Thank you Anke for your interest in how the tongue position affects movement. During embryological development the tissues that comprise the five muscles that fuse to form the tongue move into position along with muscles for opening snd closing the jaw and muscles for facial expression. Neurological development connects the tongue position with movements of the spine. Touching the tip of the tongue to the roof of the mouth behind the upper teeth facilitates spine extension. During single left leg jumping I press the tip of my tongue into the inside of the left cheek on the outside of the lower left back teeth in order to activate the left lateral pelvic stabilizers and other structures required for jumping and landing.
Jennifer, so glad you enjoyed the lower leg jumps on all fours. I discovered these jumps when searching for orientations that complement supine jumping. These novel jumps connect the feet and ankles with the whole torso and arms. You can use the cue 'strike a match with the sole of your foot' or 'kick your siting bones with your heels'.
I also wanted to add that I listen and don't watch workouts and this one I wish I had watch before I did. I highly recommend it with all of your videos as you are so eclectic with them as well as you have so much information, just watching is an education and will reduce any dumbass moves that will hurt you ( speaking from experience)