Influence of Stretch Speed and Arousal State on Passive Ankle Joint Mechanics.

Studies investigating the mechanisms influencing maximum passive joint range of motion (ROM) and stiffness have not objectively assessed the possible influence of stretch speed and/or arousal state. The purpose of this study was to assess the effects of arousal state and stretch speed on healthy individuals ROM, stiffness, gastrocnemius medialis, and soleus electromyographic activity (EMG). Fourteen participants performed one familiarization and then one testing session on separate days in the laboratory.

Motoneuron persistent inward current contribution to increased torque responses to wide-pulse high-frequency neuromuscular electrical stimulation.

Purpose: To assess the effect of a remote handgrip contraction during wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) on the magnitude of extra torque, progressive increase in torque during stimulation, and estimates of the persistent inward current (PIC) contribution to motoneuron firing in the plantar flexors.

Methods: Ten participants performed triangular shaped contractions to 20% of maximal plantar flexion torque before and after WPHF NMES with and without a handgrip contraction, and control conditions. Extra torque, the relative difference between the initial and final torque during stimulation, and sustained electromyographic (EMG) activity were assessed.

Do Intramuscular Temperature and Fascicle Angle Affect Ultrasound Echo Intensity Values?

Purpose: Ultrasound-derived echo intensity (EI) has been used as a physiological marker for changes in skeletal muscle "quality" with physical training, disuse, aging, and neuromuscular disorders. However, the methodological and physiological factors influencing EI and its longitudinal change are still unclear. Here, we performed two separate experiments to investigate the effects of muscle temperature and fascicle angle, which are known to influence muscle tissue and sound wave properties and therefore affect EI.

Isokinetic eccentric exercise substantially improves mobility, muscle strength and size, but not postural sway metrics in older adults, with limited regression observed following a detraining period.

Introduction: Eccentric exercise can reverse age-related decreases in muscle strength and mass; however, no data exist describing its effects on postural sway. As the ankle may be more important for postural sway than hip and knee joints, and with older adults prone to periods of inactivity, the effects of two 6-week seated isokinetic eccentric exercise programmes, and an 8-week detraining period, were examined in 27 older adults (67.1 ± 6.

Comparing Maximal Mean and Critical Speed and Metabolic Powers in Elite and Sub-elite Soccer.

The quantification of maximal mean speed (MMS), maximal mean metabolic power (MMP), critical speed (CS) and critical metabolic power (CP) was conducted over full A-League (elite) and National Premier League (NPL; sub-elite) seasons. Comparisons were made between levels of soccer competition and playing positions (i. e.

A Reduction in Match-to-match Variability Using Maximal Mean Analyses in Sub-elite Soccer.

The match-to-match variability of external loads in National Premier League soccer competition was determined. Global positioning systems (GPS) data were collected from 20 sub-elite soccer players over 2-10 matches from a single season. Match data were collected from during one season.

The effect of isokinetic dynamometer deceleration phase on maximum ankle joint range of motion and plantar flexor mechanical properties tested at different angular velocities.

During range of motion (max-ROM) tests performed on an isokinetic dynamometer, the mechanical delay between the button press (by the participant to signal their max-ROM) and the stopping of joint rotation resulting from system inertia induces errors in both max-ROM and maximum passive joint moment. The present study aimed to quantify these errors by comparing data when max-ROM was obtained from the joint position data, as usual (max-ROM), to data where max-ROM was defined as the first point of dynamometer arm deceleration (max-ROM). Fifteen participants performed isokinetic ankle joint max-ROM tests at 5, 30 and 60° s.

Stretch imposed on active muscle elicits positive adaptations in strain risk factors and exercise-induced muscle damage.

Introduction: Stretching highly-contracted plantar flexor muscles (isokinetic eccentric contractions) results in beneficial adaptations in muscle strain risk factors; however its effects in other muscle groups, and on architectural characteristics and exercise-induced muscle damage (EIMD), are unknown.

Methods: The influence of a 6-week knee extensor training program was studied in 26 volunteers (13 control; 13 experimental). Before and after the training program, passive and maximal isometric and eccentric knee extensor moments and range of motion (ROM) were recorded on an isokinetic dynamometer with simultaneous ultrasound imaging of vastus lateralis (VL).

Stretching of Active Muscle Elicits Chronic Changes in Multiple Strain Risk Factors.

Introduction: The muscle stretch intensity imposed during "flexibility" training influences the magnitude of joint range of motion (ROM) adaptation. Thus, stretching while the muscle is voluntarily activated was hypothesized to provide a greater stimulus than passive stretching. The effect of a 6-wk program of stretch imposed on an isometrically contracting muscle (i.