who tenses his arms and hard-slaps the ground
I admire how you steadfastly hold to your opinion. GRRRR!
OK - the arm is not tense during the slap. Another poster mentioned transmitting energy From the falling body To the ground. Can you see that it is:
1. valid from physical standpoint
2. valid from physiological standpoint
3. possibly ki training?
or just a joke my teacher was playing on me?