Slack length of gastrocnemius medialis and Achilles tendon occurs at different ankle angles.

Although muscle-tendon slack length is a crucial parameter used in muscle models, this is one of the most difficult measures to estimate in vivo. The aim of this study was to determine the onset of the rise in tension (i.e.

Characterization of passive elastic properties of the human medial gastrocnemius muscle belly using supersonic shear imaging.

The passive elastic properties of a muscle-tendon complex are usually estimated from the relationship between the joint angle and the passive resistive torque, although the properties of the different structures crossing the joint cannot be easily assessed. This study aimed to determine the passive mechanical properties of the gastrocnemius medialis muscle (GM) using supersonic shear imaging (SSI) that allows the measurement of localized muscle shear modulus (μ). The SSI of the GM was taken for 7 subjects during passive ankle dorsiflexion at a range of knee positions performed on an isokinetic dynamometer.

Neck strength and EMG activity in fighter pilots with episodic neck pain.

Introduction: Neck pain is common in fighter pilots due to repeated exposure to high +Gz loads, but studies comparing neck function in symptomatic and healthy fighter pilots are lacking. This study compared neck strength and EMG activity during maximal isometric contractions in a sitting position in the sagittal and coronal planes in neck pain (SP), asymptomatic fighter pilots (AP), and healthy, male, non-pilot subjects (NPS).

Methods: There were 9 SP, 10 AP, and 8 NPS, all males, who performed maximal isometric neck contractions on a specific dynamometer.

Changes in sEMG parameters among trunk and thigh muscles during a fatiguing bilateral isometric multi-joint task in trained and untrained subjects.

This study aimed to explore changes in the electrical activity distribution among synergist muscles involved in the maintenance of this bilateral multi-joint task. It also tested relations between changes in surface electromyographic (sEMG) parameters with endurance time. Eighteen subjects, trained and untrained in hiking, performed a submaximal (50% of maximal contraction) isometric hiking test until exhaustion.

[Neuromuscular and architectural alterations of the vastus lateralis muscle in elderly patients with unilateral knee osteoarthritis].

Aim: The aim of this study was to determine the mechanisms involved in muscle weakness in elderly patients with unilateral knee osteoarthritis.

Subjects: We investigated 7 patients with unilateral knee osteoarthritis.

Method: We measured knee position sense and isometric maximal voluntary contraction (MVC) of the knee extensors.