Domain: Humanities and Social Sciences — Sport
Target concept: Front Lever on Rings in Gymnastics: The front lever on rings requires the athlete to assume a horizontal body position, labeled as the ring front lever, with arms fully extended and shoulder-width apart, and the body parallel to the ground, featuring a distinctive posture.

Video generation prompt: A gymnast grips two suspended rings with arms fully extended and roughly shoulder-width apart, then leans the torso forward and down, lifting the hips and legs to follow, attempting to bring the whole body into a horizontal line parallel to the ground to hold a ring front lever.

Evaluation guide:
(i) Target concept: Static mechanical equilibrium of a human body held horizontally beside gymnastic rings, achieved by straight-arm shoulder/lat/triceps force combined with whole-body isometric bracing that keeps the torso, hips, and legs aligned as one rigid horizontal lever arm.
Minimum mechanism: Rings must be rigidly anchored overhead with no sway; the gymnast's arms stay locked straight and roughly shoulder-width apart throughout (they do not spread outward into a wide T); the torso rotates about the shoulder joints away from vertical, and the hips and legs lift in coordination with the torso rather than trailing loosely or dropping; abdominal and hip-flexor musculature isometrically resists the hips and legs sagging below the line drawn from shoulders to feet, so the body settles into one straight line parallel to the ground.
(ii) Storyline: Frame 1-2: gymnast grips both rings and supports the body with arms straight, torso still upright → Frame 3-4: torso begins leaning forward and down from the shoulders, departing from vertical, while the arms remain straight and close together → Frame 5-6: torso continues rotating toward horizontal, hips and legs rising to stay in line with the shoulders rather than hanging down → Frame 7-8: body approaches a single horizontal line, arms still fully extended and roughly shoulder-width apart → Frame 9-10: horizontal ring front lever reached: torso, hips, and legs form one straight line parallel to the ground, arms fully extended and shoulder-width apart supporting the entire body weight. Camera must show a side or 3/4 view so the horizontal line of the body is clearly visible (not a straight-on front view along the body's long axis, and not top-down only); the gymnast's full body and both rings must remain continuously visible without occlusion; no cutaways or camera repositioning.

Manual:
Experimental Procedure
1. Gymnast grips both suspended rings with a firm overhand grip and supports the body with arms fully straight, roughly shoulder-width apart.
2. Keeping the arms locked straight and close together, the gymnast leans the torso forward and down, rotating the body about the shoulder joints while lifting the hips and legs to follow rather than letting them hang.
3. The torso, hips, and legs come into a single straight line parallel to the ground, arms remaining fully extended and roughly shoulder-width apart, supporting the entire body weight in a static horizontal hold.
Observation of Experimental Phenomena
- Rings remain fixed overhead with no lateral sway.
- Arms stay fully extended and roughly shoulder-width apart throughout, never spreading outward into a wide T shape.
- Torso, hips, and legs align into one rigid horizontal line parallel to the ground, with no sagging at the hips or bending at the knees.
- The gymnast's body stays suspended above the ground with no contact other than the hands on the rings.
Summary of Experimental Principles
This horizontal hold is known as the front lever (on rings, sometimes called the ring front lever): it requires the arms to generate enough straight-arm shoulder, lat, and triceps force to support the full body weight without bending, while the torso, hips, and legs act together as one long horizontal lever arm about the shoulder joints — a lever that abdominal and hip-flexor musculature must isometrically brace to keep from sagging. This is mechanically distinct from ring holds where the arms extend horizontally out to the sides in a wide T-shape, such as the Iron Cross (torso vertical, arms out to the sides) or the Maltese (torso horizontal, arms out to the sides); in the front lever, the arms stay close together at roughly shoulder width directly beneath the body, and it is the whole body — not the arms — that forms the horizontal line.

Prompt Grounding rubric:
level_1: No rings visible; no human figure present; or figure not grasping any apparatus; or arms not extended at all.
level_2: Rings are present and a human figure is present, but the figure does not grasp the rings; or grasps rings but arms remain bent; or body is upright/squatting/hanging without horizontal extension.
level_3: Figure grips the rings with arms fully straight and roughly shoulder-width apart, and the torso begins rotating away from vertical toward horizontal while the hips and legs start to lift and follow; however, the arms are not fully straight, OR the arms visibly spread outward away from the body instead of staying close together, OR the torso/hips/legs are not yet aligned into a single line parallel to the ground.
level_4: Figure grips the rings with arms fully straight and roughly shoulder-width apart (not spread outward); torso, hips, and legs are aligned into a single horizontal line parallel to the ground, but one of the following occurs: slight asymmetry between the two arms, a slight sag or bend at the hips, or a transient elbow bend during the transition.
level_5: Figure grips the rings with arms fully straight and symmetrically positioned roughly shoulder-width apart (never spreading outward into a T shape); torso, hips, and legs form one perfectly straight horizontal line parallel to the ground throughout the entire visible duration; no elbow flexion, no sag at the hips, no asymmetry in limb positioning.

Scientific and Causal Correctness rubric:
level_1: No causal sequence linking grip → torso rotation → hip/leg lift → horizontal position; or the horizontal posture appears without any visible torso rotation away from vertical; or the arms visibly spread outward to the sides instead of staying at shoulder width.
level_2: Grip and straight-arm support occur, but the torso does not rotate away from vertical toward horizontal; or the torso leans while the hips and legs fail to lift and follow, so the body never forms a single line.
level_3: Grip → torso rotation → hips/legs lifting to follow → horizontal body sequence is visually present, but the horizontal state is not sustained long enough to confirm static support (i.e., it immediately sags or rises); or the hips/legs visibly sag below the shoulder-to-feet line after the horizontal position is reached.
level_4: Full causal sequence is visible: grip → torso rotates from vertical toward horizontal → hips and legs lift in coordination with the torso → attainment of a single straight horizontal line; horizontal state is maintained for an observable duration; however, one of: the arms drift outward from shoulder width, the hips sag slightly, or the torso shows slight curvature.
level_5: Causal chain is unbroken and unambiguous: grip is established with arms already straight; the torso rotates smoothly away from vertical while the arms remain straight and close together at shoulder width (never spreading outward); the hips and legs lift in step with the torso so the body settles into one continuous straight horizontal line with no sag, no drift, no correction, no collapse.

Spatiotemporal Consistency rubric:
level_1: Figure or rings teleport between frames; sudden disappearance/reappearance; abrupt lighting shift (e.g., shadow vanishes then reappears); rings detach from ceiling or float; body parts distort or stretch unnaturally.
level_2: Minor spatial discontinuities: brief flicker in ring visibility; momentary occlusion that breaks continuity of arm trajectory; inconsistent shadow direction across frames; or one ring rotates independently while the other stays fixed.
level_3: All objects maintain consistent spatial relationships: rings remain fixed in overhead position; figure maintains grounded/fixed suspension point; arms move continuously without jumps; torso orientation changes smoothly; no structural warping, but minor inter-frame jitter in limb endpoints or slight wobble in ring suspension point.
level_4: No teleportation, no distortion, no lighting discontinuity; motion is smooth and physically plausible; suspension point of rings remains stable; figure’s center of mass moves continuously downward then stabilizes; however, one of: very brief frame freeze (≥2 consecutive identical frames), or subtle temporal misalignment between arm extension and torso leveling.
level_5: Zero spatiotemporal artifacts: rings remain rigidly suspended with consistent perspective and parallax; figure’s motion is fluid and continuous across all frames; no frame duplication, no jitter, no lighting fluctuation, no occlusion-induced ambiguity; arm extension, torso leveling, and shoulder alignment occur in coherent, synchronized progression without hesitation or reversal.