Pelvic Floor — Postural Alignment & Assessment Guide

How to check alignment for optimal PF function · hover / tap each card to highlight on the figure

Sagittal view — standing neutral posture

1 Pelvic tilt (neutral check)

The pelvis should be in a neutral position — neither anteriorly tilted (arched low back) nor posteriorly tilted (tucked tailbone). The ASIS and pubic symphysis should be roughly in the same vertical plane.

How: Stand sideways to a mirror. Place one hand on hip bones (ASIS) and one on pubic bone. They should be nearly vertically aligned.

Why: Neutral pelvis maintains the PF dome shape for optimal force distribution. Tucking flattens the dome. position

2 Ribcage-over-pelvis alignment

The lower ribcage should sit directly above the pelvis — not flared forward or collapsed backward. This aligns the diaphragm directly above the PF to form an efficient core piston.

How: Side view — lower ribs should stack over the iliac crests. If ribs flare forward, gently exhale and allow them to drop.

Why: Misaligned piston = pressure leaks sideways instead of transmitting evenly through the PF.

3 Sit-bone awareness (ischial tuberosity width)

When seated, you should feel both sit-bones equally, with a sense of width between them. This means the PF is in a lengthened, domed position rather than gripped.

How: Sit on a firm surface. Rock side to side until you feel both bony points. Gently widen them apart (imagine growing your sit-bones wider).

Why: Widened sit-bones = trampoline springs at optimal tension. Clenched = springs too tight to absorb.

4 Breath pattern (diaphragmatic vs chest)

Proper PF training requires 360° diaphragmatic breathing — ribs expand laterally and belly gently expands, rather than chest-only shallow breathing.

How: Place hands on lower ribs. Inhale — feel ribs push hands outward. Belly should gently expand. Shoulders should NOT rise.

Why: Chest breathing bypasses the core piston entirely. Only diaphragmatic breathing drives PF coordination. inhale_sec exhale_sec

5 Hip rotator engagement (obturator internus)

The deep hip rotators share fascia with the PF. External rotation exercises pre-tension the PF, making the pelvic bowl more stable under load.

How: Standing — gently rotate feet outward without moving knees. You should feel a subtle engagement deep in the hip/pelvis.

Why: Engaging hip rotators shortens the "radius" the PF must support, increasing rigidity of the pelvic ring.

6 Bodyweight

Used as a scaling input for a pelvic load index. This guide uses an adjustable pelvic-contents fraction (default 1.0% of BW; typical range 0.5-1.5%).

How: Bathroom scale, morning, minimal clothing

Why: m_contents = pelvic_contents_fraction × BW bodyweight_kg

Position codes — where you train (gravity on PF)

Code	Position	PF Load Index (illustrative)	Why
1	Supine (lying face up)	~0.3×	Gravity assists — organs press sideways, not down through PF
2	Seated	~0.6×	Partial gravitational load on PF
3	Standing	1.0×	Full gravitational load (baseline reference)
4	Single-leg stance	~1.2×	Full gravity + lateral stability challenge for PF
5	Loaded (holding weight)	~1.4×	Gravity + increased IAP from bracing under load

Progression: start supine (easiest) → build to loaded (hardest). Values are coaching indices, not lab-validated force multipliers.

Activity codes — what spikes IAP demand

Code	Activity	IAP Index (illustrative)	Why
1	Rest / breathing only	1.0×	Baseline — no extra IAP beyond organ weight
2	Cough / sneeze	~2.5-4.0×	Sudden explosive IAP spike — PF must absorb reactively
3	Jump / run	~3.0-4.5×	Repeated high-impact bursts — highest sustained demand
4	Deadlift / heavy lift	~2.0-3.0×	Sustained high IAP with voluntary bracing — controlled but heavy

Position index × Activity index = total PF load index. Example: standing (1.0×) × cough (~3.0×) ≈ ~3.0× resting demand.

Key difference from lever exercises:
There are no bone segment measurements needed. The pelvic floor works as a pressure-management system, not a lever. The inputs are: bodyweight_kg, position (1–5), activity (1–4), and breath tempo (inhale_sec, exhale_sec, hold_top_sec, hold_bot_sec).

The critical training variable is eccentric control time (inhale duration) — slow, controlled inhales where the PF lengthens under IAP load.

PF load model:

PF_load_index = contents_mass × g × position_index × activity_index

where:
  contents_mass = pelvic_contents_fraction × bodyweight_kg
  pelvic_contents_fraction = 0.005-0.015 (default 0.01 for coaching estimates)
  position_index = {supine: ~0.3, seated: ~0.6, standing: 1.0, single-leg: ~1.2, loaded: ~1.4}
  activity_index = {rest: 1.0, cough: ~2.5-4.0, jump/run: ~3.0-4.5, deadlift: ~2.0-3.0}
  g              = 9.81 m/s²

Quality score:
quality = ecc_control_time × position_index × min(1, ecc_con_ratio / 2.0)

Notes: position/activity values are illustrative coaching ranges (not direct instrumented pressure multipliers). IAP ranges vary by task, technique, and individual.