***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background The mechanisms thorough which spinal manipulative therapy ( SMT ) exerts clinical effects are not established . A prior study has suggested a dorsal horn modulated effect ; however , the role of subject expectation was not considered . The purpose of the current study was to determine the effect of subject expectation on hypoalgesia associated with SMT . Methods Sixty healthy subjects agreed to participate and underwent quantitative sensory testing ( QST ) to their leg and low back . Next , participants were r and omly assigned to receive a positive , negative , or neutral expectation instructional set regarding the effects of a specific SMT technique on pain perception . Following the instructional set , all subjects received SMT and underwent repeat QST . Results No interaction ( p = 0.38 ) between group assignment and pain response was present in the lower extremity following SMT ; however , a main effect ( p < 0.01 ) for hypoalgesia was present . A significant interaction was present between change in pain perception and group assignment in the low back ( p = 0.01 ) with participants receiving a negative expectation instructional set demonstrating significant hyper algesia ( p < 0.01 ) . Conclusion The current study replicates prior findings of c- fiber mediated hypoalgesia in the lower extremity following SMT and this occurred regardless of expectation . A significant increase in pain perception occurred following SMT in the low back of participants receiving negative expectation suggesting a potential influence of expectation on SMT induced hypoalgesia in the body area to which the expectation is directed INTRODUCTION The aim of the study was to investigate the hypoalgesic effects of a single spinal manipulation treatment on acute inflammatory reactions and pain induced by cutaneous application of capsaicin . METHODS Twenty healthy subjects participated in the experiment , which consisted of 2 sessions . In both sessions , following control measurements , topical capsaicin was applied to the right or left forearm to induce cutaneous inflammatory reactions . The cream was removed after 20 minutes . Then subjects received either spinal manipulation treatment ( SMT ) or " nonspinal manipulation treatment " ( N-SMT ) , respectively . In control as well as pretreatment and posttreatment intervals , the following tests were performed : measurement of the areas of mechanical hyperalgesia and stroking allodynia , assessment of spontaneous pain , and measurement of blood flow . RESULTS The results confirmed that topical capsaicin induced inflammatory reactions based on occurrence of hyperalgesia and allodynia , augmented pain perception , and increased blood flow following capsaicin application compared with the control session . When compared with N-SMT , spontaneous pain was rated significantly lower post-SMT ( P < .014 ) . In addition , areas of both secondary hyperalgesia and allodynia decreased after SMT ( hyperalgesia : P < .007 ; allodynia : P < .003 ) . However , there was no significant treatment effect for local blood flow . CONCLUSION These results suggest hypoalgesic effects following a single SMT . As local vascular parameter was not affected by the single SMT , the hypoalgesic effects appear to be due to central mechanisms The treatment of lateral epicondylalgia , a widely-used model of musculoskeletal pain in the evaluation of many physical therapy treatments , remains somewhat of an enigma . The protagonists of a new treatment technique for lateral epicondylalgia report that it produces substantial and rapid pain relief , despite a lack of experimental evidence . A r and omized , double blind , placebo-controlled repeated- measures study evaluated the initial effect of this new treatment in 24 patients with unilateral , chronic lateral epicondylalgia .  Pain-free grip strength was assessed as an outcome measure before , during and after the application of the treatment , placebo and control conditions .  Pressure-pain thresholds were also measured before and after the application of treatment , placebo and control conditions . The results demonstrated a significant and substantial increase in pain-free grip strength of 58 % ( of the order of 60 N ) during treatment but not during placebo and control . In contrast , the 10 % change in pressure-pain threshold after treatment , although significantly greater than placebo and control , was substantially smaller than the change demonstrated for pain-free grip strength . This effect was only present in the affected limb . The selective and specific effect of this treatment technique provides a valuable insight into the physical modulation of musculoskeletal pain and requires further investigation Background Current evidence suggests that spinal manipulative therapy ( SMT ) is effective in the treatment of people with low back pain ( LBP ) ; however , the corresponding mechanisms are unknown . Hypoalgesia is associated with SMT and is suggestive of specific mechanisms . Objective The primary purpose of this study was to assess the immediate effects of SMT on thermal pain perception in people with LBP . A secondary purpose was to determine whether the result ing hypoalgesia was a local effect and whether psychological influences were associated with changes in pain perception . Design This study was a r and omized controlled trial . Setting A sample of convenience was recruited from community and outpatient clinics . Participants Thirty-six people ( 10 men , 26 women ) currently experiencing LBP participated in the study . The average age of the participants was 32.39 ( SD=12.63 ) years , and the average duration of LBP was 221.79 ( SD=365.37 ) weeks . Intervention and Measurements Baseline demographic and psychological measurements were obtained , followed by quantitative sensory testing to assess temporal summation and Aδ fiber – mediated pain perception . Next , participants were r and omly assigned to ride a stationary bicycle , perform low back extension exercises , or receive SMT . Finally , the same quantitative sensory testing protocol was reassessed to determine the immediate effects of each intervention on thermal pain sensitivity . Results Hypoalgesia to Aδ fiber – mediated pain perception was not observed . Group-dependent hypoalgesia of temporal summation specific to the lumbar innervated region was observed . Pair-wise comparisons indicated significant hypoalgesia in participants who received SMT , but not in those who rode a stationary bicycle or performed low back extension exercises . Psychological factors did not significantly correlate with changes in temporal summation in participants who received SMT . Limitations Only immediate effects of SMT were measured , so the authors are unable to comment on whether the inhibition of temporal summation is a lasting effect . Furthermore , the authors are unable to comment on the relationship between their findings and changes in clinical pain . Conclusions Inhibition of Aδ fiber – mediated pain perception was similar for all groups . However , inhibition of temporal summation was observed only in participants receiving SMT , suggesting a modulation of dorsal horn excitability that was observed primarily in the lumbar innervated area OBJECTIVE The purpose of this study was to investigate the effects of a spinal thrust manipulation directed to the upper cervical segments ( atlanto-occipital joint ) on active mouth opening and pressure pain sensitivity in a trigeminal nerve innervated region ( sphenoid bone ) in women with mechanical neck pain . METHODS Thirty-seven women , ages 21 to 50 years old ( mean age , 35 + /- 8 years ) with mechanical neck pain were recruited for this study . Participants were r and omly assigned into 1 of 2 groups as follows : an experimental group that received a spinal manipulation of the atlanto-occipital joint and a control group that received a manual contact placebo intervention . Outcomes collected were assessed pretreatment and 5 minutes posttreatment by an assessor blinded to the treatment allocation and included active mouth opening and pressure pain thresholds ( PPTs ) over both sides of the sphenoid bone . A 2-way repeated measures analysis of variance ( ANOVA ) with time ( pre-post ) as the within subjects variable and group ( control , experimental ) as the between subjects variable was used to examine the effects of the intervention . The hypothesis of interest was group-time interaction . RESULTS The ANOVA showed a significant effect for time ( F = 23.1 ; P < .001 ) and an interaction between group and time ( F = 37.7 ; P < .001 ) for active mouth opening as follows : the experimental group showed a greater improvement when compared to the control group . A large positive within-group effect size ( d > 1.5 ) for the experimental group , whereas a negative medium within-group effect size ( d = -0.5 ) for the control group were identified . The ANOVA showed a significant interaction between group and time ( F = 14.4 ; P < .001 ) for PPT levels at the sphenoid bone as follows : the experimental group showed a greater improvement when compared to the control group . A medium positive within-group effect size ( d = -0.5 ) for the experimental group , whereas a negative medium within-group effect size ( d = -0.5 ) for the control group was found . CONCLUSIONS Our findings suggest that the application of an atlantoaxial joint thrust manipulation result ed in an increase in active mouth opening and PPT over a trigeminal nerve distribution area ( sphenoid bone ) in women with mechanical neck pain BACKGROUND CONTEXT Spinal manipulative techniques ( SMT ) have shown clinical effectiveness in some patients with musculoskeletal pain . PURPOSE We performed the current experiment to test whether regional pain modulation is to be expected from thoracic SMT . STUDY DESIGN / SETTING R and omized experimental design performed in a university pain laboratory . OUTCOME MEASURES The primary outcome was experimental pain sensitivity in cervical and lumbar innervated area . METHODS Ninety healthy volunteers were r and omly assigned to receive one of three interventions ( SMT , exercise , or rest ) to the upper thoracic spine . Participants completed question naires about pain-related affect and expectations regarding each of the interventions . We collected experimental pain sensitivity measures of cervical and lumbar innervated areas before and immediately after r and omly assigned intervention . Mixed model analysis of covariance was used to test changes in measures of experimental pain sensitivity . RESULTS No interactions or intervention ( group ) effects were noted for pressure or A-delta-mediated thermal pain responses . Participants receiving SMT had greater reductions in temporal sensory summation ( TSS ) . CONCLUSIONS This present study indicates thoracic SMT that reduces TSS in healthy subjects . These findings extend our previous work in healthy and clinical subjects by indicating change in the nocioceptive afferent system occurred caudal to the region of SMT application . However , the duration of reduction in TSS is unknown , and more work needs to be completed in clinical population s to confirm the relevance of these findings OBJECTIVE The purpose of this study was to evaluate the pain/pressure threshold of selected myofascial points in subjects with chronic mechanical back pain after a single manipulation or mobilization . DESIGN The study design was a r and omized control trial . SETTING Chiropractic College outpatient clinic . PARTICIPANTS Thirty subjects aged 18 - 50 yr ( mean age 31 yr , SD = 7 yr ) with chronic mechanical low back pain ( mean duration of pain 74 months , SD = 83 months ) were r and omized into two groups . One group received a manipulation and the other received a mobilization . OUTCOME MEASURE Pain/pressure threshold of selected myofascial points were measured before , immediately after , and 15 and 30 min postintervention . RESULTS Sixteen patients were allocated to the manipulation group and 14 to the mobilization group . Repeated measured analysis of variance for all locations failed to show clinical or statistical significance ( p > .287 ) . The overall effect between treatments and the interaction between treatment and time was not significant ( p > .268 ) . CONCLUSION The absence of significant changes may be attributed to the selection of myofascial points , the instrument sensitivity to small changes , the differences in baseline measures and the absence of effect from one intervention OBJECTIVE The objective of this study was to determine whether mechanical force , manually-assisted ( MFMA ) spinal manipulative therapy ( SMT ) affects paraspinal muscle strength as assessed through use of surface electromyography ( sEMG ) . DESIGN Prospect i ve clinical trial comparing sEMG output in 1 active treatment group and 2 control groups . SETTING Outpatient chiropractic clinic , Phoenix , AZ . SUBJECTS Forty subjects with low back pain ( LBP ) participated in the study . Twenty patients with LBP ( 9 females and 11 males with a mean age of 35 years and 51 years , respectively ) and 20 age- and sex-matched sham-SMT/control LBP subjects ( 10 females and 10 males with a mean age of 40 years and 52 years , respectively ) were assessed . METHODS Twenty consecutive patients with LBP ( SMT treatment group ) performed maximum voluntary contraction ( MVC ) isometric trunk extensions while lying prone on a treatment table . Surface , linear-enveloped sEMG was recorded from the erector spinae musculature at L3 and L5 during a trunk extension procedure . Patients were then assessed through use of the Activator Methods Chiropractic Technique protocol , during which time they were treated through use of MFMA SMT . The MFMA SMT treatment was followed by a dynamic stiffness and algometry assessment , after which a second or post-MVC isometric trunk extension and sEMG assessment were performed . Another 20 consecutive subjects with LBP were assigned to one of two other groups , a sham-SMT group and a control group . The sham-SMT group underwent the same experimental protocol with the exception that the subjects received a sham-MFMA SMT and dynamic stiffness assessment . The control group subjects received no SMT treatment , stiffness assessment , or algometry assessment  intervention . Within-group analysis of MVC sEMG output ( pre-SMT vs post-SMT sEMG output ) and across-group analysis of MVC sEMG output ratio ( post-SMT sEMG/pre-SMT sEMG output ) during MVC was performed through use of a paired observations t test ( POTT ) and a robust analysis of variance ( RANOVA ) , respectively . MAIN OUTCOME MEASURES Surface , linear-enveloped EMG recordings during isometric MVC trunk extension were used as the primary outcome measure . RESULTS Nineteen of the 20 patients in the SMT treatment group showed a positive increase in sEMG output during MVC ( range , -9.7 % to 66.8 % ) after the 
    Output:
    
Meta- analysis was appropriate for studies examining the immediate effect of SMT on mechanical pressure pain threshold ( PPT ) .
SMT demonstrated a favorable effect over other interventions on increasing PPT .
Subgroup analysis showed a significant effect of SMT on increasing PPT at the remote sites of stimulus application supporting a potential central nervous system mechanism .