BioFlex Pro Muscle strength and flexibility are essential for maintaining the neutral spine position. Weak abdominal muscles tend to tighten the hip flexor muscles, causing an increase in the curvature of the lower back. An unhealthy posture results when the curve BioFlex Pro is overweight, called lordosis or Swayback. Proper posture corrects muscle inequalities that can lead to back pain by distributing the weight evenly across the spine. http://www.bluesupplement.com/bioflex-pro/