A practitioner's guide to isometric hip adduction and abduction test selection: Maximal force, asymmetry, and muscle...

The purpose of this study was to compare maximal adduction (ADD) and abduction (ABD) force, ADD to ABD ratio (ADD:ABD), inter-limb asymmetries and muscle activity between five isometric hip strength assessment positions. Twenty male athletes performed the following positions: seated (SE), supine at knees with 0° hip flexion (SK_0°) and 45° hip flexion (SK_45°), and supine at ankles bilaterally (SA_BI) and unilaterally (SA_UNI). Normalised muscle activity (%EMG_max) of adductor longus (ADD_LONG), gracilis (GRAC), gluteus medius (G_MED), sartorius (SAR), and lower rectus abdominis (REC_ABD) were also assessed. Significant main effects of assessment position were identified for relative peak force (rPF) and torque (rT), ADD:ABD, ADD asymmetry, and %EMG_max. Significantly greater ADD and ABD rPF and rT were observed in SE and SK_45° compared to SA_BI and SA_UNI. SK_45° elicited the highest ADD_LONG and GRAC %EMG_max during ADD, with SE and SK_45° evoking the highest G_MED %EMG_max during ABD. SK_0° exhibited significantly higher ADD:ABD compared to all positions except SA_UNI. ADD asymmetry was significantly largest in SA_UNI, and REC_ABD %EMG_max was highest in SA_BI during ADD. This data can inform selection of assessment positions based on whether the primary measures of interest are maximal force and muscle activity, or identifying asymmetries.