Squat test performance and execution in children with and without cerebral palsy. (January 2017)

• Record Type: Journal Article
• Authors: Eken, M.M.; Harlaar, J.; Dallmeijer, A.J.; de Waard, E.; van Bennekom, C.A. M; Houdijk, H.
• Is Part Of: Clinical biomechanics. Volume 41(2017)
• Page Start: 98
• Page End: 105
• Publication Date: 2017-01
• Subjects: Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2016.12.006
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Knowledge on lower extremity strength is imperative to informed decision making for children with cerebral palsy (CP) with mobility problems. However, a functional and clinically feasible test is not available. We aimed to determine whether the squat test is suitable for this purpose by investigating test performance and execution in children with cerebral palsy and typically developing (TD) peers. Methods: Squat test performance, defined by the number of two-legged squats until fatigue (max 20), was assessed in twenty children with bilateral CP (6–19 years; gross motor function classification system I–III) and sixteen TD children (7–16 years). Muscle fatigue was assessed from changes in electromyography (EMG). Joint range-of-motion and net torque were calculated for each single squat, to investigate differences between groups and between the 2nd and last squat. Findings: Fifteen children with CP performed < 20 squats (median = 13, IQR = 7–19), while all TD children performed the maximum of 20 squats. Median EMG frequency decreased and amplitude increased in mm. quadriceps of both groups. Ankle and knee range-of-motion were reduced in children with CP during a single squat by 10 to 15°. No differences between 2nd and last squat were observed, except for knee range-of-motion which increased in TD children and decreased in children with CP. Interpretation: Squat test performance was reduced in children with CP, especially in those with more severe CP. Muscle fatigue was present in both children with CP and TD peers, confirming that endurance of the lower extremity was tested. Minor execution differences between groups suggest that standardized execution is important to avoid compensation strategies. It is concluded that the squat test is feasible to test lower extremity strength in children with CP in a clinically meaningful way. Further clinimetric evaluation is needed before clinical implementation. Highlights: Squat test performance was reduced in children with cerebral palsy. Quadriceps fatigued during the test in children with cerebral palsy and typical development Only minor differences in movement execution were present between the groups. Squat test should be considered to identify functional lower extremity strength. Standardized execution is important to minimize compensation strategies.