High training volume in any sport will lead to overuse injuries and muscular imbalances, and Muay Thai is no exception. It’s true, you can really have too much of a good thing! Fighting posture is designed to defend vulnerable parts of your body against imminent attack, not promote long term health. And Thai boxers spend a significant amount of time hunched forward in a fighting stance, throwing a disproportionate amount of horizontal extension movements while punching or even holding pads for training partners. However, intelligent supplemental training can counteract these muscular imbalances, so don’t go jacking it all in just yet...
heatrick.com/2012/11/19/is-muay-thai-bad-for-posture/