(written from a Production point of view)
Established in the writers' second draft script of ENT: "Breaking the Ice", Sha'mura was a Vulcan martial art. It existed in ancient times, although its combat aspect was shunned while it developed since then. In the 22nd century, it was still practiced by Vulcans who valued its mental and physical discipline, though Sha'mura was less easy for Humans to do. Painful exercises were part of the point of this ancient martial art. The script's stage directions admitted, "The Vulcan exercise is harder than it looks."
T'Pol was practicing Sha'mura alone in the gym aboard Enterprise NX-01 at the start of the script's teaser, when Charles "Trip" Tucker arrived there. The script described T'Pol's movements as "swift and intense but at the same time fluid and restrained – like amped-up Tai Chi – showing off her strength and concentration." T'Pol was so deeply focused on her Sha'mura that she initially didn't notice Tucker had entered the gym. He was quite curious about the exercise. Though Tucker at first likened it to karate, he was quick to criticize the discipline when she told him it no longer involved an element of combat, Trip remarking, "Leave it to the Vulcans to take the fun out of everything."
At the end of the script, Tucker and T'Pol tried to practice some Sha'mura together, back in the gym. T'Pol tried to coach Trip through a series of Sha'mura positions but he clearly struggled with the martial art. After he fell, she instructed him to bend his knees, keep his back straight and his head up, then slowly turn at the waist. However, he found the exercise so difficult that they opted to try it again some other time.