A practitioner’s guide to isometric hip adduction and abduction test selection: maximal force, asymmetry, and muscle activity comparisons between assessment positions

Key Points

1. Significant differences exist between testing positions when evaluating hip abduction and adduction isometric strength - specifically maximal force, asymmetries and muscle activity.
2. Practitioners should consider these key differences when selecting testing positions with the goal of ultimately improving the rehabilitation process, specifically exercise prescription and valid longitudinal tracking.

BACKGROUND & OBJECTIVE

Isometric strength assessment is common across high performance sport (1). There are a variety of tools and methods which may be used to assess hip strength. The variability in equipment and testing methods can lead to confusion and false conclusions as values are inaccurately interpreted or compared as part of a single assessment or as part of a longitudinal monitoring process.

The objective of the study was to compare: 1) maximal hip adduction (ADD) and abduction (ABD) strength, 2) inter-limb asymmetry and 3) muscle activity, in five commonly used assessment positions with variable joint-angle combinations and location of force applications.

Isometric strength assessment is common across high performance sport.

Selecting an appropriate testing position to include adductor and abdominal muscle activity is essential.

METHODS

20 healthy male ice hockey players from one team were tested during preseason. All players had at least 10 years of experience in the sport and at least four years of formal strength and conditioning programming.

Testing was completed on a device with a rigid frame and four uniaxial load cells. Participants completed a standardized warm-up prior to testing as well as standardized cueing when performing the tests in the five identified positions. The five positions that assessed isometric abduction and adduction were:

1. Seated with 90 degree hip and knee flexion (forced applied at the knee)

2. Supine with 0 degrees hip and knee flexion (forced applied at the knee)

3. Supine with 45 degrees hip flexion (forced applied at the knee)

4. Supine with 0 degrees hip and knee flexion (bilateral force applied at the ankle)

5. Supine with 0 degrees hip and knee flexion (unilateral force applied at the ankle)

Muscle activity was also recorded via surface EMG during all trials.

RESULTS

As seen in Table 1, significant main effect for assessment position was identified for 1) hip ADD and ABD relative peak force, 2) hip ADD and ABD relative torque, 3) hip ADD:ABD ratio and 4) hip ADD and ADD:ABD symmetry angle. No significant main effect was found for hip ABD symmetry angle.

Significant main effects were found for the adductor longus and rectus abdominis, but not for the gluteus medius, during adduction testing. Additionally, significant main effects were identified for all muscle groups during abduction testing.

LIMITATIONS

This study was completed in a single athlete population (from the same team of male participants) who had extensive sport experience and exposure to formal strength and conditioning programming and therefore, may not be applicable in other populations.

CLINICAL IMPLICATIONS

The objectives of this study were to compare: 1) maximal hip ADD and ABD strength, 2) inter-limb asymmetry and 3) muscle activity, in five commonly used assessment positions with variable joint-angle combinations and location of force applications.

1) Maximal hip ADD and ABD strength The seated position and supine at knees with hip at 45 degrees of flexion positions elicited the greatest ADD and ABD relative peak force and relative torque, with moderate to large significant differences compared to testing in the supine position at the ankles bilaterally and unilaterally. Relative torque for hip ABD, but not hip ADD, was significantly lower in the supine position at knees compared to the seated and supine position at hip at 45 degrees of flexion.

2) Inter-limb asymmetry Inter-limb asymmetries for hip ADD and hip ABD: ABD were significantly greater in the supine position at ankles tested unilaterally compared to all other positions.

3) Muscle activity Maximal muscle activity differed significantly across assessment positions. The supine position at knees at 45 degrees of flexion elicited the highest maximum EMG percentage for the adductor longus and gracilis during ADD testing and for the sartorius during ABD testing.

However, it is important to acknowledge individuals testing in the supine position at knees at 45 degrees of flexion may be able to utilize a medial hip rotation moment to generate more force. The gluteus medius displayed the highest maximum EMG percentage in the seated and supine position at knees at 45 degrees of flexion during ABD testing.

The majority of adductor injuries are diagnosed as injury to the adductor longus (2), which shares a common aponeurosis with the abdominal muscles. Selecting an appropriate testing position to include adductor and abdominal muscle activity is essential.

In terms of normalized muscle activity between testing positions for hip ADD and hip ABD, significant main effects were found for the adductor longus in the testing position of supine at ankles with hips at 0 degrees appears to be the most relevant assessment position to monitor rehabilitation progress following an adductor or core muscle injury since it elicits the greatest co-activation of the abdominal and adductor muscles.

+STUDY REFERENCE

Secomb J (2024) A practitioner's guide to isometric hip adduction and abduction test selection: Maximal force, asymmetry, and muscle activity comparisons between assessment positions. Journal of sports sciences, 42(24), 2368–2375.

SUPPORTING REFERENCE

1. Herrington, L. C., Munro, A. G., & Jones, P. A. (2018). Assessment of factors associated with injury risk. In P. Comfort, P. A. Jones, & J. J. McMahon (Eds.), Performance assessment in strength and conditioning (pp. 53–95). Routledge.
2. Serner, A., Tol, J. L., Jomaah, N., Weir, A., Whiteley, R., Thorborg, K., Robinson, M., & Hölmich, P. (2015). Diagnosis of Acute Groin Injuries: A Prospective Study of 110 Athletes. The American journal of sports medicine, 43(8), 1857–1864.