H reflex excitability following voluntary muscle contraction of different duration.
The importance of the duration of contraction on the excitability of the motoneuronal pool was evaluated by measuring the H reflex from soleus muscle after short and long contractions at constant effort equal to 60% maximal voluntary contraction (MVC); the difference between the amplitude of H reflex at rest and after contraction of different duration was evaluated in 10 normal subjects and in one hemiparetic patient. The authors found a significant inhibition of H reflex after contraction of 10 seconds and after 40 seconds and a longer duration of the inhibition after 40 seconds. In the hemiparetic patient the H reflex did not show inhibition which suggests a possible reduction of the presynaptic inhibition, and a lack of modulation of the motoneuronal pool after contraction.
Dept. of Rehabilitation Medicine, Arcispedale S. Anna, Ferrara, Italy.
M
M
Manca
L
L
Cavazzini
S
S
Cavazza
T
T
Salvadori
D
D
DeGrandis
N
N
Basaglia
D000328:Adult; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006429:Hemiplegia / Q000503:physiopathology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D005082:Physical Exertion / Q000502:physiology*