Generally, during their spars and training, except mandated, both parties were not allowed to empower their bodies with spirit energy to boost their physical capabilities, so they fought purely based on their physical capabilities.
This was one of the reasons why Khal didn't take much interest in guiding Desmond, the young man Ingrid introduced to the family. He couldn't even develop his physical strength properly. It seemed to be a problem rooted in humans of this lower world, as for whatever reason and laws guiding their world, they didn't seem to be able to increase their body's natural strengths past a certain level and could only reach a certain level before it becomes impossible to go past that limit.
