they have been suggested as the 
 main cause of time off from work , reduced school performance , and low quality of life1,2,3 .
furthermore , they have led to personal , 
 familial and societal burdens , and significant healthcare problems globally4 , 5 . 

the prevalence of headaches is estimated at 13% of the united states population6 , 20% of the australians1 , and migraines are estimated at 11% , with tension - type 
 headaches at 78% of the population world - wide5 , 7 . according to the international headache society , headaches can generally be divided into 
 two categories which are primary and secondary headaches on the basis of the underlying 
 pathology8 .
primary headaches are not 
 associated with pre - existing medical conditions and there are three types : migraines , 
 tension - headaches and cluster - headaches6 . 

the remaining headache - sufferers 
 discontinue medications due to adverse side - effects or excessive use of abortive 
 medications .
these can lead to a refractory condition of medication overuse headache , which 
 means a consequent worsening of the headaches10 . as a result of these shortcomings ,
complementary and alternative 
 medicine has recently become common practice in current headache management6 , 10,11,12,13 .
yoga exercises are considered to be complementary and alternative medicine and are 
 practiced by approximately 5% of the adult population in the united states and 12% of 
 australians for alleviating headaches14 . 

yoga has been reported 
 as a safe and cost - effective intervention for managing pain1 , 14 .
evidence for the 
 efficacy of yoga exercise for a number of conditions is emerging .
a growing body of evidence 
 also supports the belief that yoga benefits physical and psychosocial health through the 
 mechanisms of down - regulation of the hypothalamic - pituitary - adrenal axis and the sympathetic 
 nervous system15,16,17 . as a result ,
yoga plays 
 an important role in reducing sympathetic activity , increasing parasympathetic activity , 
 improving quality of life , and decreasing pain levels18 , 19 .
as stated , there is 
 evidence of the benefit of yoga in reducing pain20 , 
 21 .
however , rigorous methodology and 
 quality of the evidence needs to be examined to establish whether or not we can assert yoga 
 can be used as a complementary and alternative therapy for sufferers of headaches22 , 23 .
therefore , the aim of this review was to assess the evidence for the 
 effectiveness of yoga exercises in the management of primary headaches .
the review was planned and conducted in accordance with the preferred reporting items for 
 systematic reviews and meta - analyses ( prisma ) guidelines24 , and the consolidated standards of reporting trials ( consort ) 
 guidelines for reporting parallel group randomized trials25 .
the cochrane library , cinahl , embase , psycinfo , pubmed , and 
 koreamed electronic databases were searched to identify rcts published between 1966 and 
 january 2015 .
all 
 potentially eligible studies were retrieved and the full texts of the articles were reviewed 
 to determine whether they met the following selection criteria . to be eligible , studies had to meet the following conditions .
1 ) population : participants 
 in the trials had to meet diagnostic criteria according to the international classification 
 of headache disorders , 3rd edition ( beta version ) published by the international headache 
 society 20138 ; primary headaches .
2 ) 
 intervention : randomized controlled trials were included that used yoga as an intervention 
 to review or reduce symptoms associated with headaches or migraines compared with no yoga . 

3 ) outcomes : primary outcomes were headache intensity , frequency , and duration ; secondary 
 outcomes were anxiety and depression scores , and symptomatic medication use .
quality 
 assessment of the articles was conducted using the critical appraisal , cochrane risk of bias 
 tool for rcts , which was recommended by the cochrane handbook for systematic reviews of 
 interventions26 .
the cochrane risk of 
 bias tool is a six - item list designed to assess sequence generation , allocation concealment , 
 blinding , incomplete outcome data , selective outcome reporting , and other potential sources 
 of bias .
each item is rated as  yes  ,  no  , or  unclear  .
according to the cochrane 
 handbook , the quality of clinical trials can be divided into three levels27 . when the study design fully meets the 
 preceding six criteria , it is considered a level , which means a low risk of bias .
b level is 
 assigned when one or more criteria are partly met , and when one or more criteria are not 
 met , the study is defined as c level , implying high risk of bias .
a total of 179 titles related to the search terms were screened . among these , there were 32 
 potential trials identified from chinal , 52 from koreamed , 43 from psycinfo and 52 from the 
 pubmed databases .
after the titles had been retrieved a total of 121 studies were excluded 
 either because they were duplicates or they were case studies , commentaries , review 
 articles , or had no target concepts , which means no headaches or migraines .
thirty - four potential trials were identified in the search 
 conducted in january 2015 .
thirty - four potentially relevant papers were retrieved for 
 evaluation of the full text .
after evaluation of the 34 full texts , 33 studies were 
 excluded , because 30 studies had no randomized trials and 3 studies had no full text of rct . 

. the characteristics of the included study are also presented ( table 1table 1.characteristics of included randomized controlled trialsauthor , year , location participantsinterventionsoutcome measuresmain resultsadverse events limitationsexperimental groupcontrol grouppopulation  sample sizen  ( n ; eg / cg)n  mean age ( years ; 
 eg / cg)n  drop out n ( % ) interventions  delivery method  duration 
 interventionistjohn et al.,2013 , india/ rajasthangeneral person72 ( 36/36)34.2 ( 34.3/34.2)7 
 ( 9.7)yoga postures , pranayama , kriya 60 min per day , 5 days 
 per week 3 months yoga therapistself - care education once a month 3 months handouts headache intensityheadache frequencyheadache 
 durationanxiety - depression scoressymptomatic medication use(p<0.001)(p<0.001)(p<0.001)(p<0.001)noneabsence of a placebo groups.no blinding.all 
 subjective outcome measures.no long - term follow - up dataeg : experimental group ; cg : control group ; n : number ) . flowchart of included studies through the literature searches eg : experimental group ; cg : control group ;
participants were recruited 
 from a headache clinic of the nmp medical research institute by advertising in local 
 newspapers .
the participants mean age 
 was 34.2  years , and they had primary headaches with migraines . the yoga program comprised yoga postures , breathing and pranayama , and kriya etc .
yoga 
 postures included physical exercises such the stretching of the neck , shoulder and back 
 muscles , followed by relaxation , toning , strengthening , and flexibility .
breathing and 
 pranayama means conscious breathing , kriya was practiced as a jalaneti ( nasal water 
 cleansing ) and kapalbhanti ( forced exhalations ) .
program length , frequency , and duration of 
 one trial was 60 minutes a day , 5 days per week for 3 months .
one trial was identified that compared a control group with a yoga intervention group and 
 evaluated the effect on headaches .
headache intensity ( p<0.001 ) , headache frequency ( p<0.001 ) , anxiety and 
 depression scores ( p<0.001 ) , and symptomatic medication use ( p<0.001 ) were 
 significantly lower in the intervention group then in the control group ( table 1 ) .
neither included trial reported data on adverse effects 
 of treatment ( table 1 ) .
assessments of each methodological quality item of the one included trial are described 
 ( table 2table 2.methodological quality summary of included trialsstudy , yearrandom allocationallocation concealmentblindingincomplete outcomeselective reportingother biasquality leveljohn et al .
the quality of the one trial was level b. + : criteria met ; - : criteria not met ; ? : unclear whether criteria were met
the purpose of this review was to assess the evidence for the effectiveness of yoga 
 interventions for primary headaches when compared to no yoga .
a meta - analysis combining 
 results from all the trials was not possible because only one study was identified .
its interventions included yoga poses , 
 pranayama , and kriya to manage headaches or migraines .
one trial reported a significant 
 decrease in headache intensity , headache frequency , anxiety and depression scores , and 
 symptomatic medication use in the trained group .
if required , participants were allowed to 
 take acute medication prescribed by neurologists during the trial .
the effects of the 
 medication could have diminished the efficacy of yoga exercises for alleviating headaches . 
 in spite of
both groups having received medication , reduction in the outcome of the yoga 
 group was significantly higher than that of the control group .
as stated in previous 
 studies , these results support yoga practice as a means of evidence - based positive 
 management of headaches or migraines20 , 22 , 28 , 29 .
the quality rating of the trial included 
 in this review had a moderate methodological quality , and the trial did not mention 
 blinding . however , no strong conclusion can be made due to the number of small trials and 
 other methodological considerations .
major strengths of this group of studies include the study , the use of randomization , and 
 the quality of measurement tools .
second , the trial did not mention blinding , lack of 
 which may have threatened the internal validity of the trial .
third , all the outcome 
 measurements were questioner - based and subjective ; objective parameters were lacking . 
 therefore , evidence - based research employing objective outcome parameters is needed to 
 identify the efficacy of integrated yoga therapy for headaches .
fourth , the trial had no 
 long - term follow - up data concerning the durability of the treatment effect . finally , the 
 generalizability of the findings was limited due to the number of small trials and their 
 partially limited quality . however ,
this one trial does provide a strong basis for future 
 studies and suggests that yoga exercises could provide a safe , cost - effective therapy for 
 the growing public health issue of headaches .
furthermore , this review contributes to the 
 development of knowledge in physical therapy about how sufferers with primary headaches can 
 manage themselves . in conclusion , although this review retrieved only a limited number of small trials , of 
 partially limited quality , its findings suggest that yoga practice can effectively alleviate 
 symptoms associated with primary headaches .
however further rigorous methodological and 
 high - quality rcts are needed to confirm and further comprehend the effects of standardized 
 yoga programs aiming to control pain intensity and frequency , symptoms , and medication use 
 etc .
 [ purpose ] to assess the evidence for the effectiveness of yoga exercises in the 
 management of headaches . 
 [ subjects and methods ] a search was conducted of six electronic 
 databases to identify randomized controlled trials ( rcts ) reporting the effects of yogic 
 intervention on headaches published in any language before january 2015 . 
 quality 
 assessment was conducted using the cochrane risk of bias tool . 
 [ results ] one potential 
 trial was identified and included in this review . 
 the quality critical appraisal indicated 
 a moderate risk of bias . 
 the available data could only be included as a narrative 
 description . 
 headache intensity and frequency , anxiety and depression scores , and 
 symptomatic medication use were significantly lower in the yoga group compared to the 
 control group . 
 [ conclusion ] there is evidence from one rct that yoga exercises may be 
 beneficial for headaches . 
 however , the findings should be interpreted with caution due to 
 the small number of rcts . 
 therefore , further rigorous methodological and high quality rcts 
 are required to investigate the hypothesis that yoga exercises alleviate headaches , and to 
 confirm and further comprehend the effects of standardized yoga programs on headaches . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION