Thunder.

Shi Lang consumed the pill and began to channel the energy inside his body. The speed of the flow was not very high but it was mellow. The essence of the pill was soothing the cracks inside his meridians as if a sealant filling the cracks in a wall. 

The pain in his body was slowly receding. Injuries in the meridians caused immense pain, thankfully Shi Lang was a Terran cultivator as well, and that was why he was able to endure the torment, however, he did not tell anyone about this. The pain in his body was a constant, and that was the reason he was so irritated as well. 

The spirit essence moved through his body not only healing the meridians but also rejuvenating them. Once the spiritual energy has come in contact with the meridians if the supply is disrupted, the meridians become atrophic in nature, and without proper treatment, they will cause strong pain throughout the body.