## 3 Results
### Pain Intensity  
Seventeen studies assessed pain intensity in patients with headache; 8 of the studies included meta-analyses [8; 38; 39; 40; 41; 42; 43; 44], and the remaining 9 performed a qualitative synthesis [7; 29; 30; 31; 32; 33; 34; 35; 36].  
Interventions using AE with or without resistance exercise were an effective approach in patients with migraine or TTH in the short term [8; 29; 39]. Interventions based on manual therapy showed differences in favour of the Intervention group in patients with TTH [30; 32; 34; 38], and in populations that included patients with migraine, TTH and CGH in the short-term [33; 35; 40; 43] and at follow-up [35]. In patients with CGH, manual therapy showed positive results in the short-term [36; 44], but not in the medium- or long-term [44]. The combination of manual therapy and therapeutic exercise showed differences favouring the Intervention group in patients with migraine, TTH or CGH in the short-term [41] and medium-term [7; 31]. In one study, when comparing manual therapy with or without exercise and medication, they found significant differences in the short-term, but not in the long-term in patients with TTH [42].  
With regard to the quantitative analysis, the MMA of pain intensity in patients with migraine revealed significant differences using aerobic exercise in two meta-analyses [8; 41] (SMD = \(-\)1.16; 95% CI \(-\)1.90 to \(-\)0.41; \(p\) < 0.05) without evidence of heterogeneity (Q = 0.61, \(p\) = 0.44, (I\({}^{2}\) = 0%) (Figure 5).  
The MMA of pain intensity in patients with TTH treated by manual therapy or mixed treatment revealed significant differences in three [38; 40; 43] and two meta-analyses [41; 42], respectively (SMD = \(-\)0.83; 95% CI \(-\)1.47 to \(-\)0.19; \(p\) < 0.05 and SMD = \(-\)0.59; 95% CI \(-\)0.85 to \(-\)0.33; \(p\) < 0.05, respectively). There was evidence of heterogeneity in the analysis of manual therapy (Q = 6.39, \(p\) = 0.04, I\({}^{2}\) = 69%) but not in the case of mixed treatment (Q = 0.01, \(p\) = 0.91; I\({}^{2}\) = 0%) (Figures 6 and 7).  
Figure 5: Synthesis forest plot for pain intensity in patients with migraine treated with aerobic exercise. The forest plot summarizes the results of included studies (review size, standardized mean differences [SMDs] and weight). The small boxes with the squares represent the point estimate of the effect size and sample size. The lines on either side of the box represent a 95% confidence interval (CI).  
In the case of patients with CGH, the MMA of pain intensity also revealed significant differences in three meta-analyses including manual therapy or therapeutic exercise [41; 43; 44] (SMD = \(-\)0.49; 95% CI \(-\)0.86 to \(-\)0.12.33; \(p\) < 0.05) without evidence of heterogeneity according to [PERSON]'s Q statistical test (Q = 3.60, \(p\) = 0.16), but with heterogeneity according to \(1^{2}\) (\(1^{2}\) = 45%) (Figure 8).  
Figure 6: Synthesis forest plot for pain intensity in patients with tension-type headache treated with manual therapy. The forest plot summarizes the results of included studies (review size, standardized mean differences [SMDs] and weight). The small boxes with the squares represent the point estimate of the effect size and sample size. The lines on either side of the box represent a 95% confidence interval (CI).  
Figure 7: Synthesis forest plot for pain intensity in patients with tension-type headache and mixed intervention (manual therapy and/or therapeutic exercise). The forest plot summarizes the results of included studies (review size, standardized mean differences [SMDs] and weight). The small boxes with the squares represent the point estimate of the effect size and sample size. The lines on either side of the box represent a 95% confidence interval (CI).