0000000000598758
AUTHOR
K Ogiso
Stretch-reflex mechanical response to varying types of previous muscle activities
This study was designed to examine the effects of varying types of background muscle activity on the stretch-reflex mechanical response. A rapid stretch was applied to the calf muscles after an isometric (pre-ISO), shortening (pre-SHO) and lengthening contraction (pre-LEN) with several pre-contraction levels, respectively. The stretch perturbation was applied with the tibio-tarsal joint angle at 90 degrees. The ankle joint torque elicited by the stretch showed a first peak (non-reflex torque: NRT), a transient drop and a second peak (reflex torque: RT). The muscle activities before the stretch clearly influenced the stretch-reflex mechanical response. The NRT reached the largest peak with t…
Short-latency stretch reflex modulation in response to varying soleus muscle activities.
The current investigation examined the effect of various types of background muscle contractions on the short-latency stretch reflex (SLR) elicited from the soleus muscle while subjects were in a sitting position. A stretch was applied to the calf muscles while they performed an isometric (pre-ISO), shortening (pre-SHO) and lengthening contraction (pre-LEN) with several pre-contraction levels. The ankle was at a 90 degrees tibio-tarsal joint angle when the perturbation was applied. Subjects developed and maintained a given pre-load level, which was maintained at various percentages of the maximum voluntary isometric plantar flexion torque. This was performed at 80 degrees in pre-SHO, 90 deg…
Effects of effort and EMG levels on short-latency stretch reflex modulation after varying background muscle contractions.
It is known that the short-latency stretch reflex (SLSR) is modulated by the background muscle activity when it is elicited at matched torque levels. This study was designed to examine the effects of muscle contraction types before a stretch perturbation on SLSR in the human soleus muscle (SOL) when SLSR was elicited at the same levels of effort and at matched electromyographic (EMG) activity levels. A mechanical stretch perturbation was applied to the calf muscles when the ankle joint reached a ninety degree tibio-tarsal joint angle after the muscles performed an isometric (pre-ISO), shortening (pre-SHO) and lengthening contraction (pre-LEN). Subjects were seated on an ankle ergometer chai…