When I was with Dagara tribe in Burkina Faso, they taught me how they do shamanic work. They tap on the soil, to connect with the earth, and they speak with ancestors. Earth is a connection with ancestors.
And these very same elements were present in many indigenous cultures around the world. Before Christianity wiped that out.*
In Gladiator, Maximus probably had very similar culture. We might seen him praying to his ancestors, represented by wooden figures. His connecting with Earth by touching the soil is also a form of prayer and connecting with ancestors.
You can try it too. Just mere touching the soil outdoors has a strong grounding effect = it can get us out of chaos in our heads, connecting us with our very core and nature, Earth, ancestors.
*) well not completely as we see... many of those who officialy converted still keep holding to their traditional shamanic work, but that's a different topic.