Effect of surface inclination and gluteus maximus activation on lumbar lordosis and footpronation in individuals with low back pain with extension pattern: a preliminary study

Lumbar hyperlordosis and foot overpronation are associated with low back pain with extension pattern. This study examined if standing and walking on inclined surface or gluteus maximus activation alleviates the extent of lumbar lordosis and foot pronation amongst individuals with LBP who were classified with extension pattern. Eighteen adults with foot overpronation (LBP group, n = 9 and non-LBP group, n = 9) participated in this cross-sectional and case-control comparison study. Lumbar lordotic angle and rearfoot angle were measured using surface tomography, during standing and walking on treadmill at inclinations of 0°, 6° and 9°, and voluntary gluteus maximus activation at 20%, 40% and 60% of maximal contraction in standing at 0° inclination. The lumbar lordosis angle and rearfoot angle were compared within-group and between two groups across the listed trials in standing and walking. Results indicated no significant change in lumbar lordosis or rearfoot angle in LBP group when standing or walking on 6°or 9°inclined surface (p > 0.05). However, voluntary gluteus maximus activation in standing at the level of 20%, 40% and 60% of maximal effort reduced lumbar lordotic angle (p < 0.05) but not rearfoot angle (p > 0.05) in LBP group. Our findings provide a novel approach to address the hyperlordosis in LBP group with extension pattern, for which voluntary gluteus maximus activation of ≥ 20% of maximal effort could effectively reduce the extent of the lumbar lordosis in level-ground standing in the LBP group. Such modified lumbar posture may alleviate the compressive loading on the spine associated with static upright standing at our daily activities. Increased gluteus maximus activation found during inclined walking may be beneficial to those with LBP and extension pattern.