRMS of the lateral gastrocnemius increased by 3% (P<.05). These data indicate that the responsiveness of the Ia pathway is diminished and contractile function is impaired immediately following WBV, and that the neural mechanisms underlying improved performance following WBV lie in alternative hypotheses possibly involving spindle disfacilitation or Golgi afferent modulation.

OBJECTIVE: This study aimed at determining the frequency of abnormal finger flexion, Hoffman\'s and extensor plantar (Babinski) response in healthy adults and to determine the sensitivity and specificity of these tests as markers of spinal cord compression in symptomatic patients.
METHODS: Patients attending the neurosurgery clinic with neck related complaints formed the case group. The control group consisted of consenting patient attenders and volunteers drawn from the students and faculty of our institute. All subjects underwent examination of the finger flexion, Hoffman\'s and plantar reflexes and an MRI as per standard protocol. The frequency of the reflexes in the control group, sensitivity and specificity of the reflexes to detect cord compression in the case group were computed.
RESULTS: The frequency of the reflexes in healthy controls were finger flexion - 1%, Hoffman\'s - 0.3% and Babinski sign - 0%. None of the controls with positive reflexes had any abnormality on MR imaging. A combination of the three reflexes had a sensitivity of 91.7%, specificity of 87.5%, PPV of 95.7% and NPV of 77.8% in detecting spinal cord compression.
CONCLUSIONS: A combination of finger flexion, Hoffman\'s and plantar reflexes could be used effectively as a marker of spinal cord compression in symptomatic individuals. They cannot, however, be depended on as screening tests in asymptomatic individuals.