Sled Push · Trunk Angle at Contact

Why this matters

This is the same measurement as the brace trunk angle, taken one phase later — at the moment the front foot plants. Measuring it twice is deliberate: the comparison exposes the most common fatigue fault on the sled push.

Does the chest stay low as the athlete steps, or does it pop up?

Each time the chest rises between steps, the force vector tilts upward and the sled loses horizontal drive. Over 50 m of repeated steps, a chest that creeps up costs real time.

What good looks like

• Trunk angle at contact matches the brace angle (within a few degrees).
• The torso holds its low, long line through the whole step cycle.
• No visible "bobbing" of the chest between steps.

Common faults

Chest Pop-Up (> 22°)

The chest rises as the athlete steps. The classic fatigue tell — the position degrades step by step. Every rise bleeds horizontal force, so the sled decelerates between drives.

Causes: fatigue, weak isometric trunk endurance, or rushing the cadence.

Effect: force leaks upward, sled stutters, split slows.

Too Flat (< 8°)

Dropped further at contact than at the brace — over-committed and hard to repeat under fatigue.

Coaching cues

• "Stay long as you step" — keeps the torso pinned to its brace angle.
• "Don't let the chest breathe" — names the pop-up directly.
• Side-by-side film — show the brace frame and the contact frame together; the rise is obvious once seen.

How to draw

1. Pause on the same front-foot-plant frame as the Shin Angle.
2. First point: greater trochanter (hip).
3. Second point: acromion (shoulder).
4. The acute angle vs horizontal is the reading. Compare it to the brace value.

Related measurements

• Trunk Angle at Brace — the reference reading this is compared against.
• Shin Angle at Contact — same frame; the lower-body half of the plant.