Individuals With Chronic Ankle Instability Show Abnormalities in Maximal and Submaximal Isometric Strength of the Knee Extensor and Flexor Muscles.

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).

Towards a comprehensive biomechanical assessment of the elderly combining in vivo data and in silico methods.

The aging process is commonly accompanied by a general or specific loss of muscle mass, force and/or function that inevitably impact on a person's quality of life. To date, various clinical tests and assessments are routinely performed to evaluate the biomechanical status of an individual, to support and inform the clinical management and decision-making process (e.g., to design a tailored rehabilitation program). However, these assessments (e.g., gait analysis or strength measures on a dynamometer) are typically conducted independently from one another or at different time points, providing clinicians with valuable yet fragmented information. We hereby describe a comprehensive protocol that combines both in vivo measurements (maximal voluntary isometric contraction test, superimposed neuromuscular electrical stimulation, electromyography, gait analysis, magnetic resonance imaging, and clinical measures) and in silico methods (musculoskeletal modeling and simulations) to enable the full characterization of an individual from the biomechanical standpoint. The protocol, which requires approximately 4 h and 30 min to be completed in all its parts, was tested on twenty healthy young participants and five elderlies, as a proof of concept. The implemented data processing and elaboration procedures allowing for the extraction of several biomechanical parameters (including muscle volumes and cross-sectional areas, muscle activation and co-contraction levels) are thoroughly described to enable replication. The main parameters extracted are reported as mean and standard deviation across the two populations, to highlight the potential of the proposed approach and show some preliminary findings (which were in agreement with previous literature).

Effects of MLS Laser on pain, function, and disability in chronic non-specific low back pain: A double-blind placebo randomized-controlled trial.

BACKGROUND: Among non-pharmacological interventions, Multiwave Locked System (MLS) Laser therapy has been used in patients with several musculoskeletal pathologies and in combination with other therapeutical interventions. The effects of sole MLS therapy on pain and function in patients with chronic non-specific low-back pain are unknown. OBJECTIVE: The objective of this study was to investigate the effects of MLS Laser therapy on pain, function, and disability in patients with chronic non-specific low back pain in comparison to a placebo treatment group. METHODS: Forty-five patients were randomized into two groups: the MLS Laser group and the Sham Laser group, undergoing 8 sessions of either a MLS Laser therapy or a Sham Laser therapy, respectively. At the beginning of the therapy (T0), at the end of the therapy (T1), and 1 month after the end of therapy (T2) patients were assessed for low back pain (by means of a VAS scale), function (by means of kinematic and electromyographic assessment of a forward bending movement) and self-reported disability (by means of the Roland-Morris and Oswestry Disability questionnaires). RESULTS: There was a significant reduction of pain and disability in both groups at T1 and T2 in comparison with T0. At T2 patients in the MLS group showed a significantly lower pain in comparison with patients in the Sham group (VAS = 2.2 ± 2 vs. 3.6 ± 2.4; p< 0.05). No differences between the two groups were found for function and disability. CONCLUSION: Both MLS Laser and Sham Laser therapies lead to a significant and comparable reduction in pain and disability in patients with chronic non-specific low back pain. However, one month after treatment, MLS Laser therapy has been found to be significantly more effective in reducing pain as compared to sham treatment.