Table 2.

Study characteristics.

Study	Sample Size	Population	Intervention Group	Comparison Group	Main outcomes and Measurement Tools	Follow-Up Period
Castien et al. [83]	80	Men and women aged 20–63 diagnosed with chronic TTH	Manual therapy treatment: mobilizations of the cervical and thoracic spine, postural correction and cervical stabilization exercises. 2 sessions/week, 9 sessions, 30 min/session.	No intervention	Intensity of pain: Numeric Rating Scale Headache frequency: personal diary headache duration personal diary	8 weeks 26 weeks
Ajimsha [84]	56	Men and women aged 18–50 diagnosed with TTH	TG1: Direct techniques for myofascial release in trapezius major, suboccipital, temporalis, neck flexors, mastoids muscles and Epicranial fascia. 2 sessions/week, 60 min/session. 12 weeks. TG2: Indirect techniques for myofascial release in skull base, posterior cervical musculature, hair, ears and facial musculature. 2 sessions/week, 60 min/session. 12 weeks.	No intervention	Headache frequency: personal diary	3 months
Da Silva et al. [85]	43	Pregnant women aged 18–39 diagnosed with TTH	Conventional acupuncture and additional points (trigger or painful points of splenius capitis, masseters and temporalis muscles) leaving the needles for 25 min. 2 session/week. 4 weeks	No intervention	Pain intensity (morning and evening): Numerical Rating Scale	3 months
Berggreen et al. [86]	38	Women aged 18–65 diagnosed with chronic TTH	Trigger Points treatment with frictions across or circulating in muscle fibers, ischemic compression, held from 30 to 60 s. Included muscles: trapezius (upper part), sternocleidomastoid, masseter, temporalis, medial and lateral pterygoid, anterior neck, facial, occipitofrontalis, splenius capitis and splenius cervicis, posterior cervical, and suboccipital muscles. 1 session/week. 10 weeks	No intervention	Pain intensity: Visual Analogical Scale	Pre-Post treatment
Espí-López et al. [87]	86	Men and women aged 18–65 diagnosed with TTH	TG1: Suboccipital soft tissue inhibition. 4 session/week. 4 weeks TG2: Occiput-atlas-axis manipulative treatment 4 session/week. 4 weeks TG3: G1 + G2 treatments combined. 4 session/week. 4 weeks.	Intragroup comparison	Pain Severity and headache frequency: Headache Disability Inventory	Pre-Post treatment
Moraska et al. [88]	62	Men and women aged 18–59 diagnosed with TTH	Massage: 15 min of myofascial of back, shoulders, chest, and neck; 20 min of trigger point release applied bilaterally to upper trapezius, suboccipital muscles, and both sternocleidomastoid; the final 10 min consisted of post-isometric relaxation directed at the right and left lateral cervical flexion, circular, or cross-fiber friction on the masseter, temporalis, and occipital-frontalis muscles, as well as gentle effleurage and petrissage on the neck and shoulders. 2 sessions/weeks. 6 weeks	Intragroup comparison	Pain intensity: Visual Analogical Scale. Frequency (episodes/week) Interview. Duration (hour/episode): Interview.	Pre-Post treatment and 1 month
Chassot et al. [89]	34	Women Aged 18–60 diagnosed with chronic TTH	Electroacupuncture: 16 acupuncture needles connected to an electro-stimulator for 30 min. 10 sessions. Twice/week. 5 weeks	Placebo	Pain intensity: visual analogical scale	Post treatment
Espí-López et al. [90]	102	Men and women aged 18–65 diagnosed with TTH	Occiput-atlas-axis manipulation (OAA) and soft tissue massage.1 session/week. 4 weeks	Massage 1 session/week. 4 weeks	Pain Severity and headache frequency: Headache Disability Inventory	Pre- Post treatment and 2 months
Ferragut-Garcías et al. [91]	97	Men and women aged 18–65 diagnosed with TTH	TG1: Soft tissues techniques.1 session/week.4 weeks TG2: Neural mobilization techniques 1 session/week.4 weeks TG3: Combined treatment involving soft tissue and neural mobilization techniques 1 session/week. 4 weeks	Placebo	Pain intensity: Visual analogical scale Headache frequency: personal diary	Post treatment and 1 month
Georgoudis et al. [92]	44	Men and women aged 18–65 diagnosed with TTH	Microwaves and myofascial release combined with acupuncture. 10 sessions.	Acupuncture	Pain intensity: Visual analogical scale	Pre-Post treatment
Pérez-Llanes et al. [93]	25	Men and women diagnosed with chronic TTH	Combined treatment with suboccipital muscle inhibition and interferential current. 2 sessions/week, 20 min/session.	Standard routine care (no interventions)	Intensity of pain: Numeric Rating Scale	4 weeks
Schiller et al. [94]	96	Men and women aged 18–65 diagnosed with chronic TTH	TG1: Acupuncture TG2: Medical training therapy (cardiovascular, strength-endurance, coordinative, proprioceptive, mobility and flexibility training), TG3: Combination of acupuncture and medical training. 6 weeks, 12 treatment units in decreasing frequency (3 sessions in weeks 1 and 2, 2 sessions in weeks 3 and 4, 1 session in weeks 5 and 6).	Standard routine care (no interventions)	Pain intensity: Verbal Rating Scale Frequency of headache: personal diary (days/month) Duration of headache: personal diary (hours/month) Frequency of headache medication intake: personal diary(days/month)	3 months 6 months
Corum et al. [95]	45	Men and women aged 19–48 diagnosed with TTH	TG1: Manipulation group: High-velocity low-amplitude (HVLA) manipulation plus exercise. 2 sessions/week for 4 weeks. TG2: Myofascial release group: suboccipital inhibition plus exercise. 2 sessions/week for 4 weeks.	Exercise intervention	Headache frequency: personal diary (days/2-week) Headache pain severity: Visual Analogical Scale	Pre-Post- treatment and 3 months
Gopichandran et al. [96]	169	Adult men and women diagnosed with chronic TTH	Progressive muscle relaxation (PMR) and deep breathing exercises. 12 weeks, 20 min,5 sessions/week, in the evening with an instruction booklet	Standard routine care (no interventions)	Pain intensity: Wong-Baker Faces Pain Scale	4 weeks 8 weeks 12 weeks
Runa et al. [97]	252	Men and women aged 18–75 diagnosed with anxiety and TTH	Warming acupuncture and moxibustion at temples combined with Deanxit (drug to improve depression and anxiety)	Warm acupuncture therapy (predominantly around the temple area)	Pain intensity: Visual Analogue Score Frequency of tension type headache: Interview Duration of tension type headache: Interview	Pre-Post treatment

TTH = Tension Type Headache, TG = Treatment Group.