The Effect of Lumbar Multifidus and Transversus Abdominis Muscle Activation on Balance in Patients With Hemiplegia

Trunk muscle dysfunction in stroke patients leads to both balance impairments and excessive compensatory effort to maintain postural control. While some patients completely lose their ambulation ability due to stroke, others experience increased postural sway and impaired balance, which elevate the fear and risk of falling. Previous studies have demonstrated a significant relationship between static balance, duration of hospital stay, and post-stroke functional abilities. Furthermore, early-stage trunk muscle control has been shown to be a strong predictor of activities of daily living within the first six months post-stroke. Although numerous studies have proven the efficacy of core stabilization exercises on balance and functional outcomes in hemiplegic patients, data on individual deep muscle dynamics remain limited.

Therefore, this cross-sectional study aimed to investigate the relationship between ultrasound-measured bilateral transversus abdominis and bilateral lumbar multifidus muscle values and balance performance in patients with hemiplegia. The study population consists of adult patients diagnosed with post-stroke hemiplegia who underwent clinical and ultrasonographic evaluations. Participants are selected from patients receiving inpatient or outpatient rehabilitation at a single tertiary training and research hospital, according to specific functional and clinical eligibility criteria using a non-probability convenience sampling method.

To standardize the ultrasonographic measurements and minimize inter-individual variations, specific muscle parameters are calculated and integrated into the statistical analyses:

Paretic Thickening Fraction (TF) = ([Contraction Thickness - Resting Thickness] / Resting Thickness) x 100,

Resting Thickness Ratio (RTR) = (Paretic Resting Thickness / Non-paretic Resting Thickness) x 100,