When I started working on downward transitions using my thighs and firming my stomach I did them on exhale and made a grunting sound. This helped me to engage my inner stomach muscle without thinking too much about it. At that time my transversus abdominis (most inner stomach muscle which fibers lay horizontally) were not as efficient as they now. My horse connected that sound with the request for a downward transition. Now I can produce almost non-audible low grunting sound and my horse responds. I do not use reins, I only close my fingers. I even think of pushing my hands forward without actually advancing them. That really helped me to get rid of my bad habit of taking reins toward my body during downward transitions. Before I did it almost unconsciously. His trot-walk transitions are the best, like a car with good brakes he makes them quickly, smoothly and in balance. I sometimes ride them just for fun to feel the flow and engagement and asking them from extended trot, going uphill, downhill. He has built a beautiful topline doing these transitions.