**3.3 Fibromyalgia**

Two studies investigated fibromyalgia patients (**Table 3**). In the larger study investigating the painful trapezius muscle of fibromyalgia patients, significantly higher interstitial concentrations of lactate and pyruvate were found compared to healthy controls (Gerdle et al., 2010). In the other study, the vastus lateralis muscle was investigated in eight patients with fibromyalgia and the authors reported no differences in concentrations of lactate compared to controls (McIver et al., 2006). It is unclear from this study if the vastus lateralis was habitually painful and/or painful at palpation (e.g., tender point examination). Moreover, no compensation for RR was done despite a relatively high flow rate.


\*Low flow rate associated with 100% relative recovery was defined as 0.3µl/min

Table 3. Studies of fibromyalgia. The results of the different substances are baseline data. Healthy controls are abbreviated as HC.
