Labanca L, Tedeschi R, Mosca M, Benedetti MG. Individuals With Chronic Ankle Instability Show Abnormalities in Maximal and Submaximal Isometric Strength of the Knee Extensor and Flexor Muscles.
Am J Sports Med 2024;
52:1328-1335. [PMID:
38459686 PMCID:
PMC10986150 DOI:
10.1177/03635465241232090]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/15/2023] [Indexed: 03/10/2024]
Abstract
BACKGROUND
It has been shown that chronic ankle instability (CAI) leads to abnormalities in neuromuscular control of more proximal joints than the ankle. Although strength of the hip and the ankle muscles has been largely investigated providing concordant results, limited evidence with contrasting results has been reported regarding knee extensor and flexor muscles.
PURPOSE
To investigate maximal and submaximal isometric muscle strength in individuals with CAI.
STUDY DESIGN
Controlled laboratory study.
METHODS
Fifteen participants with unilateral CAI and 15 healthy matched controls were recruited. To quantify maximal strength, peak forces were recorded during a maximal isometric voluntary contraction of knee extensor and flexor muscles at 30° and 90° of knee flexion and normalized by the body weight of each participant. At both angles, submaximal isometric contractions at 20%, 50%, and 80% of the maximal voluntary isometric contraction were performed to analyze strength steadiness, in terms of coefficient of variation, and strength accuracy, in terms of absolute error. During all the assessments, knee extensor and flexor muscle activation was recorded by means of surface electromyography.
RESULTS
Knee flexor maximal isometric strength was significantly lower in the injured limb of individuals with CAI in comparison with healthy controls at both 30° (0.15 ± 0.05 vs 0.20 ± 0.05; P < .05) and 90° (0.14 ± 0.04 vs 0.18 ± 0.05; P < .05). Knee extensor and flexor steadiness was significantly lower (higher coefficient of variation) in both the injured and the noninjured limbs of individuals with CAI in comparison with healthy individuals at 90° and at 30° for knee flexor steadiness of the injured limb. Knee extensor and flexor accuracy was lower (higher absolute error) in both the injured and noninjured limbs of individuals with CAI in comparison with healthy individuals, mainly at 30°, while at 90° it was lower only in the injured limb. No differences between the 2 groups were found for maximal isometric strength of knee extensor muscles, as well as for muscle activations.
CONCLUSION
Individuals with CAI show abnormalities in maximal and submaximal isometric strength of knee flexor muscles, and submaximal strength of the knee extensor muscles. Further studies should deeply investigate mechanisms leading to these abnormalities.
CLINICAL RELEVANCE
Rehabilitation interventions should consider abnormalities of neuromuscular control affecting joints more proximal than the ankle in individuals with CAI.
REGISTRATION
NCT05273177 (ClinicalTrials.gov identifier).
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