Body systems map

Grip and forearms

What it does on course

Holds bars, ropes, and carries. Fails first when muddy or cold.

Standards

• Beginner: Dead hang 30-45 s. Towel hang 15-20 s.
• Advanced: Dead hang 60-90 s. Towel hang 30-45 s. Farmer ~50-65% BW × 60-90 s.
• Expert: Dead hang 90-120+ s. Towel hang 45-60+ s. Farmer ~65-75% BW × 90 s+.

Drills

Dead hangs with active scapular set. Farmer carries. Towel hangs / plate pinches.

Mobility

Forearm extensors soft enough for pain-free wrist extension in crawl stance.

Obstacles that punish weakness

Monkey bars Trapeze rings Inverted ladder High walls Halfpipe Floating blocks

Shoulders and lats

What it does on course

Pulls you onto walls, stabilizes hangs, powers swim-like strokes in water.

Standards

• Beginner: Pull-ups ~3-5 (M) / 1-3 or flexed-arm hang 20-30 s (W). Active hang 20-30+ s.
• Advanced: Pull-ups ~8-12 (M) / 4-8 (W). Active hang 30+ s with scapular depression.
• Expert: Pull-ups 12-15+ (M) / 8-12+ (W) with sets after running.

Drills

Pull-ups / rows. Scapular pull-ups. Band external rotations.

Mobility

Overhead reach with ribs down. Thoracic extension for wall slides.

Obstacles that punish weakness

High walls Halfpipe Human pyramid Quarterpipe Pipe climb Cargo A-frame Floating blocks

Trunk and core

What it does on course

Links limbs for crawls, carries, and wall launches. Protects the low back under fatigue.

Standards

• Beginner: Front plank 60 s. Side plank 30-45 s each.
• Advanced: Front plank 90-120 s. Side plank 60-90 s each.
• Expert: Front plank 120+ s with hollow quality. Side plank 90+ s, symmetric.

Drills

Dead bug / hollow hold. Side plank + suitcase carry. Bear crawl / lizard crawl.

Mobility

Segmental thoracic rotation without lumbar twist dump.

Obstacles that punish weakness

Mud crawl Cargo-net crawl Underwater cage Mud trenches Human pyramid Floating blocks

Hips and glutes

What it does on course

Hinge for lifts, power for walls and Quarterpipe, stabilize lateral mud steps.

Standards

• Beginner: Clean bodyweight hip hinge. 20+ controlled walking lunges/leg. Single-leg bridge 30 s/side.
• Advanced: Same patterns under mild fatigue. Sandbag bear-hug carries for time.
• Expert: Explosive step-ups and hill power with soft landings after.

Drills

Hip thrusts / glute bridges. Step-ups. Lateral band walks. Sandbag bear-hug carries.

Mobility

Half-kneeling hip flexor length without lumbar arch.

Obstacles that punish weakness

Mud trenches Quarterpipe Human pyramid Cargo A-frame Log hold Floating blocks

Quads

What it does on course

Step-ups, climbs, muddy runs, landing absorption.

Standards

• Beginner: 20-30 reverse lunges/leg. Step-up to ~knee height × 10+/leg unbroken.
• Advanced: Same under light fatigue after easy running.
• Expert: Hill repeats with controlled descents (cut volume in taper).

Drills

Split squats. Step-ups. Short hill repeats.

Mobility

Kneeling quad stretch. Ankle dorsiflexion so knees track without collapse.

Obstacles that punish weakness

Log hold Mud trenches Inverted ladder Quarterpipe

Hamstrings

What it does on course

Deceleration on descents, hip hinge for picks, short sprint segments.

Standards

• Beginner: Controlled single-leg RDL pattern without pain.
• Advanced: Nordic progression or bridge-curl comfort without pain.
• Expert: Tempo step-downs under fatigue with quiet landings.

Drills

RDLs. Hamstring slides. Tempo step-downs.

Mobility

Straight-leg raise / hinge mobility without rounding compensation.

Obstacles that punish weakness

Hidden pits Quarterpipe Mud trenches

Calves and ankles

What it does on course

Traction on uneven mud, push-off, landing stiffness.

Standards

• Beginner: Knee-to-wall (heel down) ≥10 cm. Single-leg calf raise 20-25/side.
• Advanced: ≥12 cm preferred. Side-to-side gap under ~2 cm.
• Expert: Symmetric ≥12 cm with invert/evert control barefoot on a towel.

Drills

Calf raises. Ankle CARs. Easy short hill bounces in taper.

Mobility

Weight-bearing lunge ≥10 cm. Invert/evert control barefoot on a towel.

Obstacles that punish weakness

Hidden pits Cargo A-frame Shock gauntlet

Feet and footwear

What it does on course

Only contact patch with mud. Blister and black-toe risk.

Standards

• Beginner: Complete a wet muddy run in race shoes and socks with no hot spots.
• Advanced: Shoes drain and stay on through a longer muddy trail.
• Expert: Full kit wet dress rehearsal with zero blister surprises.

Drills

Trail runs in race kit. Short barefoot intrinsic foot work off-course.

Mobility

Big-toe extension for push-off. Comfortable toe-splay in shoe.

Obstacles that punish weakness

Cargo A-frame Log hold Mud trenches Shock gauntlet

Lungs and breathing

What it does on course

Oxygen between obstacles, cold-shock control, Underwater cage air-gap management.

Standards

• Beginner: Conversational pace on easy miles. Nasal-breathe easy jogs.
• Advanced: Cold shower exhale control with airway free (standing).
• Expert: Calm narrative through a visualized ice dunk without panic spirals.

Drills

Easy aerobic runs. Nasal breathing on easy work. Cold shower exhale control (airway free).

Mobility

360° rib expansion. Relaxed upper traps at rest.

Obstacles that punish weakness

Ice plunge Underwater cage Pipe climb Irritant tunnel Floating blocks

Mind and nervous system

What it does on course

Interprets the cold gasp as survivable, chooses help, paces ego.

Standards

• Beginner: Narrate a cold-entry plan calmly.
• Advanced: Complete a dress-rehearsal session without catastrophic thinking spirals.
• Expert: Downshift from panic in under 60 s on land with exhale-focused breathing.

Drills

Visualization of Ice plunge / Underwater cage / heights. Box breathing away from water. Practice asking for and giving wall help.

Mobility

Exhale-led calm before fear obstacles.

Obstacles that punish weakness

Ice plunge Underwater cage Inverted ladder Cargo A-frame Irritant tunnel Live-wire crawl Shock gauntlet Floating blocks