Impact of Abdominal Muscle-Induced Fatigue on Hip Muscle Performance and Functional Balance in Healthy Adults

The study is based on the theory that the abdominal muscles contribute to transverse and frontal plane torques that complement hip abductor torque, as both muscle groups act in the same counterclockwise direction within the proposed biomechanical model. Through their role in trunk and pelvic stabilization, the abdominal muscles help optimize the mechanical environment in which the hip abductors operate, potentially enhancing their effective torque production during functional tasks.

This shared torque direction suggests a functional interdependence between core and hip musculature, whereby deficits or fatigue in the abdominal muscles may compromise hip abductor performance and load distribution at the hip joint. Clinically, this relationship supports the integration of abdominal muscle assessment and targeted core rehabilitation into the evaluation and management of hip-related injuries, with the potential to improve movement control, reduce injury risk, and enhance treatment outcomes. A quasi-experimental, within-subject study conducted at the Isokinetic Laboratory, Faculty of Physical Therapy, Cairo University, to examine the effect of abdominal muscle-induced fatigue on hip muscle strength, endurance, and functional balance. Seventy healthy male college students aged 20-25 years will be assessed before and after an isokinetic abdominal fatigue protocol using an isokinetic dynamometer. Outcome measures include isokinetic hip muscle strength and endurance, as well as balance assessed by the Single Leg Stance Test and Star Excursion Balance Test. The study procedure consists of participant preparation, baseline assessment, abdominal muscle fatigue induction, and immediate post-fatigue reassessment. Sample size was determined using G*Power to ensure adequate statistical power, and data will be analyzed using one-way within-subject MANOVA with significance set at p < 0.05. This study holds critical importance for advancing both biomechanical theory and clinical practice by directly investigating a key, yet under-quantified, link in the human kinetic chain: the specific impact of abdominal muscle fatigue on hip muscle performance and functional balance. By employing instrumented (Isokinetic dynamometer, star excursion balance test and single leg stance test)., pre- and post-fatigue measurements in a healthy non-athletic population, it will generate novel empirical evidence clarifying how core endurance directly influences proximal stability and distal function. Clinically, the outcomes promise to transform assessment and rehabilitation paradigms-shifting focus from isolated hip treatment toward integrated core-hip strategies-ultimately informing more effective injury prevention programs, optimizing movement efficiency, and enhancing rehabilitation outcomes for both athletic and general populations.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Adult Participants
• Intervention / Treatment: Other: Isokinetic Dynamometer for fatiguing abdominal muscles and assessing hip Muscle Performance, and balance assessment using star excursion test and single leg balance test

• Study Type: Observational
• Enrollment (Estimated): 70

Contacts and Locations

• Study Contact: Name: Ahmed Samir Abdel Latif, MSc in Biomechanics; Phone Number: 01222832888; Email: ahmedsamir9430@gmail.com

Study Locations

• Egypt
  • Giza Governorate
    • Giza, Giza Governorate, Egypt, 12534
      • Degla Palms
      • Contact: Ahmed Samir Abdel Latif, MSc in Biomechanics; Phone Number: 01222832888; Email: ahmedsamir9430@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of 70 healthy, non-athletic students aged between 20 and 25 years. These participants were specifically selected to maintain homogeneity in the data, ensuring they possess the necessary physical capacity to perform the required isokinetic contractions and manual muscle tests while remaining free from recent injury, musculoskeletal pain, or neurological conditions that could compromise the accuracy of the balance and strength assessments.

Description

Inclusion Criteria:

• Healthy colleague male students aged 20-25 years (Cerda et al., 2018).
• No history of low back, hip, knee or pelvic surgery in past year (Hietamo et al., 2021).
• Physically able to perform isokinetic contractions against isokinetic dynamometer (Babiloni et al., 2025).
• Body mass index (BMI) from 18 to 25 (Milanese et al., 2025).
• Abdominal and Hip manual muscle test of 4 or above (Ciesla et al.,2011).

Exclusion Criteria:

• Current musculoskeletal pain in trunk, hip, or lower limb (Hietamo et al., 2021).
• Neurological disorders affecting balance (e.g vertebra basilar insufficiency) or muscle performance (Pongmala et al., 2024).
• Recent participation (48-72 h) in strenuous trunk/hip exercise that might confound fatigue measures (Foucher et al., 2021).
• Participation in athletic activities (Elliott et al., 2021).

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Study Group; Seventy healthy colleague students aged from 20 to 25 will participate in this study, they will all be placed in one group that will be tested before and after the abdominal muscle fatigue protocol for their hip muscle strength, endurance using Isokinetic dynamometer and functional balance using star excursion test and single leg balance test

Other: Isokinetic Dynamometer for fatiguing abdominal muscles and assessing hip Muscle Performance, and balance assessment using star excursion test and single leg balance test; To assess physical performance, this study utilizes three specialized tools to measure strength, endurance, and balance. The isokinetic dynamometer serves as the clinical "gold standard" for quantifying muscle performance, providing highly standardized and sensitive data to induce abdominal muscle fatigue and evaluate the strength and endurance of the hip musculature. For balance assessment, the study uses the Star Excursion Balance Test (SEBT) to measure dynamic postural control; by recording the maximum distance a participant can reach while standing on one leg, it identifies sensorimotor deficits and provides a reliable index of stability. Complementing this is the Single Leg Stance (SLS) test, a validated, straightforward method for evaluating static balance by measuring the duration a participant can maintain a barefoot, one-legged position. Together, these tools provide a comprehensive evaluation of both strength-based fatigue and multi-directional stability.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hip Abductors Muscle Strength	Assess hip Abductor muscle strength using Isokinetic Dynamometer after fatiguing the abdominal muscles Unite: N.m	One week
Hip Extensor Muscle Strength	Assess hip Extensor muscle strength using Isokinetic Dynamometer after fatiguing the abdominal muscles Unite: N.m	One week
Hip Flexor Muscle Strength	Assess hip Abductor muscle strength using Isokinetic Dynamometer after fatiguing the abdominal muscles Unite: N.m	One Week
Hip Adductor Muscle Strength	Assess hip Abductor muscle strength using Isokinetic Dynamometer after fatiguing the abdominal muscles Unite: N.m	One Week

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hip Abductor Endurance Test	Assess hip Abductor muscle endurance using Isokinetic Dynamometer after fatiguing the abdominal muscles Measured by Fatigue Index	One Week
Hip Extensor Endurance Testing	Assess hip Extensor muscle endurance using Isokinetic Dynamometer after fatiguing the abdominal muscles Measured by Fatigue Index	One Week
Hip Flexor Endurance Testing	Assess hip Flexor muscle endurance using Isokinetic Dynamometer after fatiguing the abdominal muscles Measured by Fatigue Index	One Week
Hip Adductor Endurance Testing	Assess hip Adductor muscle endurance using Isokinetic Dynamometer after fatiguing the abdominal muscles Measured by Fatigue Index	One Week
Balance Testing Using Star Excursion test	Balance testing after abdominal muscle fatigue using star excursion test Unite: Seconds	One week
Balance Testing Using Single Leg Stance Test	Balance testing after abdominal muscle fatigue using Single Leg Stance Test Unite: Seconds	One Week

Collaborators and Investigators

• Sponsor: Cairo University

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): January 30, 2027

Study Registration Dates

• First Submitted: April 26, 2026
• First Submitted That Met QC Criteria: May 5, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 5, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: P.T.REC/012/006299

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No