PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “REFLEX, TENDON”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1995

The influence of stretching and warm-up exercises on Achilles tendon reflex activity.

The aim of this study was to investigate the acute effects of prior exercise (warm-up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10-min warm-up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom-built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between-subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (-5%; P < 0.05), the force rise rate (-8%; P < 0.01), the half relaxation rate (-5%; N.S.), the EMG amplitudes (G, -16%; S, -17%; P < 0.01) and integrals (G, -15%; S, -18%; P < 0.01), and an increase in EMG latencies (G, +3%; S, +1%; P < 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (-2%; N.S.), the force rise rate and half relaxation rate increased by 8 and 12%, respectively (P < 0.01), and the impulse (force-time integral; -12%), EMG amplitudes (G, -20%; S, -23%; P < 0.01), integrals (G, -18%; S, -23%; P < 0.01) and latencies (G, -1%; S, -2%; P < 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm-up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance-enhancing effect.

Achilles Tendon↗
PubMed1981

Dependence of the Achilles tendon reflex on the excitability of spinal reflex pathways.

Muscle afferent activity from the triceps surae was recorded during experimentally induced alterations in amplitude of the Achilles tendon jerk. No changes in the neural afferent response to tendon percussion or in the background level of neural activity occurred when the reflex response was altered by discomfort, distraction, changes in attention, or changes in the rate of tendon percussion. Reinforcement of the Achilles tendon jerk by forceful contraction of the forearm muscles did not alter the relationship between intensity of the tendon tap and amplitude of the evoked neural afferent volley. Nevertheless, such maneuvers lowered the reflex threshold and raised reflex sensitivity so that a smaller afferent volley was required to produce a tendon jerk, and an increase in the afferent volley produced a disproportionately greater increase in reflex electromyographic activity than would have occurred at rest. Reinforcement maneuvers potentiated the H-reflex but did not alter the electrically induced afferent volley or the background level of neural activity. It is concluded that these changes in reflex responsiveness occurred through intrinsic spinal mechanisms independent of the fusimotor system.

Achilles Tendon↗