Search results for "Lengthening contraction"
showing 5 items of 5 documents
Changes in cortico-spinal excitability following uphill versus downhill treadmill exercise
2017
International audience; An acute bout of aerobic exercise induces neuroplasticity in the motor cortex. Moreover, paired associative stimulation (PAS) is known to induce neuroplasticity in M1. However, the possible influence of the type of exercise on the neuroplastic changes remains unknown. The present study investigated the effects of two different modes of muscle contraction produced during locomotor exercise on changes in corticospinal (CS) excitability. Subjects performed two 30-min treadmill exercises at an intensity corresponding to 60% of their maximal heart rate with either a +10% (uphill) or -10% (downhill) slope. These exercises were followed or not by paired associative stimulat…
Evoked responses to transcranial and electrical stimulation during isometric and lengthening contractions of the soleus muscle
2011
The aim of this study was to assess differences in motor control between isometric and lengthening contractions of the soleus muscle. Evoked responses to TMS (MEPs) and electrical stimulation of the peripheral nerve (H-reflexes) where recorded at rest and during isometric and lengthening contractions of the soleus muscle at 20%, 40%, 60% and 80% MVC. Torque and background EMG were averaged over a time window of 100ms prior to stimulation. MEPs were found to be significantly lower (P < 0.05) during lengthening contractions compared to isometric contractions at 40%, 60% and 80% MVC (10.95 ± 0.05 mV vs 9.93 ±0.06 mV ; 1.47 ± 0.07 mV vs 9.7 ± 0.08 mV; 11.48 ± 0.08 mV ± vs 10.14 ± 0.07 mV). The …
Stretch-reflex mechanical response to varying types of previous muscle activities
2002
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…
Specific modulation of corticospinal and spinal excitabilities during maximal voluntary isometric, shortening and lengthening contractions in synergi…
2011
Non-technical summary The neural control of muscle activity differs during voluntary shortening and lengthening contractions. In this paper, we show that the relative contribution of both cortical and spinal mechanisms to the modulation of neural activation is specific during lengthening contraction and differs between synergist muscles. Knowledge of spinal and corticospinal excitabilities modulations during shortening and lengthening muscle contraction improves our understanding of the processes that underlies the neural control of muscles during dynamic contractions.
Short-latency stretch reflex modulation in response to varying soleus muscle activities.
2002
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…