Caffeine Attenuates Exacerbated Central Fatigue during Moderate-Intensity Cycling Exercise in Women with Fibromyalgia

To compare the development of fatigability during a moderate-intensity cycling exercise between women with fibromyalgia (FM) and control women (CON) after acute ingestion of caffeine and placebo.

Ten FM and 10 CON women performed a 30-min moderate-intensity cycling exercise 1 h after the ingestion of a capsule containing either caffeine or a placebo. Fatigability and its central and peripheral determinants were determined via changes from pre- to post-15 and post-30 min of exercise in maximal voluntary isometric contractions, voluntary activation (VA), and quadriceps potentiated twitch torque ( Qtw-pot ), respectively. Heart rate, muscle oxygen saturation, perceptive responses, mood state, localized and widespread pain, and sleepiness were also monitored during and after exercise.

There was a time versus group interaction for maximal voluntary isometric contraction and VA ( P < 0.001) but not for Qtw-pot ( P = 0.363), indicating a greater rate of fatigability development, mainly caused by central mechanisms, in the FM than in the CON group. There was also a main effect of condition for VA ( P = 0.011), indicating that caffeine attenuates central mechanisms of fatigability in both groups. Caffeine ingestion also increased muscle oxygenation, perceived vigor, and energy, and decreased leg muscle pain, sleepiness, and perceived fatigue in both groups. However, caffeine improved perceived pleasure/displeasure and exercise adherence likelihood only in the FM group.

Compared with CON, women with FM present a greater rate of fatigability during exercise, mainly of central origin. Caffeine seems to be a promising bioactive to counteract the central mechanisms of fatigability and improve the exercise experience among FM women.