Gluteus medius muscle activity during gait in people with and without chronic nonspecific low back pain: A case control study.

Background: Research investigating differences in gluteus medius muscle activity in those with and without chronic nonspecific low back pain is both limited and conflicting. Additionally, in these populations the relationship between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness is unclear.

Research Question: We aimed to investigate gluteus medius muscle activity during gait in those with and without chronic nonspecific low back pain. Secondarily, we aimed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness within groups.

Methods: This case control study recruited 30 people with and 30 people without chronic nonspecific low back pain and matched participants by age (±5 years), sex, and body mass index (±2 BMI units). Gluteus medius muscle activity was measured with surface electromyography during walking gait, with foot type and transversus abdominis muscle thickness measured with the Foot Posture Index and ultrasound respectively. The Mann-Whitney U test was used to investigate differences in gluteus medius muscle activity between groups. Spearman rank order correlation was performed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis thickness within each group. A linear regression was used to analyse significant correlations (P < 0.05).

Results: We found no significant differences in gluteus medius muscle activity between groups. However, there was a moderate correlation between the Foot Posture Index score and gluteus medius peak amplitude (P = 0.04) for those with mild to moderate chronic nonspecific low back pain.

Significance: Clinicians should be aware that patients with mild to moderate chronic nonspecific low back pain may not demonstrate significant differences in gluteus medius muscle activity compared to those without back pain. Additionally, higher peak gluteus medius muscle activity is likely to occur in people with mild to moderate chronic nonspecific low back pain and planus feet.