What would be the implications of the humans in my world having four additional limbs?

My world has one intelligent species, the Yuvolk. It is mostly humans with a few minor tweaks. From memory, they have a few additional brain cells (not too many more), they have an additional layer of muscles around their organs/brain/bones for extra protection, they have an additional set of limbs coming from their hips, their lumbar spine is fused into one solid bone rather than five vertebrae, they have larger mouths (and jaw muscles) and larger tongues, they have larger testicles, and the sole of their feet are larger in surface area, and their knees slightly higher up. (There are also changes to the world they live on, such as a ~30% stronger gravitational pull, but that will be in a separate post.) <br><br>I am most interested in the implications of the extra set of limbs, and the fused lumbar spine. These are both based on the assumption that we would/should evolve to have a 2nd set of arms, which would be super helpful/useful. The lumbar spine just to prevent back pain. <br><br>So, what are the implications of having an additional set of limbs, coming from the hips, with the lumbar spine fused together?<br><br>Feel free to consider other aspects of my world as well in your answer.