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- Björklund, Martin, et al.
(författare)
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Muscle stretch-induced modulation of noxiously activated dorsal horn neurons of feline spinal cord.
- 2004
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Ingår i: Neuroscience research. - : Elsevier BV. - 0168-0102 .- 1872-8111. ; 48:2, s. 175-184
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Tidskriftsartikel (refereegranskat)abstract
- The present work was designed to check for the possibility of interactions between mechanical innocuous and chemically induced noxious muscle afferent inputs on discharge behavior of nociceptive superficial dorsal horn neurons (SDHNs) of the spinal cord in decerebrated cats. The innocuous and noxious stimuli were applied separately and in combination, so that the effects of the innocuous stimulus on nociceptive processing could be evaluated. The innocuous stimulus consisted of ramp-and-hold stretches of the gastrocnemius muscles, whereas the noxious stimulus consisted of i.a. injections of bradykinin (BK; 0.5-1 ml, 50 microg/ml) into the arterial circulation of same muscles. Only neurons up to approximately 1mm depth and those that responded to noxious pinch of the gastrocnemius muscles were selected for further analysis. The activity of 16 dorsal horn neurons was recorded extracellularly with high-impedance glass microelectrodes, out of which seven responded to stretch, while 12 neurons responded to bradykinin injections. The bradykinin injections induced three types of responses: excitatory, inhibitory and mixed. The majority of the neurons that showed excitatory and mixed responses to bradykinin were also influenced by stretches applied directly after the bradykinin injection. In these neurons, the stretch usually counteracted the bradykinin-induced response, i.e. shortening and reducing bradykinin-induced excitation and re-exciting the cells after bradykinin-induced inhibition. The mechanism of the stretch modulation is proposed to reside in a segmental spinal control of the nociceptive transmission.
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- Björklund, Martin, et al.
(författare)
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Sensory adaptation after a 2-week stretching regimen of the rectus femoris muscle
- 2001
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Ingår i: Archives of Physical Medicine and Rehabilitation. - : Elsevier BV. - 0003-9993 .- 1532-821X. ; 82:9, s. 1245-1250
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the effects of a muscle stretching regimen for the rectus femoris muscle on subjective stretch sensation and range of motion (ROM). DESIGN: A 2 x 2 crossover design comprising 2 treatments and 2 intervention periods. SETTING: A military base in Sweden. PARTICIPANTS: A volunteer sample of 29 male military conscripts divided into 2 groups, with each group subjected to both experimental and control treatments at different time periods. INTERVENTION: Two weeks of supervised stretching (4 times/wk) of the rectus femoris muscle (experimental treatment) and the calf muscles (control treatment). MAIN OUTCOME MEASURES: Subjective rating of the stretch sensation for the anterior aspect of the thigh determined on a category ratio scale. Passive knee flexion ROM determined on each test with the same applied torque, specific for each subject. RESULTS: An additive analysis of variance revealed that the stretch sensation after the experimental treatment was decreased, compared with the control treatment (p <.01). The knee flexion, however, remained the same regardless of the treatment. CONCLUSION: Sensory adaptation seems to be an important mechanistic factor in the effect stretching has on ROM changes. The lack of change in knee flexion suggests that the stretching, as performed in this study, did not influence stiffness of the rectus femoris muscle. Sensory adaptation may also be an underlying mechanism in the alleviating effect of stretching when applied to tired, tender, and painful muscles.
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