Pain perception and the ability to modulate arising pain vary tremendously between individuals. It has been shown that endurance athletes possess higher pain tolerance thresholds and a greater effect of conditioned pain modulation than nonathletes, both indicating a more efficient system of endogenous pain inhibition. The aim of the present study was to focus on the neural mechanisms of pain processing in endurance athletes that have not been investigated yet. Therefore, we analyzed the pain processing of 18 male athletes and 19 healthy male nonathletes using functional magnetic resonance imaging. We found lower pain ratings in endurance athletes compared to nonathletes to physically identical painful stimulation. Furthermore, brain activations of athletes versus nonathletes during painful heat stimulation revealed reduced activation in several brain regions that are typically activated by nociceptive stimulation. This included the thalamus, primary and secondary somatosensory cortex, insula, anterior cingulate cortex, midcingulate cortex, dorsolateral prefrontal cortex, and brain stem (BS). Functional connectivity analyses revealed stronger network during painful heat stimulation in athletes between the analyzed brain regions except for connections with the BS that showed reduced functional connectivity in athletes. Post hoc correlation analyses revealed associations of the subject's fitness level and the brain activation strengths, subject's fitness level and functional connectivity, and brain activation strengths and functional connectivity. Together, our results demonstrate for the first time that endurance athletes do not only differ in behavioral variables compared to nonathletes, but also in the neural processing of pain elicited by noxious heat.

中文翻译：

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耐力运动员和非运动员之间疼痛处理的神经机制不同：功能连接磁共振成像研究

疼痛感知和调节疼痛的能力因人而异。已经表明，耐力运动员比非运动员具有更高的疼痛耐受阈值和更大的条件性疼痛调节效果，这两者都表明内源性疼痛抑制系统更有效。本研究的目的是关注尚未研究的耐力运动员疼痛处理的神经机制。因此，我们使用功能性磁共振成像分析了 18 名男性运动员和 19 名健康男性非运动员的疼痛处理。我们发现，与非运动员相比，在身体相同的疼痛刺激下，耐力运动员的疼痛等级较低。此外，在痛苦的热刺激期间，运动员与非运动员的大脑激活显示，通常由伤害性刺激激活的几个大脑区域的激活减少。这包括丘脑、初级和次级躯体感觉皮层、岛叶、前扣带皮层、中扣带皮层、背外侧前额叶皮层和脑干 (BS)。功能连接分析显示，在运动员痛苦的热刺激期间，所分析的大脑区域之间的网络更强，除了与 BS 的连接显示运动员的功能连接减少。事后相关分析揭示了受试者的健康水平和大脑激活强度、受试者的健康水平和功能连接以及大脑激活强度和功能连接之间的关联。一起，