Extension
Extension is a joint movement that generally increases the angle between articulating body segments. Its direction and normal range depend on the joint; movement beyond the usual extension range is called hyperextension.
Definition
Extension is commonly described in the sagittal plane and contrasts with flexion. Examples include straightening the elbow or knee, moving the thigh posteriorly at the hip and returning an extended trunk toward anatomical position. The ankle uses the more specific terms plantar flexion and dorsiflexion, so “triple extension” is coaching shorthand rather than three identical joint actions. Hyperextension can be a normal individual feature or a movement beyond a joint’s usual anatomical position; loaded movement alone does not establish injury.
OpenStax Anatomy & Physiology · body movements
HYROX® examples
HYROX® includes running, Wall Balls, Sandbag Lunges, Sled Push, Sled Pull, Burpee Broad Jumps, SkiErg and Row. Hip and knee extensors contribute during parts of these tasks, while shoulder extension can occur during pulling. The exact joint sequence and range vary with technique, speed, load and athlete. The rulebook does not rank stations by extension demand or require maximal hip extension at every step, stroke or repetition.
HYROX® Singles Rulebook 2026/27 · OpenStax Anatomy & Physiology · body movements
Running and range claims
Running includes alternating hip motion, but the claim that limited hip extension necessarily shortens stride and worsens running economy is too strong. A 2024 meta-analysis found no significant association between hip angles or range of motion and economy, and stride length also showed a trivial non-significant association. Earlier work supports staying near a self-selected stride rather than forcing more extension. A “tall hips” cue may change one runner’s technique but cannot guarantee better economy.
Van Hooren et al. · running biomechanics/economy meta-analysis · Moore · running-economy biomechanics review
Training application
Deadlifts, hip thrusts, squats, leg presses and rows can train muscles involved in different extension actions. Exercise choice, range and load should match the intended joint action, task and athlete. “Full extension” is not one universal endpoint across exercises, and deliberately forcing range beyond control is unnecessary. Station practice can develop task skill, but slow Sled Push time does not diagnose hip-extension weakness.
ACSM · resistance-training prescription position stand · HYROX® Singles Rulebook 2026/27
Frequently Asked Questions
Which HYROX® station requires the most extension?
No comparative evidence reviewed here ranks the stations this way. Sled Push and Wall Balls use hip and knee extension, while other tasks use different extension actions and whole-body coordination.
HYROX® Singles Rulebook 2026/27
What causes limited hip extension?
Possible contributors include joint structure, symptoms, muscle or tendon capacity, motor strategy and measurement position. Prolonged sitting or “short hip flexors” cannot be assumed to be the cause from range alone; assessment should guide any mobility work.
OpenStax Anatomy & Physiology · body movements · Van Hooren et al. · running biomechanics/economy meta-analysis
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Repz performance data can reveal if your sled push times are lagging, which may indicate hip extension weakness.
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