What does h-reflex mean?

Definitions for h-reflex
h-reflex

This dictionary definitions page includes all the possible meanings, example usage and translations of the word h-reflex.

Wikipedia

  1. H-reflex

    The H-reflex (or Hoffmann's reflex) is a reflectory reaction of muscles after electrical stimulation of sensory fibers (Ia afferents stemming from muscle spindles) in their innervating nerves (for example, those located behind the knee). The H-reflex test is performed using an electric stimulator, which gives usually a square-wave current of short duration and small amplitude (higher stimulations might involve alpha fibers, causing an F-wave, compromising the results), and an EMG set, to record the muscle response. That response is usually a clear wave, called H-wave, 28-35 ms after the stimulus, not to be confused with an F-wave. An M-wave, an early response, occurs 3-6 ms after the onset of stimulation. The H and F-waves are later responses. As the stimulus increases, the amplitude of the F-wave increases only slightly, and the H-wave decreases, and at supramaximal stimulus, the H-wave will disappear. The M-wave does the opposite of the H-wave. As the stimulus increases the M-wave increases. There is a point of minimal stimulus where the M-wave is absent and the H-wave is maximal. H-reflex is analogous to the mechanically induced spinal stretch reflex (for example, knee jerk reflex). "The primary difference between the H-reflex and the spinal stretch reflex is that the H-reflex bypasses the muscle spindle, and, therefore, is a valuable tool in assessing modulation of monosynaptic reflex activity in the spinal cord." Although stretch reflex gives just qualitative information about muscle spindles and reflex arc activity, if the purpose of the test is to compare performances from different subjects, H-reflex should be used. In that case, in fact, latencies (ms) and amplitudes (mV) of H-wave can be compared. H-reflex amplitudes measured by EMG are shown to decrease significantly with applied pressure such as massage and tapping to the cited muscle. The amount of decrease seems to be dependent on the force of the pressure, with higher pressures resulting in lower H-reflex amplitudes. H-reflex levels return to baseline immediately after pressure is released except in high pressure cases which had baseline levels returned within the first 10 seconds.After about 5 days in zero gravity, for instance in orbit around Earth, the h-reflex diminishes significantly. It is generally assumed that this is due to a marked reduction in the excitability of the spinal cord in zero gravity. Once back on Earth, a marked recovery occurs during the first day, but it can take up to 10 days to return to normal. The H-reflex was the first medical experiment completed on the International Space Station.

Wikidata

  1. H-reflex

    The H-reflex is a reflectory reaction of muscles after electrical stimulation of sensory fibers in their innervating nerves. The H-reflex test is performed using an electric stimulator, which gives usually a square-wave current of short duration and small amplitude, and an EMG set, to record the muscle response. That response is usually a clear wave, called H-wave, 28-35 ms after the stimulus, not to be confused with an F-wave. An M-wave, an early response, occurs 3-6 ms after the onset of stimulation. The H and F-waves are later responses. As the stimulus increases, the amplitude of the F-wave increases only slightly, and the H-wave decreases, and at supramaximal stimulus, the H-wave will disappear. The M-wave does the opposite of the H-wave. As the stimulus increases the M-wave increases. There is a point of minimal stimulus where the M-wave is absent and the H-wave is maximal. H-reflex is analogous to the mechanically induced spinal stretch reflex. "The primary difference between the H-reflex and the spinal stretch reflex is that the H-reflex bypasses the muscle spindle, and, therefore, is a valuable tool in assessing modulation of monosynaptic reflex activity in the spinal cord." Although stretch reflex gives just qualitative information about muscle spindles and reflex arch activity; if the purpose of the test to compare performances from different subjects, H-reflex should be used. In that case, in fact, latencies and amplitudes of H-wave can be compared.

U.S. National Library of Medicine

  1. H-Reflex

    A monosynaptic reflex elicited by stimulating a nerve, particularly the tibial nerve, with an electric shock.

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Numerology

  1. Chaldean Numerology

    The numerical value of h-reflex in Chaldean Numerology is: 6

  2. Pythagorean Numerology

    The numerical value of h-reflex in Pythagorean Numerology is: 6

Examples of h-reflex in a Sentence

  1. Scott Caulfield:

    Jumping falls into a type of exercise we call plyometrics, these exercises involve quicker, shorter motions that stimulate the stretch reflex. That reflex is responsible for explosive movement, like an outfielder reacting to a fly ball.

  2. Darius Paduch:

    It’s due to the vagal reflex, in which a nerve signal from your testicles travels up your spinal cord and brain stem and activates the nausea and vomiting centers in your brain.

  3. Mark Zuckerberg:

    I'll have to understand what they actually would intend to do, but in general I think a government choosing to censor a platform because they're worried about censorship doesn't exactly strike me as the right reflex there.

  4. Tim Soutphommasane:

    Obviously that's no longer in place, but the sentiment remains there under the surface. There remains a strong reflex of closing down our borders to any perceived threat.

  5. Obdulia Sanchez:

    Trust me, it’s like a reflex, everybody does it. Everybody does. They take Snapchats. Why not? People take video of them in cars like all the time.


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"h-reflex." Definitions.net. STANDS4 LLC, 2024. Web. 19 Mar. 2024. <https://www.definitions.net/definition/h-reflex>.

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