Regular exercise of moderate intensity increases levels of IL-6 and can trigger release of inhibitory IL-1ra and Il-10 from local endothelial cells, thus causing an anti inflammatory response
Interleukin 6 IL-6 is shown to activate pain fibres , even in the absence of inflation.

Substance P is a substance that can contribute to peripheral inflammation.
Petersen AM, Pedersen BK. The role of IL-6 in mediating the anti inflammatory effects of exercise. Journal of Physiology and Pharmacology. 2006:57 (Suppl 10): 43-51
Teodorczyk-Injeyan Ja, Injeyan HS, Ruegg R. Spinal manipulative therapy reduces inflammatory cytokines but not substance P production in normal subjects. Journal of Manipulative and Physiological Therapeutics. 2006:29 (1): 14-21