There was a study done that determined posture has a direct effect on a persons pain tolerance. Here’s a bit of the article:
“Mothers have been telling their children to stop slouching for ages. It turns out that mom was onto something and that poor posture not only makes a bad impression, but can actually make you physically weaker. According to a study by Scott Wiltermuth, assistant professor of management organization at the USC Marshall School of Business, and Vanessa K. Bohns, postdoctoral fellow at the J.L. Rotman School of Management at the University of Toronto, adopting dominant versus submissive postures actually decreases your sensitivity to pain.”