Direct answer
Nitric oxide relaxes penile smooth muscle so blood can enter. Men support NO with sleep, aerobic fitness, nitrate-rich vegetables, and — when fundamentals are set — citrulline or pycnogenol stacks discussed with a clinician.
Why does this matter for men?
NO is the chemical hinge — lifestyle is the dial.
What causes this?
- Low vegetable intake
- Smoking
- Poor endothelial health from visceral fat
What should you do next?
- Daily nitrate serving (greens, beetroot).
- Zone-2 cardio 2× weekly.
- See blood flow guide for full sequence.
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The Control Protocol is coaching and education — not medical care. Sudden erectile loss, pain, or medication concerns belong with a licensed clinician first.