You can find this exercise on page 206 of the book Synergistic Golf.
Exercise Type: STRENGTH
Exercise Category: CHEST, SHOULDERS, STRENGTH
Start in basic pushup position. Whether knees remain down or up, keep a straight line between head, shoulders, spine, hips, and knees. Place hands one hand width wider than shoulders and sternum between thumbs. Keeping spine and abdominals tight, lower body straight down to the floor by bending at elbows and return to straight arms. Repeat 10x for 3 sets. Inhale as you lower down, exhale on the return push back up.