Effectiveness of a Six-Week Progressive Resistance Exercise Program on Lumbopelvic Range of Motion in Second-Trimester Pregnancy: A Randomized Controlled Trial

Low back pain and pelvic girdle pain constitute the most prevalent musculoskeletal complaints during pregnancy, collectively affecting 50% to 70% of pregnant women, with prevalence escalating substantially during second and third trimesters. These conditions exhibit multifactorial etiology involving altered biomechanics, compromised neuromuscular control, weakened core musculature, and progressive joint stiffness. The syndrome extends beyond subjective pain to encompass objective functional impairments including restricted lumbopelvic range of motion, compromised postural stability, reduced occupational capacity, increased sick leave utilization, and elevated fall risk, collectively imposing substantial individual and societal burdens. Biomechanical alterations include increased spinal loading (estimated at 56% elevation above non-pregnant baseline), hormonal mediation of ligamentous integrity affecting sacroiliac and pubic symphysis articulations, and neuromuscular control deficits impairing load transfer mechanisms across the lumbopelvic complex.

Therapeutic exercise has emerged as a cornerstone non-pharmacological intervention in prenatal care. Structured protocols targeting core stability, spinal mobility, and pelvic floor function demonstrate beneficial effects on pain reduction, postural optimization, and functional capacity preservation. A 2019 systematic reviews established that prenatal exercise reduces pain severity and improves functional capacity, though effects on symptom prevalence remain equivocal. Exercise enhances lumbopelvic stability through strengthening deep abdominal and paraspinal musculature, improving neuromuscular coordination and proprioceptive acuity, optimizing load distribution across compromised joints, and potentially modulating inflammatory cascades contributing to pain sensitization. Randomized controlled trials (RCT) indicated that combined stabilization and pelvic floor training surpasses isolated exercise approaches for improving lumbopelvic function and reducing disability.

The present investigation addressed these methodological limitations through a RCT design incorporating validated goniometric assessment of eight discrete lumbopelvic range of motion parameters across three temporal measurement points. The study compared outcomes between pregnant women participating in a structured six-week progressive resistance exercise program targeting lumbopelvic stabilizers and controls engaging only in routine daily activities. This design enables characterization of both intervention effects (comparing exercising (experimental group) vs. non-exercising group (control group) and natural gestational trajectories (examining temporal changes within the control group), thereby providing comprehensive evidence regarding therapeutic exercise efficacy and the biomechanical consequences of pregnancy progression in the absence of structured physical conditioning. The primary aim was to evaluate whether a structured therapeutic exercise rehabilitation protocol could counteract gestational mobility decline and enhance lumbopelvic range of motion in second-trimester pregnant women through targeted neuromuscular conditioning. The investigators hypothesized that the progressive resistance exercise intervention would generate substantial improvements in all measured lumbopelvic mobility parameters, while control participants would exhibit progressive restrictions as pregnancy advanced, resulting in large between-group differences favoring the intervention group at postintervention assessment. The secondary aim was to compare back and pelvic pain between the two groups.