The Anatomy of the Curve
The heart in the trend is a two author shape, the hand writes the first half and the body writes the second, and the body's half is the part that varies from person to person, and it is the part the test measures. The C shaped hand is the easy component, the knuckles curve over, the thumb drops below, and the opening of the C becomes the left lobe of the heart. The right lobe, the side that completes the figure, is not in your hand at all, it is the outward line of your waist, and that line is drawn by two things working together, the obliques on the side you are pressing into, and the tilt of the hip underneath them. Get the curve of one and the angle of the other wrong and the right lobe goes blunt, and the shape stops being a heart somewhere around a rhombus.
Why Some People Need a Friend
The friend who pulls your waist is not a joke, it is a physical fact about the move. The obliques can shorten the side of the torso, which tightens the line, but the resting position of most people's hip sits under the shape, so the curve needs to move slightly outward and upward at the same time, and the obliques alone can do the tightening, they cannot do the lift, the lift is the hip tilt, and the tilt is the hard dial, that is the one the later rounds of the test push furthest. A friend pulling your waist is doing the hip tilt mechanically for you, the pull supplies the outward vector that the standing person cannot generate solo, which is why the skits where the pull happens are the clips that outpulled the solo attempts, the pull is the moment the shape actually lands. For the people whose hip line is already high and the obliques already tight the solo version works fine, and that is the reason the trend has a visible two cast of performers, the effortless ones, and the ones who need a friend and do not pretend otherwise.
The Three Dials the Test Uses
The game translates the anatomy into three sliders, and the three sliders are the three dials of the move. Waist curve, how hard the side of the torso bends inward then out, the obliques dial. Hand angle, how far the C of the hand leans into the waist, the knuckle dial, too much angle and the C becomes a hook, too little and it flattens. Hip tilt, the upward vector that lifts the whole shape into the air of the heart, the pull dial, the one a friend supplies in the skits. Each round of the test gives you a target set for all three, the easy rounds want a modest curve and a comfortable hand, and the hard rounds want the curve pushed near its limit with the hand leaning in tight and the hip lifted the most, which is exactly the spot where the solo version breaks and the card quietly tells you a friend might help.